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DIY iPhone 3G Charger

Today one of my readers emailed me a photo and a schematic of an iPhone 3G charger that he built himself. It is also based on a voltage divider network providing a set voltage reference for the data pins of the USB port. Although the values of the resistors are different from my own iPhone charger design, the reference voltage still triggers the iPhone to start charging.

Thanks petteri for the photo! That's an iPhone 3G charging by the way. Original image: http://www.wintoosa.com/files/iphone3g.jpg

I mentioned in my post How to Charge an iPhone that I did not exactly know why the iPhone only charges when reference voltages are applied to the data pins. I designed the charger by mimicking exactly what the original iPhone charger does, which is by supplying reference voltages to the data pins. Recently, I did a search on the charging circuit of the iPhone and found this:

The IC in the red box is the Linear Technology LTC 4066 USB Power Controller and Li-Ion Linear Charger with Low Loss Ideal Diode. Logic board of the iPhone shown.

I went and dug up the datasheet for the LTC 4066 and it describes the operation of the IC. And now the answer to why the iPhone charges with a reference voltage to the data pins is revealed.

The LTC 4066 is a device that controls the power going to the iPhone's circuits. It determines if the iPhone should use battery power or USB power. Obviously, USB power can only be available if the USB plug is connected. But USB power will only be used if 500mA is given by the USB supply (computer/charger). To get 500mA from a computer, negotiation needs to be done between the device and the computer.

For a USB charger however, 500mA is already present but we need to tell the iPhone that it is available. We do this by pulling up both HPWR and WALL pins to above 1.25v:

So we can now assume that the above two pins are connected to the data pins of the USB port although I cannot confirm that with 100% confidence. Anyhow, as long as the pins are pulled above 1.25V, the iPhone should start charging and using power from the charger.

This charger design has also been tested and found working on Sony MP3 players. Due to the relatively low currents involved, it should be relatively safe to test this circuit in any device that charges through the USB port. But just in case, I will not be responsible for what ever that you do with the information contained here. I can guarantee that it works on an iPhone and an iPhone 3G.

UPDATE: Petteri has told me that a Celly charger advertised to work on an iPhone DOES NOT work on the iPhone 3G. Below are photos from him:

Celly charger.

iPhone 3G not charging.

So when you buy a charger for your iPhone 3G (for whatever reason since a travel charger is already included), make sure it works first. Thanks Petteri for the tip.

Also, John Baxendale has written an excellent guide on how to modify a car USB charger to charge the iPhone.

Posted on Tuesday, July 15 @ 23:15:31 MYT (56483 reads) by tzywen

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With 21 years of real life experience, this is where I put them to good use. Here, I post up snippets of my life, interesting things that I do, current projects, outings and events and sometimes something very random.

Currently with MAS studying for my aircraft maintenance license, I'm passionate about my job (or technically my future job), computers, gadgets, electronics, cool stuff, cars, technology, and the environment. I love sports, traveling and enjoying nature. I unwind by sleeping.

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"DIY iPhone 3G Charger" | 171 comments | Search Discussion

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Measured on the original Apple USB plug = D- = 2.8V, D+ = 2.0V (and of oiwer (5V, gnd))
Loading with these values work.
Also working is both on 2V
What doesn't work is if D- =2.6V and D+ - 3.9V!!! so not every value above 1.2V starts loading the iPhone.
or is it so that D- > D+ ???

Posted by: Brail (http://www.apple.com) on Tuesday, July 29 @ 17:31:53 MYT

If they just need a voltage above 1.225, why not both connect them to the (same) 2.5v wire? Then you need only 2 resistors.

Posted by: Trogdor (http://www.apple.com) on Tuesday, July 29 @ 19:36:23 MYT

Brail: I'm thinking if the values are fairly close to those supplied by the apple charger, it will work. I did not dare try higher voltages. There are some range for the voltage values for the pins in the datasheet. So if we supply within the required range, we can trigger the chip to start charging.

Posted by: tzywen (http://tzywen.com) on Tuesday, July 29 @ 23:45:12 MYT

Trogdor: yes, that should work also. When I designed this charger, I did not know how the chip functioned. I just copied the voltage values of the apple usb charger, hence the dual voltage divider network. I'm sure there are simpler ways of doing it, like your suggestion of using just 2 resistors ;)

Posted by: tzywen (http://tzywen.com) on Tuesday, July 29 @ 23:48:23 MYT

Excellent. I simply used two 170k resistors and to give 2.5V at both D+ and D- and it works perfectly for my iPhone 3G. Thanks again.

Posted by: Steve (http://www.workware.net.au/) on Wednesday, July 30 @ 07:15:14 MYT

steve: Thanks for sharing that with us! Now we have a simpler way of making a charger for the iphone

Posted by: tzywen (http://tzywen.com) on Wednesday, July 30 @ 21:47:29 MYT

Steven, can you post the schematic you used with 2 resistors? I have a nano 3G and it won't charge from my wall USB adapter (those nanos didn't come with a wall charger u.u). Thanks in advance! and tzywen, nice idea!!! Congrats for this ;D

Posted by: Letsan on Thursday, July 31 @ 11:37:12 MYT

Sure, Letsan, but it's so simple it is hardly needed.

See http://members.westnet.com.au/stevebennett/iphone/iphone-usb-charger.jpg

Note that I used 170k because that's what I had lying around. 100k or so would be fine too.

Posted by: Steve (http://www.workware.net.au/) on Thursday, July 31 @ 12:35:31 MYT

Letsan: no problem. credits to Steve for finding and testing the 2 resistor method!

Posted by: tzywen (http://tzywen.com) on Thursday, July 31 @ 18:57:37 MYT

I wonder if there will be a problem shorting D+ and D- together using the two resistor method. Thoughts?

Posted by: Mark on Monday, August 04 @ 04:42:31 MYT

If it's solely for charging, it shouldn't be a problem. But if it's used in conjunction with data transfers, then you might have problems.

Posted by: tzywen (http://tzywen.com) on Monday, August 04 @ 18:05:43 MYT

I just tried the 2 resistor method with 100K resistors for a reading of 2.6V on D+ and D- and my iphone 3g charges now. Thanks guys.

Posted by: Troy on Thursday, August 07 @ 08:30:17 MYT

DIY on an iphone 3g charger? inspiretech.com sell one for 7 bucks..

Posted by: garrett (http://www.inspiretech.com/p-348-iphone-3g-travel-charger.aspx) on Friday, August 08 @ 14:17:57 MYT

@tzywen: Any ideas how to use this method, and be able to use the USB line for data transfer. Not at the same time, is in necessary to use a switch, or is it possible to have 4 resitors with higher values?

Posted by: ges (http://nourl) on Friday, August 15 @ 06:53:32 MYT

Using 4 resistors with higher values may work, but I think the switch approach should be a better option. But it requires human intervention. Will see if I can come up with a diagram soon.

Posted by: tzywen (http://tzywen.com) on Friday, August 15 @ 07:32:20 MYT

Two resistors: 150K and 100K to give 2V on both data pins works fine. Managed to build it into a few spare holes left in the PCB of an old Sony Ericsson charger I had lying around!

Posted by: Slash on Saturday, August 16 @ 01:13:00 MYT

Has anyone traced the pinouts from the LTC4066? In particular I'm wondering about pin 10 CLDIS. This is the current limiting disable pin. I ask because myself and several other people are having problems charging our 3G iPhone under heavy use (3G network, leaving GPS on, bluetooth, wifi, etc). The datasheet says the battery charge current is reduced so the current load doesn't exceed the input. What we are seeing is that our phones are discharging even while plugged in.

The battery is rated at 1150mA but USB adapters are being capped at 500mA.

I know all 4 USB pins are accounted for but I'm wondering if one of the dock pins leads to pin 10 on the LTC4066. I looked at the dock pinouts from http://pinouts.ru/Devices/ipod_pinout.shtml and a couple of pins are listed as just connecting to the motherboard....

I really hope CLDIS goes somewhere, otherwise Apple made a device that can't be used non-stop under heavy load. Having to close your running app and turn off the screen to charge the phone is really annoying. The is going to be a big issue when turn-by-turn GPS software comes out (if it does).

Posted by: Chase (http://www.osdev.org) on Thursday, August 21 @ 10:35:38 MYT

Chase: that's a very good question. unfortunately, we can't be sure if CLDIS is connected unless we open up the iphone and trace the tracks and see if they are actually connected. But I'm assuming they are not connected to either 1 of the 2 data pins because then you won't have a problem with discharging while plugged in. Modifying a dock connector will be a lot of work since it looks sealed.

