Modify a generic USB car charger to charge a 3rd gen iPod Nano

I have a 3rd generation iPod Nano. It detects it's connected to but refuses to charge from a generic car->USB charge adapter, but I didn't fancy buying an adapter cable or yet another charger specifically for the iPod, so I modified one I already had.

There's a chance that this could work for other USB devices (maybe an iPhone too, but I don't have one), but there's also a chance that this could fry your device, car, or perhaps eat all of the cheese in the house. If you're not confident, or not competent, you probably don't want to try this. I accept no responsibility for any bad things happening.

If you're vaguely interested in stuff like this, you should probably check out ladyada's MintyBoost! kit, which helped prod me towards actually doing this.

Step 1: Bits needed

You shouldn't need more than the fairly standard soldering tools, a multimeter, and a couple of resistors (not shown) -- I grabbed a couple of SMT resistors from an old CDROM drive.

If you want the very simple steps without any instructions, all I did was connect a 27k Ohm resistor from V+ (Pin 1) to D- (Pin 2), then another 12k Ohm between D- and D+ (Pin 3). Dead easy.

Comments

[Leinho]

I am trying to do this with my iPhone 3G ... Cause the car charger does not charge.. I was about to do this with an usb extension.. rather than doing it right in the usb adapter.. I dont know which ammount of Ohms i need in every REsistor,.. i thought 100 ohms is fine.. Please tell me.. Regards

[techboy411]

Stupid IPhone 3G, these are very picky about the charger used

[davis65536]

I think you probably want higher value resistors -- something in the 10s of thousands of Ohms range

[chooper1]

Can you tell me what the voltage measurements should be for the two data pins to ground? Cuz when I measure D- to GND and D+ to GND, i'm getting close to the full voltage that I get from V+ to GND, which doesn't seem right... but maybe it is.

[davis65536]

Yeah, that sounds about right; you won't get a huge voltage drop across those resistors, but from your message it sounds like you've achieved success anyway!

[h00ch]

Does anyone know if this will charge a PS3 controller?  "Normal" USB chargers do not work.

[geraldrubalcava]

i think you should try it. because the ps3 is unknown what are the pullup resistors it needs to use.

[danielemur]

does this work with ipod touch?

[davis65536]

Very probably.

I'd really be surprised if it didn't; it works for the iPhones and for every other iPod I've found.

[mopk47]

with 3 resistors added between 4 pins, works well according to simulation and actually test. the value of resistors would be: 5V-39k-12k-33k-GND. This config with produce a nice 2.7V and 2.0V.

[acaz93]

it works for the iPhone , too !

[endolith]

iPods don't follow the USB-IF charging spec. They use voltages on D+ (2.0 V) and D- (2.7 V) to tell the iPod how much current it's allowed to draw. You can just measure the pins on a Griffin charger or whatever to test this.

Cell phones don't follow the USB-IF charging spec, either. I'm not sure if anything does. :)

[khem2356]

what is the resistor valua? in ohms

[davis65536]

Errr... From step 1 of the instructable: If you want the very simple steps without any instructions, all I did was connect a 27k Ohm resistor from V+ (Pin 1) to D- (Pin 2), then another 12k Ohm between D- and D+ (Pin 3). Dead easy.

[khem2356]

is this how it connects?

[davis65536]

Well, assuming pin 1 on your diagram is V+ as it appears to be, then yes, that appears to be correct.

[khem2356]

i did mod my usb charger, and it did work on my ipod vedeo classic. lol! thanks a lot!!!!

[davis65536]

No problem. Glad it works.

[gamer]

Thanks a lot!! Works for Sansa E2xx series! :D

[davis65536]

Good news! Glad it works for you!

[redlegoman]

This works for the ipod classic too. It's the resistors to the usb data lines which are important here.

[davis65536]

Ah cool, thanks for the info.