If under heavy usage your phone discharges even when plugged in, that means the iphone is drawing more than 500ma and the battery will die in just 2 hours if not plugged in?

Posted by: tzywen (http://tzywen.com) on Thursday, August 21 @ 22:16:40 MYT

I've been wondering if that phenomenon was perhaps a defective handset, Chase, but since other people are seeing it I'm afraid that it's a design issue. I've had times where the phone was sitting on the dock, connected to my computer, running an application under development, and still managed to deplete the battery (!!!). Needless to say, this shouldn't be happening. Your mention of a current limiter similarly scares me with the thought that they foolishly designed the handset assuming that no one would be using it while it was charging. (Uhm, hello? Developers? Why does Apple hate iPhone developers so??) Unfortunately if this is all so, then it suggests that the CLDIS is -not- attached to the dock, since I've seen the depletion phenomenon happen while the 3G was -on- the (iPhone 3G specific) dock

Posted by: Xeri on Wednesday, August 27 @ 06:06:06 MYT

Xeri: I have a feeling that if the iPhone 3G specific dock doesn't override the current limitation, then the CLDIS isn't connected.

I can't really think of any reason not to include this pin, except for the lack of available pins on the connector or the designers might think that it wasn't required to override the current limit.

The increase in input current will not fry or explode the battery because PROG (pin 23) is used to control the battery charging current. So again, no reason not to disable the current limit when it's on the dock.

Posted by: tzywen (http://tzywen.com) on Wednesday, August 27 @ 18:26:40 MYT

Finally!

Managed to make it work with 3 resistors, cause I didn't have the right resistances (tried with 180K and about 60K, and didn't work). Using 180K in the first one and 60K+20K in the second one triggered the iPod nano 3g to charge!!

Thanks a lot, finally there's a way to charge my ipod without a computer :)

Posted by: Letsan on Tuesday, September 02 @ 13:31:17 MYT

Letsan: good job! nothing like plain old trial-and-error. Just becareful not to fry your ipod/iphone in the process ;)

Posted by: tzywen (http://tzywen.com) on Tuesday, September 02 @ 14:18:44 MYT

Hey it works !! good job guys , nice not having to shell out for another car charger...

Posted by: Richard on Saturday, September 06 @ 22:52:44 MYT

I used the 100k resistor method to charge my 3g, but it only charged a few times and now it won't charge anymore. Nothing had been updated, nothing new changed to the setup or firmware. Connections are ok, just weird.

Posted by: kung on Saturday, September 13 @ 05:47:16 MYT

Kung: have you tried the circuit by petteri in the first photo? it could be that because of the high resistance value (100k), an increased draw in current on the data pins will cause the reference voltage to drop considerably. Try using a lower resistance value. Please let me know if it works out ;)

Posted by: tzywen (http://tzywen.com) on Saturday, September 13 @ 12:44:26 MYT

Hello,

I only have 182Kohm resistors laying around. Would these work?

Posted by: lolento on Tuesday, September 16 @ 02:58:57 MYT

Hi,

I found some 100k reistors and build a circuit around that.

I have two different kinds of chargers laying around some with 500mA rated current, others with 500-1000mA current. The two resistor circuit with 100Kohm only worked with chargers running 500mA only. It would not charge on 500mA-1000mA chargers. Anyone else seeing this?

Posted by: lolento on Tuesday, September 16 @ 15:09:00 MYT

lolento: you can use similar value resistors but try not to deviate too far because it would affect the reference voltage. As to why some chargers work and some don't, I think it's down to their design. For the one I built, it worked right out of the box. Good luck with yours!

Posted by: tzywen (http://tzywen.com) on Tuesday, September 16 @ 19:34:28 MYT

Thanks Tzywen,

In general, what do you think is a good keep out zone in terms of resistance for the two resistor circuit?

Thanks.

Posted by: lolento on Wednesday, September 17 @ 01:14:06 MYT

Thanks! I've been wondering what it would take to build my own charger circuitry for a special automotive application and now you've told me exactly what I need to do.

Posted by: Fredman on Wednesday, September 17 @ 04:47:11 MYT

BTW, I used a pair of 10K resistors for the divider and that worked fine on the breadboard.

Posted by: Fredman on Wednesday, September 17 @ 04:57:32 MYT

Hey Fredman,

What is the voltage you're getting from d- and d+?

Posted by: lolento on Wednesday, September 17 @ 06:52:44 MYT

Lolento, I'm dividing the USB 5V with a pair of 10K resistors, so I'm supplying the phone D+ and D- with 2.5V. Or did I misunderstand your question?

Posted by: Fredman on Wednesday, September 17 @ 06:57:20 MYT

@lolento

I used 180K on the first one, and about 80K on the second resistance. You could try using 180K in the first one and 2x180K in parallel in the secind resistance (that would be around 90K if i'm right, but that's a lot of time since last worked with electrodynamics).

Posted by: Letsan on Wednesday, September 17 @ 14:12:35 MYT

lolento: Anything above 10k should be ok because that will limit the current flowing through the resistors to less than 0.5ma.

fredman: great that it's working good for you ;)

Letsan: yes, you're right by saying that 2x180k in parallel will give 90k

Posted by: tzywen (http://tzywen.com) on Thursday, September 18 @ 01:22:17 MYT

I wonder if there's anything standard about this. I'd like to hack my USB chargers so they work with as many devices as possible, but there's not much point in using this scheme if it only works with iPhones. Unfortunately there's no specific information readily available about how USB power negotiation works.

Posted by: DrLex (http://www.dr-lex.be/) on Sunday, September 28 @ 04:57:57 MYT

DrLex: Some devices requires just 5volts from the power pins to start charging. Some devices like the iphone needs extra voltages just to get them to start charging. I own a couple of devices that charges through usb and the iphone charger charges them just fine.

So I think it's best that you try it out with all your devices and see if you can just have one that charges them all. Or if you want, build a usb-hub type charger with many ports, each specializing for one device.

Posted by: tzywen (http://tzywen.com) on Sunday, September 28 @ 14:56:44 MYT

I bought an car-kit for my car that makes the factory-fitted hi-fi unit think my ipod is a 6-disc CD changer (basic description).

It works well with both my 2nd-gen iPod Nano and my 160Gb iPod Classic.

With my iPhone 3G, it allows the audio to play but won't charge it. I believe (from Googling) that this is because this kit uses the FireWire pins to charge iPods, which the iPhone 3G doesn't support.

A comoany called Ridax sell a small adapter, but it costs $40 and there can't really be much involved (http://home.swipnet.se/ridax/connector.htm?connipod.htm).

So I thought I'd have a go at building my own one that replaces the lead that connects the iPod to my car-kit.

The car-kit is from Connects2, and I have contacted them about a replacement lead that works, but ahven't heard anything back yet.

I'll need to do some work to figure things out, but wondered if anyone has looked into this already?

Neil

Posted by: NeilD on Monday, September 29 @ 16:37:33 MYT

NeilD: I've looked at the Ridax device and obviously there's really nothing much involved inside. it probably just supplies voltage signals to the data pins to start the iphone charging.

If the lead that you are going to modify have connections to the data pins on you iphone, then you can simply just supply those reference voltages and make it charge. good luck!

Posted by: tzywen (http://tzywen.com) on Monday, September 29 @ 22:35:15 MYT

Would it be possible to build an adapter of sorts?

I've got an emergency battery that charges devices over usb...could I not plug a usb cable into that and splice it and then put this configuration into like an altoids box or something, then providing a standard usb plug on the other end?

How would the wiring work on that?

Posted by: Stephen on Sunday, October 05 @ 12:37:32 MYT

Stephen: yes, it is possible. You can simply get a male-female usb cable, splice it and insert the resistors so it provides the proper reference voltages to the data pins. You might not even need to use an altoids box since the resistors are very small.

I've drawn up a schematic here: http://farm4.static.flickr.com/3113/2915404154_fc050b2907_o.jpg

that should help you with your adapter ;)

Posted by: tzywen (http://tzywen.com) on Sunday, October 05 @ 23:22:31 MYT

Is this totally safe to use with the iPhone?

Stephen

Posted by: Stephen on Sunday, October 05 @ 23:53:40 MYT

Also, my emergency charger supplies 700mA. Does the phone therefore draw 700 and would I need to change the resistors or does it only draw 500mA?

Posted by: Stephen on Sunday, October 05 @ 23:55:46 MYT

Stephen: It is safe with the iPhone. You don't need to change the resistor values because the voltage is the same (5v). The draw current is limited by the charging circuit inside the phone.

Posted by: tzywen (http://tzywen.com) on Monday, October 06 @ 17:31:53 MYT

What would be a good way to contain this so I don't have resistors hanging out?

Posted by: Stephen on Monday, October 06 @ 21:58:40 MYT

Stephen: the neat and proper way would be to use heat shrink tubings. but if you want, duct tape works well too ;)

Posted by: tzywen (http://tzywen.com) on Tuesday, October 07 @ 00:10:26 MYT

I wonder if any of this is fixable via software? Some sort of hack to control the IC. Once the "switch" is flipped, it will start charging....the reference voltages don't need to be constant. What do you think?

Posted by: John (http://www.tzywen.com) on Friday, November 07 @ 11:11:27 MYT

John: I don't think so because the IC is hardwired and not programmable. but it's not too hard to get the reference voltages so i think that will be an easier way to do it than modify the software :)

Posted by: tzywen (http://tzywen.com) on Saturday, November 08 @ 00:50:37 MYT

Yeah, I think my solution would be at the firmware level, it would be interesting to see if something like that would be doable. It would make it convenient such that we would not have to build a module in between charger and iphone. So far I've found 2 guys who are selling a solution if you care to share - CableJive and Ridax. From a design standpoint, it's simpler to use 2 resistors, but is that method more stable? I've been reading on posts around here that the 2 resistor method seems to be possibly unreliable, however that may be due to the resistance used by the implementor. So what resistors would I use for something stable and reliable? TIA for the input.

Posted by: John on Saturday, November 08 @ 09:04:43 MYT

John: some comments have found that the 2 resistor method works. they seem to be using the 10k resistor. I don't have an iPhone 3G so I cannot verify that. but since they're resistors they should be stable for everyday use.

Posted by: tzywen (http://tzywen.com) on Sunday, November 09 @ 23:08:22 MYT

I used 2 1M resistors, spliced a male to female usb cable, put the resistors in between and all is good. I think I need to check my soldering, because it sometimes will not charge. Thx for the help

Posted by: John on Monday, November 10 @ 06:27:44 MYT

John: 1M resistors might be too large. because of the large resistance, the voltage drop across them will increase as current increases. Try using a smaller resistance and you might solve the intermittent charging problem

Posted by: tzywen (http://tzywen.com) on Monday, November 10 @ 21:51:45 MYT

I have an Ipod bluetooth dongle that is also able to charge the IPOD through USB. I tried this on the IPhone and the IPhone 3G, while it works on both and seems to charge both when first connected it comes up with a message saying: This is not an approved accessory, would you like to put the phone in aeroplane mode. Hit no and the dongle works fine.
The reference voltages on both USB data pins is around 2v, has anyone else had this come up or know why it comes up eventhough it seems to work ok.

Posted by: Tony on Tuesday, November 11 @ 13:52:30 MYT

Tony: I think one of the pins are used to identify the accessory being connected to the iphone. If the iphone senses an accessory that doesn't suit it, it will display that message. maybe somehow the accessory is working and suits the iphone, but the identity of the accessory shows otherwise or is unconfirmed.

Posted by: tzywen (http://tzywen.com) on Thursday, November 13 @ 05:10:49 MYT

Could be pin 21, which the Ipods use to identify which accessory has been connected?? Wonder what the the resistance is on this pin using genuine iPhone accessory interesting to see if it differs from the diferent resistances the iPod is expecting to see when an accessory is connected.

Posted by: Tony on Thursday, November 13 @ 08:01:21 MYT

Tony: yes, I think that's the pin that you should be looking at.

Posted by: tzywen (http://tzywen.com) on Thursday, November 13 @ 20:58:09 MYT

New info, you dont need to send voltage to both pins it is not advaisable.

this is part of the USB standard. A USB device must indicate its speed by pulling either the D+ or D- line high to 3.3 volts. These pull up resistors at the device end will also be used by the host or hub to detect the presence of a device connected to its port. Without a pull up resistor, USB assumes there is nothing connected to the bus.

High speed means also high current so you only have to do a voltage divider with 2 resistors to get 3.3 volts and then connect it to one of the data pins, this works already did it.

cheers.

Posted by: loobates on Monday, November 17 @ 03:46:17 MYT

loobates: Can you explain why it's not advisable to send voltage to both pins? Because that's exactly what the original iPhone charger is doing.

Anyways, thanks for showing us your 3.3v method. I'm always looking for new ways to charge an iphone because I believe there's more than one way of doing it ;)

Posted by: tzywen (http://tzywen.com) on Monday, November 17 @ 23:52:34 MYT

Thanks for the info all, but I have a problem.
First of all, I have a 16GB iTouch 1G and not an iPhone.
I am modifying generic AC-USB adapters.

I've tried a few ways and haven't gotten a successful charger yet.

With 2.5V to D+ & D- and it just recognizes it at as AC adepter but won't charge.(100K-100K)
With 2.5V and 2V it will start to charge and then got to AC. (10K-10K/10K-15K)
And with 3.4V to D- and nothing to D+ , start to charge then go to AC. (22K-10K)

Any suggestions on where I've gone wrong?

Posted by: Daunte on Saturday, November 22 @ 00:03:23 MYT

Daunte: can you make sure that you have a stable 5v supply? 10k resistor should be ok. But I have not tried it on an ipod touch so i don't know if it works or not. But I'm guessing it should because in this picture of the disassembled ipod touch (http://images.appleinsider.com/ipod-touch-teardown-11.jpg), there's the LTC4066 chip.

Posted by: tzywen (http://tzywen.com) on Sunday, November 23 @ 01:35:56 MYT

I'm trying to achieve the opposite : I'd like to build a USB cable that connects my iPhone to my computer, but doesn't charge the battery. Battery life is shortened by recharging a non-empty battery too often, so I want a way to sync my iPhone, but not charge it.

I tried making a usb cable with the +5V wire (pin 1) cut, but no response anymore, neither loading, nor connecting.

Any experiences with this?

Best regards,
Marvelade

Posted by: marvelade (http://www.marvelade.com) on Monday, December 08 @ 21:10:26 MYT

marvelade: That's a very interesting concept that you're trying out. Yes, it is true that constantly recharging a battery is not good. but battery technology have advanced pretty far since the days of NiCD and NiMH with "memory" issues. the lithum battery in the iPhone should be able to go through many recharging cycles without problem. and also, the charging is controlled carefully by a chip so the battery shouldn't suffer from any overcharging which will shorten its life.

I don't know if you can just sync your iPhone without charging it. If you do find a way to do it, let us know.

Posted by: tzywen (http://tzywen.com) on Monday, December 08 @ 23:52:20 MYT

I've figured out that the communications circuit inside the iPhone needs to be powered (like all circuits ;) ) to function. This power comes from the +5V pin of the USB cable, so there is no such thing as being able to communicate without the 5V voltage attached. One thing requires the other.

Best regards,
Marvelade

Posted by: Marvelade (http://www.marvelade.com) on Monday, December 15 @ 02:48:34 MYT

The resistor method works when my iPhone is almost fully charged.
I the battery on iPhone is less than 3/4 the iPhone does not recognize the hacked charger. Very odd!

Posted by: Mgsusa (http://nosite.com) on Monday, December 15 @ 04:39:12 MYT

Marvelade: thanks for the feedback. I guess you shouldn't worry too much about charging the battery too many times. It should last you for years

Posted by: tzywen (http://tzywen.com) on Monday, December 15 @ 18:07:32 MYT

Mgsusa: Hi, may I know what value resistors are you using? iPhone 1st gen or 3G? And is your 5v supply properly regulated?

Posted by: tzywen (http://tzywen.com) on Monday, December 15 @ 18:09:13 MYT

how about putting some diodes in there to prevent the iphone charging your 4xaas once they max out thier charge?

Posted by: laz on Saturday, December 20 @ 12:31:12 MYT

laz: I don't think diodes will be necessary because the iPhone can't provide power from its USB port

Posted by: tzywen (http://tzywen.com) on Saturday, December 20 @ 19:39:52 MYT

good point!

i'm using 4 AA rechargable batteries and i cant get this to work.

i'm trying to figure out what kind of drop down resistor i can use to get 5v from the 5.8v output of the battery pack. but i don't know how much the iphone current draw is. im currently looking at the data sheet and it's not clear to me what this is.

any help here?

i also looked into a voltage regulator like the 7805 but that needs 8 volts to function. if that's the case i might need to add more rechargeable batteries to the mix.

Posted by: laz on Monday, December 22 @ 11:06:17 MYT

hello its been a long time,,just want to greet you a blessed christmass

Posted by: gerlyn (http://gerlyncamillo) on Monday, December 22 @ 19:45:33 MYT

laz: 4AA rechargable batteries will give you about 4.8volts. I would say it's safe to just charge the iphone directly with the batteries. But as a precaution, I would suggest you either add more batteries and get a 5v voltage regulator or use a DC to DC converter to step up a lower voltage to 5volts. I think we can safely assume that the iphone will not draw more than 500ma.

Posted by: tzywen (http://tzywen.com) on Tuesday, December 23 @ 01:06:39 MYT

gerlyn: hey have a merry Christmas too!

Posted by: tzywen (http://tzywen.com) on Tuesday, December 23 @ 01:08:56 MYT

ok

so i now have 6xaa rechargeable batteries connect and 2x4.8v batteries connected to an 7805. the AA batteries are 2x2300mAh and 4x2700mAh. The 4.8v volts batts are 600mah.

i now have a 7805 wired up.

when i measure voltage on the usb pins i get 5 and 1.9v.

the iphone says it's connected and charging but it doesn't actually charge.

i tested the circuit by connecting ONLY the +5 and gnd of a usb cable to the circuit (after the 7805) and it does charge.

i still can;t figure out why its not working.

i'm wondering if:

a) the 600mah batteries are somehow diminishing the output of the other batts

or

b) the 7805 can't put out enough current (mA)

here's a link to the data sheet:

http://www.alldatasheet.com/datasheet-pdf/pdf/22676/STMICROELECTRONICS/7805CV.html

i don't have any capacitors int he circuit. culd this affect it in any way?

if i need caps how do i wire them up? ive seen a bunch of different circuit diagrams that have a bunch of different values.

Posted by: laz on Tuesday, December 23 @ 12:33:37 MYT

I have made 2 DC-DC converter USB chargers according to the 100K---20K---100K arragement to feed voltage signals to the D+ and D- line. The result is mixed and I think your guys may be interested to know. 1 converter may have higher capacity(>500ma?), it works just fine, the iphone can be charged. The other one has a current capacity of 300ma output would switch on an off and I guess the overcurrent protection was activated. The alarming effect of this is that after a few cycles of ON and OFF, the iphone was frozen and lost control and even turned on playing music automatically. I was panic and turned off the iphone power. restart the iphone seems to be OK. After the instance I thought as the data line has been connected, if you feed some garbage signal to it, it may trigger some unpredictable reaction so the alternative charger should have enough capacity(>1.2 A?) and have relatively clean DC voltages.

Posted by: Tim on Tuesday, December 23 @ 21:35:18 MYT

laz: it's better if you don't mix different types of batteries. capacitors are generally not required for battery operation. make sure you have enough supply current to the 7805. It might not be charging because of a lack of current.

Posted by: tzywen (http://tzywen.com) on Monday, January 05 @ 22:50:56 MYT

Tim: thanks for sharing with us your findings. The data pins are used to communicate with the iPhone so I think sending it noisy DC voltages may have somehow triggered the phone to do unexpected things. A filtering cap should do the job

Posted by: tzywen (http://tzywen.com) on Monday, January 05 @ 22:59:30 MYT

I'm using the two resistor method (both 20K). I have 4 x rechargeable AA as my power supply. There is no voltage regulator. I found that it works, except when I use fully charged batteries. I have a iPod Touch 2G.

Using an adjustable power supply, I found that the voltage must be less than 5.55V for the charger to be recognized. Doing the math, this means 1.375V/battery. My fully charged batteries are around 1.4V each - which explains my result. Using the power supply, the Touch showed "charging" all the way down to 4.4V.

Measuring somewhat drained batteries with no load showed 5.05V. After connecting them to the Touch (which showed "charging"), the voltage dropped to 4.80V. I wonder if I could use a resistor to temporarily reduce the voltage of fully charged batteries below 5.55V, and then disconnect the resistor once charging had started and rely on the current draw by the Touch to keep the voltage at an acceptable level?

This is all very useful information. Thanks to everyone who contributed!

Posted by: EngineerType (http://tzywen.com) on Tuesday, January 06 @ 04:03:17 MYT

5V voltage regulators typically require an input voltage of 7V or more, so they won't work with just 4 AA batteries. What is the best way to reduce the voltage of 4 AA batteries to 5.55V so that charging can start? Thanks!

Posted by: EngineerType (http://tzywen.com) on Tuesday, January 06 @ 08:56:46 MYT

An observation: I only needed to apply 2.5V to one of D+ or D- for charging to start. I'm not sure which one though. In the end I connected both to 2.5V.

Posted by: EngineerType (http://tzywen.com) on Tuesday, January 06 @ 09:01:56 MYT

EngineerType: Thanks for sharing that finding of yours. So it seems that overvoltage will cause the ipods to stop charging.

I've always used a regulator because it's a safer way. You can use LDOs, or DC-DC converters. But an easier way will be to add more batteries and regulate them down with a linear regulator like the 7805.

Not sure if connecting only one of the data pin works since the original charger has voltages to both pins. But you can probably figure it out through trial and error ;)

Posted by: tzywen (http://tzywen.com) on Tuesday, January 06 @ 21:24:01 MYT

If you need a charger, get it at iGearUSA.com for only $8.99

Posted by: iGearUSA.com (http://www.iGearUSA.com) on Thursday, January 08 @ 07:00:31 MYT

I've been simulating the 3 resistor divider for the last week and these are my latest values.

5V-----220K---(2.5V)----68K----(1.7V)-----150K---0V

The current in the circuit above is 11.42uA. 2.5V to be supplied to D- and 1.7V to be supplied to D+.

Tzywen, you mentioned that the iphone only draws 10uA, but your circuit supplies 20uA, would the 10uA be too little?

Is the LTC4066 only looking at the voltage or does the current have an effect also?

Is there a voltage drop when you connect the charger to the phone?

Does the phone's internal charging circuit tell it when to stop charging when using the hacked charger?

How would this charger affect the iPhone 3G's ability to both charge and independantly supply power for opperation as claimed?

On both your charging pics the iphone indicates a plug within the battery, which indicates it is fully charged, should it not be displaying a lighting bolt in the battery?

I am yet to test the circuit above.

Posted by: 99GAZI (http://www.facebook.com) on Friday, January 09 @ 16:55:40 MYT

99GAZI:

The current draw actually depends on the iPhone. The resistor value won't affect how much current is consumed by the iPhone (provided the reference voltages are the same when comparing different resistor combinations) because the resistors are just there to provide the proper voltages for charging. If the reference voltages changes, then yes, the current draw might change also.

The LTC4066 is looking at the voltages. A small current will flow so the voltage can be "measured".

If your resistor values are not too big, then the voltage drop may not be significant. Remember that when current draw increases, voltage across a resistor will drop. You can try using small value resistors if you find that the voltage drops too much when plugged in.

Yes, the iPhone's internal circuitry will tell it when to stop charging. We're fooling it into thinking that it's plugged into the orignal wall charger supplied by Apple.

Again, this charger will not affect anything because it functions exactly like the original charger.

On one of the photos (http://farm4.static.flickr.com/3279/2505609126_e52bf6af44_o.jpg), I think it's showing the plug because it's fully charged. And on this I think it's a lightning bolt (http://farm4.static.flickr.com/3104/2619837795_42e1812426_o.jpg). I don't have the original photos anymore so I can't zoom in and double check.

Do let me know after you've tested it. Looking forward to seeing your results.

Posted by: tzywen (http://tzywen.com) on Friday, January 09 @ 19:04:29 MYT

Tzywen

Thanks for your help :-)

The charger works perfectly.

I was praying really hard when I plugged it in the first time, but its over now.

Now just to test it in the car.

Posted by: 99GAZI (http://www.process-auto.com) on Friday, January 09 @ 21:39:48 MYT

Hello everybody, probably this is not the place to ask for help, but as I can read on your amazing adventures around the IPHONE charging, maybe someone can help me: I used an old Iphone car charger with the 3G Phone - It seems to be fried, now the only thing I get it's the screen with the battery very low and doesn't charge anymore and it's hot, I almost can frie an egg on it!

Posted by: Windss (http://www.rtp.pt) on Saturday, January 17 @ 21:44:15 MYT

Windss: the old iPhone charger shouldn't fry your 3G iphone because both chargers are very similiar in operation. But from how your described it, it seems like one of the chips got fried. I think the only option now is to send it back to Apple for warranty.

Posted by: tzywen (http://tzywen.com) on Sunday, January 18 @ 21:56:25 MYT

Thanks Tzywen, I checked the charger, it seems to be an old IPOD charger I wasn't wearing glasses when I bought it in a gas station (12v). It's strange how apple used the same socket with different voltages, other brands are always keep changing

Posted by: Windss on Monday, January 19 @ 00:52:43 MYT

Windss: unless im mistaken, older ipods charge through firewire using 12v. and the pins for firewire power are different so it could not have fried your iphone. pinouts are here: http://pinouts.ru/PortableDevices/ipod_pinout.shtml

so it might not have been the charger. anyways, i think bringing it back to apple is the only option now. Good luck!

Posted by: tzywen (http://tzywen.com) on Tuesday, January 20 @ 00:14:32 MYT

I have an iPod Touch and since those data pins just have to be over 1.225 V I just tied them both to the 5V (no resistors needed). It appears the ipod is charging but I'll let you know in the morning (it is hard to see the bar move but it has the charging icon in the upper right-hand corner).

-Elliot

Posted by: Elliot on Wednesday, January 28 @ 15:13:56 MYT

Elliot: I would recommend you use current limiting resistors so you won't inadvertantly fry your ipod touch. I have not tried it with 5v so I'll be looking forward to your findings.

Posted by: tzywen (http://tzywen.com) on Friday, January 30 @ 00:22:39 MYT

You guys are all using resistors in the kilo ohm range. I have 220 and 100 ohm resistors lying around. tzywen said the chip regulates the current so will using those resistors be ok?

I'm using a old apple firewire adapter with a 5v regulator. The output current on the adapter is 0.67A and the max output on the regulator is 1.0A.

Posted by: mab on Saturday, February 07 @ 18:52:44 MYT

mab: the resistors are to form a voltage divider network, not to reduce the current to the iphone. It is ok to use resistors with values of 100ohm and 220ohm provided they are rated at 1/2w.

This however is inefficient because more energy (heat) will be lost through the resistors. By using higher values (in the kiloohm range) you reduce the energy that is dissipated by the resistors. and you can get away with using 1/4w or 1/8w resistors.

The firewire adapter should be ok just as long as you regulate it down to 5v.

Posted by: tzywen (http://tzywen.com) on Sunday, February 08 @ 00:57:11 MYT

tzywen,
have you heard/tried 4 AA NiHM batteries directly to USB 5v and Gnd?
I'm planning to use 4 AA NIHM batteries for the USB 5v and Gnd (directly no voltage regulator/resistors) on an iphone 3g. NiMH nomial voltage is around 1.2v a cell, however, fully charged, voltage can go as high as 1.4v. This means the voltage is actually around 5.6v or (possibly) 5.8v.
(but wikipedia says "1.35–1.4 V (unloaded)" and "1.2 V/cell during discharge")
I read the datasheet for the LTC 4066, but it says max voltage on IN pin is 5.5v

I am curious- have you tried/know of anyone who tried using 4AA batteries, fully charged, directly (no voltage regulator or resistor) with an iphone?
I'm hoping to find someone with exdperience with this before I risk bricking it >.<

Thanks in advance,
CKC

Posted by: CKC on Friday, February 20 @ 07:32:35 MYT

Hello All,

if you want to create 2V for the (D-) and 3V for the D+ from the single source,
why not use just 3 standard resistors in series and get te voltages, like
5v----------39k------(D+)--------18k------(D-)--------39k---------0V

Do you think this works as well?

greetings
felix29

Posted by: felix29 on Friday, February 20 @ 20:15:04 MYT

CKC: I would not recommend the 4AA method. One being the supply is not regulated, and secondly, if the voltage drops below a certain threshold, charging will stop. If you want to use the 4AA method, I suggest you get a boost converter to get clean and stable 5v output.

Don't think you can brick your phone if you don't apply too high of a voltage (below 5.5v). But do be careful and double check before you connect anything to your iphone.

Posted by: tzywen (http://tzywen.com) on Friday, February 20 @ 23:08:38 MYT

felix29: yes, that combination will certainly give you 2v on (D-) and 3v on (D+) respectively. it should work

Posted by: tzywen (http://tzywen.com) on Friday, February 20 @ 23:11:23 MYT

thanks and I have built and tested, it charges everything.

A more simpler version, just use 4 equal valued resistors bigger than about 68k and 2 of them in parallel and it should work very easily and you get the right voltages and only need one type of resistors like below:
5v---100k---(D+)----50k(2x100k in parallel)----(D-)---100k-----0V

greetings to all and thanks

felix29

Posted by: felix29 on Thursday, February 26 @ 23:35:01 MYT

Is it not possible to reflash this IC chip to ignore the D- D+ requirement? Any ideas?

Posted by: Diezzler on Saturday, February 28 @ 03:35:25 MYT

Diezzler: I highly doubt that. That IC is non flashable, and doing that would be too much of a hassle.

Posted by: tzywen (http://tzywen.com) on Saturday, February 28 @ 22:46:22 MYT

is this charger compatible with the kinda new ipod calassic 5.5G?

Thx guys

Posted by: jordan on Monday, March 16 @ 07:52:07 MYT

jordan: It should charge through the USB port although I have not tried it yet. Anyone can confirm this?

Posted by: tzywen (http://tzywen.com) on Monday, March 16 @ 19:01:17 MYT

could be useful: http://pinouts.ru/Devices/ipod_pinout.shtml

Posted by: Po on Saturday, March 21 @ 20:55:02 MYT

Can something like this be used to make an iPhone charge in a docking station designed for an iPod?
Obviously this uses connector on the other side of the usb cable.

agc

Posted by: agc (http://swift.cantos.us:8080/acantos/) on Sunday, March 22 @ 22:06:09 MYT

agc: yes, it charges when plugged into the original docking station that comes with the iphone. for the 3g i'm not sure but I assume it will charge as well

Posted by: tzywen (http://tzywen.com) on Wednesday, March 25 @ 22:24:12 MYT

i tryed making an adapter that goes from an old 5v 2a dc charger from my old mp3 player for my iPod touch 2g.

i found this diagram. http://picasaweb.google.com/bodo2all/PC_Stuff#5257531525468619650

i dident have any 560k smd resistors so i used some 100k ones as i had read this site earlyer but could not find it at the time.

my set up looked a bit like this

       d+      d-
          I         I
        [100k] [100k]
        [100k] [100k]
            I         I
5v--[100k]------[100k]--0v

i dont know if that makes sence but its the same as the linked diagram just 100k to make the devider and 2 100k in series to the data pins.

it wouldent chage my touch 2g it said it was running from the power adapter (little plug symbol not lightning).

i will modify it tomorrow to what "felix29" posted

Posted by: Anonymous on Thursday, April 02 @ 02:33:43 MYT

sorry about the above post i wrote it late at night and forgot to check the spelling before i posted it this morning.

anyway i changed my circuit to what "felix29" posted using 2x100k in parallel between the d- and d+ pins and it works. i tested the current draw and its exactly 500mA as expected.

im using a 5v 2000mA wall adapter and just scavenged a usb socket and dc socket. here's some pics of it

http://farm4.static.flickr.com/3438/3405690282_1f55bb60a6_b.jpg
http://farm4.static.flickr.com/3572/3405690558_c61c6ca13f_b.jpg

its not very tidy i moved the resistors around and fixed the cut tracks quickly before i started work.

i wanted a small enclosure to put it in but couldn't find anything in the short look i had so just used heat shrink

Posted by: merve0o0 on Thursday, April 02 @ 09:13:38 MYT

merve0o0: great surface mount setup you have there. Glad it worked out for you!

Posted by: tzywen (http://tzywen.com) on Thursday, April 02 @ 14:01:43 MYT

Great site and great information. It is always nice to see people working together towards a single goal and the different ways/ideas people come up with.
There is a kit out there called the mintyboost that uses 2aa's, step up converter, a few capacitors, a diode, resistors for the data pins, and an inducer to clean the signal. It works great, but is hit or miss for the iphone 3g. I built one using 4aa's (just doubled em up so output is still 3v from the batteries to the circuit) and it works great with my bb curve and bluetooth headset, but I have yet to try it with my sisters ipod touch or my fiances 3g iphone. I will report back when I test them out.

Posted by: Jason on Wednesday, April 08 @ 01:09:07 MYT

The USB spec accounts for a battery charging specification (See the "Power" section on http://en.wikipedia.org/wiki/USB) where D+ and D- are shorted together. Do these Apple devices follow that spec and if D+ and D- are shorted will the device start charging?

Posted by: opi (http://en.wikipedia.org/wiki/USB) on Wednesday, April 22 @ 10:10:22 MYT

opi: no, the iphone doesn't follow that battery charging spec. You need to give the D+ and D- reference voltages before the phone will start charging

Posted by: tzywen (http://tzywen.com) on Wednesday, April 22 @ 17:37:28 MYT

I'm trying to take the reverse engineering success you've had and now apply the USB spec information to it to see what I can learn.
In this diagram: http://www.beyondlogic.org/usbnutshell/fspullup.gif shown on this site: http://www.beyondlogic.org/usbnutshell/usb2.htm It shows a layout similar to what you posted initially yet the resistance is less. However, is this basically what your circuit is doing, signally that the "charger" is a Full Speed USB device? Thanks for your explanation.

Posted by: opi (http://www.beyondlogic.org/usbnutshell/fspullup.gif) on Thursday, April 23 @ 02:07:46 MYT

opi: No, this is not what my circuit is doing. What my charger circuit does is it signals to the LTC 4066 USB Power Controller to start charging the battery using the USB power.

The pull up resistor on the USB spec is probably to indicate the speed of the device only:

Full Speed Device with pull up resistor connected to D+

Low Speed Device with pull up resistor connected to D-

So you indicate full speed when you connect the pull up resistor on D+ and low speed when you connect the pull up resistor to D-.

Posted by: tzywen (http://tzywen.com) on Thursday, April 23 @ 17:06:15 MYT

I have sucsessfuly made a charger out of 6 AA rechargable batteries (each battery 1.2v) that works on the ipod touch 1G (maybe others).

1.)hook up the + and - of a usb female connector to the + and - of the battery pack
2.)cross D- and D+ wires (green and white) on the female connector
3.)plug in a sync cable
4.)plug in your ipod (Iphone?)
5.)CHARGING

what i want to know is if this will work with normal non-rechargeable batteries.

PS the batteries were fully charged and had a total of 8000 mah, 7.2 volts

Posted by: jordan on Saturday, April 25 @ 21:52:59 MYT

Hello i made the 2 resistor for an ipod touch 1g or 2g (not quite sure). i made it with 150k resistor, im using a power supply (it has an output of 5.2v). So it worked perfectly for a while but suddenly disconnected.

I then tried the method of 3 resistor in series.

(5V) -- 150k (3.2v) -- 150k (1.6v) -- 150k -- Ground (0 V)

Still doesn´t work.

I appreciate any help

Posted by: Gorrion on Monday, May 04 @ 11:07:26 MYT

Maybe its too late but i found what happened to mine. Maybe will help kung.

the thing is that when i made the connection i made an adaptation of a male usb, and it has to make ground with the plate of the usb ipod connection.

i hope im clear. returned to the 2 resistor connection with 150k.

cheers.

Posted by: Gorrion on Tuesday, May 05 @ 05:19:35 MYT

Why not use a small 3.3v regulator instead of resistors? Will be a lot more reliable and costs about 50c.

Posted by: Justin on Thursday, June 11 @ 00:04:30 MYT

Justin: because I had resistors lying around and resistors cost less than regulators. The original iPhone charger uses resistors also.

Posted by: tzywen (http://tzywen.com) on Thursday, June 11 @ 20:21:33 MYT

Did it this way:
Got an old usb car charger,, and when i opened it... discovered that only the Red and black pins were soldered to the board. those are 5 volts and gnd pins..center pins correspondind to the Data pins were not soldered. So what i did was getting two 100 KOhms Resistors and soldering them,.... so that first (5v) pin connected to the second pin (data) by the resistor... and did the same to the fourth ping (gnd) to the third (data).. and finally soldered tboth data pins together so it would me something like this. .

http://i1018.photobucket.com/albums/af301/Leinho/IMG_0005.jpg
http://i1018.photobucket.com/albums/af301/Leinho/IMG_0006.jpg

Sorry for the quality.. it was taken ffrom an iPhone 3G itself. (Crappy 2Mp camera :/ )..

So its an interesting procedure to make your conventionalk usb car charger into an iphone3g compatible usb car charger.. Hope it was useful :)
Thanks for the info here.. it was very useful for me..
Best wishes.. Leonardo from ARgentina :)

Posted by: Leinho from ARGENTINA on Friday, July 03 @ 05:15:37 MYT

Leinho: thanks for sharing your setup! I'm glad it worked out for you ;)

Posted by: tzywen (http://tzywen.com) on Friday, July 03 @ 15:04:55 MYT

Using some info from this page and some basic electronics knowledge, i made an adapter which will take a 7-40v unregulated input and convert it to 5v 500ma then using some of the resistor values posted in comments ended up with a charger.

pic below, crap quality as its from iphone.

http://i28.tinypic.com/11vhdm1.jpg

can post up a part list if someone wants to make something similar.

Posted by: Bad_Ad84 on Friday, July 10 @ 08:41:44 MYT

Bad_Ad84: thanks for sharing your setup. It would be great if you can post up the schematics for it ;)

Posted by: tzywen (http://tzywen.com) on Friday, July 10 @ 17:22:05 MYT

im about to put a rectifier into the setup, so the polarity of the input doesnt matter, therefore pretty much any PSU will work.

will post schematic once done.

Posted by: Bad_Ad84 on Friday, July 10 @ 19:47:39 MYT

right, this is schematic to get 5v ouput from unregulated 7-40v source, you just need to hook up usb port with resistors detailed in the comments or article here.

http://i28.tinypic.com/345zzwo.png

Posted by: Anonymous on Friday, July 10 @ 20:12:19 MYT

Forgot to put my name on post above.

here is the full part list.

1x Step down switching reg 0.5A,LM2574N-5
1x YXF Al electro cap,22uF 100V 105deg C
1x SMG Aluminium Radial Cap,25V,220uF
1x Schottky barrier diode,11DQ06 1.1A 60V
1x ELC coil inductor,330uH 0.5A
1x USB type A r/a thru-hole socket
1x DF02M-E3 Bridge Rectifier

Posted by: Bad_Ad84 on Friday, July 10 @ 20:13:21 MYT

Bad_Ad84: thanks for the info!

Posted by: tzywen (http://tzywen.com) on Saturday, July 11 @ 17:51:25 MYT

Thanks to everyone for commenting on this article, it inspired me to have a go myself and I had some success! I used two 100k resistors and soldered them straight into the USB car cigarette lighter socket charger that I had, it was a nice clean build and works a treat!

I did a full write-up of the process here with nice clear pictures, hopefully it will be of use to someone else: http://wiki.siftah.com/IPhone_3G_3GS_USB_Cigarette_Lighter_Socket_Charger

Posted by: John Baxendale (http://wiki.siftah.com/IPhone_3G_3GS_USB_Cigarette_Lighter_Socket_Charger) on Monday, July 20 @ 07:40:25 MYT

John: thanks for the excellent write up! I'm sure diyers will find it very useful so I've updated my post with a link to your guide ;)

Posted by: tzywen (http://tzywen.com) on Monday, July 20 @ 19:16:54 MYT

Ok this is what I did. I builded this circuit http://www.flickr.com/photos/41602058@N04/3834007620/ and tested it with a wall wart, rated 2100mA and giving a supply voltage of 8,22V (Measured it). The voltage between the two 100K resistors is, when the Iphone 3G is connected: 2,83V. And when the Iphone 3G is connected the circuit draws 500mA, but even with a (small) heatsink on the 7805 it still get's fairly hot. Anyway it works :) It's charging my Iphone 3G

Posted by: Guillaume (http://www.flickr.com/photos/41602058@N04/3834007620/) on Tuesday, August 18 @ 23:32:07 MYT

Guillaume: thanks for sharing with us the circuit diagram! yes, the 7805 is a linear voltage regulator so it does get hot. But rest assured that with the overheat protection built into it, you will not have to worry about frying it. Glad it worked out for you :)

Posted by: tzywen (http://tzywen.com) on Wednesday, August 19 @ 16:25:48 MYT

Posted by: windows (http://www.softxi.com) on Monday, September 07 @ 20:51:56 MYT

Posted by: games (http://www.aleab.com) on Monday, September 07 @ 20:52:33 MYT

Posted by: soft (http://soft.ixeer.com) on Monday, September 07 @ 20:53:20 MYT

I have trouble charging my 3GS software 3.0.1, it still says "This accessory is not made to work with iphone"

My readings are approx 2.3V at pin 2+3, and 4,98V at pin 1+4

Strange :/

Posted by: K on Wednesday, September 16 @ 23:23:24 MYT

K: unfortunately I don't have a 3gs to try this out. Can someone give feedback on this issue? thanks

Posted by: tzywen (http://tzywen.com) on Friday, September 18 @ 01:28:06 MYT

Excellent site!

I have a 3GS and was disappointed that an old USB car charger wouldn't charge my iPhone.. The lightening bolt shows up, but the battery still drains.

Anyway, I'm going to try the two 100k resistor hack tomorrow and I'll report back.

Posted by: Paul on Friday, September 25 @ 00:33:42 MYT

Well, my plan was foiled. I opened my USB car charger up and 2 100k resistors were already connected to pins 2 and 3. This would explain why I got the "lightening bolt" charging symbol.. My charger must not be supplying enough current to charge the phone though, since the battery percentage indicator still counts down - even while connected to power. :(

Posted by: Paul on Friday, September 25 @ 19:05:38 MYT

Paul: thanks for the feedback. Yes, there have been issues whereby unstable 5v supplies have caused iphones not to charge correctly. Due to the high current draw from the iPhone, the 5v regulated supply may not be able keep up and the voltage drops below 5v.

Posted by: tzywen (http://tzywen.com) on Saturday, September 26 @ 12:40:27 MYT

Found this page after I made this. Same problem same solution. Check out my link http://users.on.net/~nousername/iphonecharger/

Posted by: Adam B (http://users.on.net/~nousername/iphonecharger/) on Thursday, October 29 @ 19:12:46 MYT

Hello,

Can you please confirm this adaptor will charge an iPhone 3G? http://www.dealextreme.com/details.dx/sku.12210

I don't think it will because someone posted a review claiming:

Pros: * Decent size

* Wide input range
* Switchmode regulator, not linear
* Reasonably low noise on output
* Fused (2A) in case something goes wrong
* Works down to 6-7 volts, has about 0.9 volts dropout.

Cons: * Bit out of specs; 5.1 v @ no load, 5.7(!)v @ 350mA load, 5.3v @ 600 mA load
* Somewhat low efficiency, 72% @ 350mA, 79% @ 600 mA. I don't recommend running it at full load (800 mA; this will likely get very unhappy at 2x800mA) for prolonged periods.
* Somewhat shoddy build quality

Other Thoughts: It should be noted that it drags both D+ and D- (the data pins) to ~2.6 volts. This seems intentional; I can't quite see why but I imagine some devices are finicky about what they're connected to."

What do you guys think? I really need a cigarette lighter with two usb ports so i can charge my iPhone 3G + a GPS bluetooth module. Kensington have one but it is too expensive...

Posted by: Pedro Diogo (http://www.neobux.com/?rh=65586E6954686552) on Thursday, December 10 @ 22:11:04 MYT

I'm sorry, but i just read Troy's comment

"I just tried the 2 resistor method with 100K resistors for a reading of 2.6V on D+ and D- and my iphone 3g charges now. Thanks guys.

So now i know the adapter i just mentioned above will charge my iPhone 3G. :)

Posted by: Pedro Diogo on Thursday, December 10 @ 22:14:53 MYT

Pedro Diogo: all 3rd party iPhone car chargers are made differently. I myself have purchased one and it DID NOT charge my iPhone even though it was advertised as an iPhone charger. Upon opening the charger, I discovered that the 5v regulator that they used was too weak (100ma max) so I replaced it with a large 1.5a one and it charged perfectly after that.

Posted by: tzywen (http://tzywen.com) on Friday, December 11 @ 01:29:59 MYT

tzywen, thank you for your reply.

I do am aware of that. However, the user i mentioned above tested the product and said there was a voltage of 2.6 on both D+ and D- pins, so i'm guessing it will charge the iPhone correctly.

I did research (and thus found your site) because i'm aware that the iPhone needs a specific voltage to power up that IC so the battery could be charged, but i'm not saying that that adapter will charge my iPhone just because it was advertised by the seller but, in fact, because someone already tested it and pointed out the 2.6v voltage on those pins. :)

Take care.

Posted by: Pedro Diogo on Friday, December 11 @ 06:16:11 MYT

Hello

I have iphone 3gs 16gb .i bought him fm transmitter to the radio that pluge in to the iphone power connector and broadcast of music to the car radio .there is possibility to connect to this fm transmitter a cable from the 12v plug from the car so that will be able to chargethe iphone in the time of hearing music.last day i connected the cable to charge the iphone and suddenly the iphone turns off ......i believes that apparently he received high voltege from the car... how i can solve this problem?
the iphone have a electric circuit that protect from high voltege?

(I have background in the electronics ....I will be happy to hear offers how to treat this)

sorry for my bad english

Posted by: david on Friday, December 11 @ 16:48:19 MYT

David: can you test the output of the fm transmitter? as far as i know, the 2g does not have a protection circuit built in. Too high a voltage (>7v) will fry the charging chip (LTC4066)

If the chip is fried, your best bet would be to replace the board

Posted by: tzywen (http://tzywen.com) on Saturday, December 12 @ 14:41:43 MYT

OK, maybe somebody can offer some input, pin #1 = 5.02v, #2 = 2.49v, #3 = 1.99v, and #4 0 ground, what is going on, my ipod indicates thet nothing is going on, it isn't charging

Posted by: RPW1963 on Saturday, December 19 @ 05:59:33 MYT

Hi, guys,
I came to this page looking for iPhone 3GS external power solution that would be able to withstand continuous heavy load. Several folks complained that some car chargers (in particular Griffin PowerJolt SE) recommended in Apple store cannot keep up with power consumption of continuous 3G+GPS usage. My experience with running Trapster application in car shows that the battery fully discharges in slightly under 2 hours (it downloads Google maps ang uses GPS, plus I have bluetooth enabled). That means current consumption to be about 600 mA. I called Griffin Technology and they told me the PowerJolt SE is rated 500 mA. Then (knowing how to modify any USB supply for iPhone) I went to Fry's and bought a $10 Rhino USB car adapter with 2 USB sockets rated by 2A of combined output. I was surprised to learn that it works with iPhone 3GS right out of the box (even though it does not seem to claim so) using either its own retractable cable or cable that came with iPhone.

Today, I ran Trapster for about an hour while the 3GS was powered through the retractable cable that came with the Rhino adapter. My measurement suggests that the iPhone was drawing in average about 90 mA from the internal battery on top of power provided by the external supply (the battery got discharged by several %%). Because I believe that the power rating of the car adapter is not the issue it is reasonable to conclude that I am running into 500 mA limitation of the USB spec (while total current consumption was about 590 mA). So, the only hope is that the Apple engineers were diligent and provided a way to somehow enable the CLDIS feature discussed above (otherwise I would call it a design flaw).

I found that the Rhino adapter has voltages practically identical to that of the iPhone wall charger: 5V, 2.7V (not 2.8V as stated at the beginning of the page, but I do not believe it really matters) and 2V. The only difference is that the Apple charger provides 5.1V. However, the retractable cord only runs two conductors between the adapter and the iPhone connector, so it cannot deliver the D- and D+ voltages to the iPhone (unless an additional resistor divider is hidden inside the iPhone connector which I doubt). Can these voltages make the difference? Well, if I were designing this system I would consider using the D- and D+ voltages to differentiate between data port and wall adapter that has no 500 mA current limitation (e.g., D+ could be divided by 2 and connected to WALL/CLDIS logic).

Next time I will test the Rhino adapter with iPhone cable (and also iPhone wall adapter powered by 12-120V inverter) to see if it can resolve the 500 mA limitation. Stay tuned.

Posted by: Andrey on Saturday, December 19 @ 13:35:06 MYT

RPW1963: try #2 to be 2.7V . If my theory is correct and D+ is divided by 2 to get WALL signal then 2.49V might be not high enough assuming that real resistors in voltage dividers are not 100% precise.

Posted by: Andrey on Saturday, December 19 @ 13:46:15 MYT

RPW1963: make sure your 5v supply is stable under load. Most problems are caused by unstable power supplies that dip in voltage when the iPhone is connected

Posted by: tzywen (http://tzywen.com) on Saturday, December 19 @ 17:17:33 MYT

Andrey: Thanks for sharing your experience. I'll try to measure the current draw when the iPhone is charged by the factory charger. I'm assuming it's above 500ma because it charges way faster than my 500ma limited car charger. Will keep you updated.

Posted by: tzywen (http://tzywen.com) on Saturday, December 19 @ 19:54:39 MYT

Well, technically speaking, it is not very obvious how to translate current drawn at 5V from the external supply into battery current (whose voltage is 3.7V) because there must be intermediate buck/boost conversions. E.g., 500 mA @ 5V translates into 560 mA @ 4V (assuming 90% conversion efficiency). But I hope that the results will allow at least qualitative conclusions.

Posted by: Andrey on Sunday, December 20 @ 01:35:26 MYT

I ran two tests: Rhino adapter with iPhone cable and iPhone wall charger with 120V inverter. The results are inconclusive. First 40 minuts the battery stays at 100% and then starts discharging (down to 93% in next 15-20 min). I believe my first test showed same trend, but I thought it was my mistake. By the end of the tests the iPhone was pretty warm, so I start believing it is the heat issue. I read somewhere that when the device temperature elevates, the software stops charging process to protect battery (because charging generates more heat). If the most power-hungry components require low voltage, the iPhone may also choose switching to battery power if this strategy produces less heat. This theory is supported by observation that after a break (when the device had chance to cool down) the battery charge returned back to 100% even under same heavy use.

So, my recommendation under prolonged heavy use would be ensuring the device has chances to cool down. Take it out of the case, and if possible put in front of cool air outlet.

The results make me suspect that the 500 mA limitation (and the CLDIS feature) might even be irrelevalt, but to check that I need to cut the USB cable (to measure power supply current) that I do not want to do.

Posted by: Andrey on Sunday, December 20 @ 13:57:16 MYT

Andrey: very interesting observation there. going through the datasheet (page 6), there is actually a thermal protection that limits the charge current if it gets too hot. That maybe what's causing it to not charge.

Posted by: tzywen (http://tzywen.com) on Sunday, December 20 @ 23:16:34 MYT

tzywen: my primary point is that the thermal protection could force the iPhone to switch to internal power even when external power is available. Therefore, losing battery charge when connected to external power may have no relationship with the 500 mA limitation or CLDIS feature. I will collect more observations about the power behavior during my vacations.

Posted by: Andrey on Monday, December 21 @ 00:21:11 MYT

Gentleman, (Andrey & Tzywen) thanks so much for the info, when I get home from work this PM I will give it a try, thanks again.

Posted by: RPW1963 on Monday, December 21 @ 23:55:38 MYT

Andrey: yes, from what I understand, if it gets too hot the charging current is cut off so it runs on battery after that. sorry for not making that clearer in my last comment

Posted by: tzywen (http://tzywen.com) on Wednesday, December 23 @ 20:40:07 MYT

Andrey & tzywen, ok guys I have tried for pin #2 to get as close to 2.7v as I could got to 2.66 and 2.73 with negative results, no charging, any other suggestions and thanks for your time & help

Posted by: RPW1963 on Wednesday, December 23 @ 23:54:13 MYT

Guys, Excellent article.
Made the modification to my car charger, it's now working with the Iphone
3GS - Thanks...

Posted by: Rashid on Thursday, December 24 @ 17:12:07 MYT

RPW1963: I would do the following: 1. Make sure the both the iPhone and its USB cable (or whatever cable you are using) are fine by connecting to a working charger (i.e. the wall charger that came with the iPhone). 2. Doublecheck that the D+ and D- voltages are not swapped. 3. If #1 and #2 are fine then the only reason that comes to my mind is the one suggested by tzywen: make sure the power supply can withstand 500 mA load without lowering the output voltage. The easiest way to do that is to connect a 10 Ohm resistor and measure voltage over it. The problem that it will be dissipating 2.5 Watts so technically speaking you need at least 3 Watt resistor. You can use a 1 Watt, because you'll get enough time before the resistor will get hot (I believe 5-10 seconds). I would dare trying 1/2 Watt, but it may take only a few seconds before turning into a sigarette lighter, so I cannot recommend it (and if you do and burn your fingers or your table please do not complain). Another option could be using instead of resistor a 5V appliance that is known to consume 500 mA (connecting iPhone may not help because it does not charge so it most likely does not draw any current).

Posted by: Andrey on Thursday, December 24 @ 23:09:13 MYT

tzywen: sorry, I wasn't 100% clear either. I was assuming initially that when the thermal protection cuts off charging current the iPhone still takes external power to power itself. However we seem to be in sync now: iPhone not only cuts off charging current, but also switches to battery power. Few days ago I ran long test without protective case (to ensure the iPhone cools down easier). Air conditioner in car was set to 72-73F (about 22C). I didn't see much difference: the battery charge was going forth and back, but lowering overall. In 5 hours, 40% was lost. It probably means that the iPhone 3GS is not designed thermally for continuous heavy use (i.e. as a navigation device). Even though the observed discharging rate is adequate for everyday driving (even with aged battery) the question is if pushing Phone thermally to the point where protection kicks in does any damage to the battery. Interesting test could be using a computer fan to cool iPhone while driving. Maybe, I'll try some day in the future after vacations.

Posted by: Andrey on Thursday, December 24 @ 23:50:06 MYT

RPW1963: good thought arrives afterwards. If you solder in parallel five 51 Ohm 1/2 Watt resistors then you'll get what you may need to test your charger: a 10 Ohm 2.5 Watt resistor.

Posted by: Andrey on Friday, December 25 @ 04:06:33 MYT

Andrey and RPW1963: yes, loading your supply is a good way to test if your supply is capable of delivering the 500ma for the iPhone chargine. In many cases I've seen iPhones not charging because the charger simply wasn't capable of delivering the 500ma.

Andrey: Unfortnately I was unable to recreate the condition on my 2G. But with regards to your question on whether the battery would be damaged when the protection kicks in, I'm quite sure it wouldn't. Apple must have designed the device to be capable of handling the current and thermal dissipation during heavy usage.

A better test would be to put the iPhone in a fridge in an airtight container to prevent excessive condensation and then charge it under heavy usage and see if the protection kicks in.

Of course, with the test that you have already conducted, it has already shown that under normal operating condition, the iPhone wasn't designed to handle the thermal dissipation under heavy usage.

Posted by: tzywen (http://tzywen.com) on Saturday, December 26 @ 14:55:03 MYT

FYI, I've always used my HP Ipaq charger to charge my iphone, just had a look, it is +3.2 volts accross D+ & D-

Posted by: Paul on Wednesday, January 13 @ 09:14:12 MYT

Paul: thanks for the info! the HP charger has a female usb port?

Posted by: tzywen (http://tzywen.com) on Wednesday, January 13 @ 21:54:18 MYT

tzywen: has anyone ever confirmed whether there is a 4-resistor solution that will also allow USB data transfer? My computer provides voltage on USB when it sleeps, but nothing on D+ and D- so my iPhone 3GS stops charging. I'd still like my iPhone to charge when the computer sleeps, without the need to swap cables. Thanks.

Posted by: Polydactyl (http://www.nourl.com) on Monday, January 18 @ 02:20:16 MYT

Yep, HP Charger has female usb port... Just hacked a car charger I bought with the 2 resistor method, now my iphone charges in the car, and the Ipaq says 'AC' charging rather than usb charging (ie charges in half the time, its a 1000ma car charger), works with blackberry too!

Thanks for the site!

Posted by: Paul on Thursday, January 21 @ 07:56:05 MYT

Polydactyl: I haven't received any confirmed success with that yet. What I would recommend you to do is to use a changeover box. It's a box with a simple switch that will put the iPhone either to charging mode or data transfer mode.

Posted by: tzywen (http://tzywen.com) on Sunday, January 24 @ 13:11:07 MYT

Hmm...

It looks like my charger (an Alcatel ot-V770) works with my iPod. I belive they use the same IC, the LTC 4066.

Posted by: Ivan on Tuesday, February 02 @ 06:51:31 MYT

hey guys, am posting because my iphone is no longer charging from wall or synk to p.c
The strange thing is ,is that it charges from my music dock only. after reading this page i am thinking it might be only charging from the music dock becasue it may be putting out a higher voltage.
right now am trying to synk my iphone but it doesnt charge or connect but i am thinking i could splice my usb data cable so it would have two male usb ends and only one male iphone connecter end so it will feed the iphone more volts by being connected to my computer twice and hopfully make the phone charge n synk . what do u guys think about that . would it be to high of a voltage? thx

Posted by: chris on Thursday, February 04 @ 14:42:45 MYT

chris: have you tried with another USB cable? Or another wall charger for that matter.

Posted by: Tzy Wen (http://tzywen.com) on Thursday, February 04 @ 22:45:49 MYT

ye All wall chargers i have tried dont work and it not synk with any usb cable i have try. Only charge on music dock , shame my music dock dont have a computer usb port on the back or it

Posted by: chris on Friday, February 05 @ 04:26:56 MYT

chris: This is indeed very strange. I can't offer any logical explanation, except for the fact that maybe the other cables that you have tried are not functioning as well. Because as far as I know, if the iPhone charges on the music dock, it should charge through a cable

Posted by: Tzy Wen (http://tzywen.com) on Sunday, February 07 @ 04:14:46 MYT

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