How to Make Your Own USB Car Charger for Any IPod or Other Devices That Charge Via USB




Create a USB car charger for any iPod or other Device that Charges Via USB by splicing together a car adapter that outputs 5v and USB Female plug. The most important part of this project is to make sure that the output your chosen car adapter is between 4.75v and 5.25v otherwise you risk damaging your device. Please verify voltage with a voltmeter.

Step 1: Introduction

Note: I have tested this only on an iPod Nano, but I would imagine that It would work for any iPod that charges via USB, or any device that charges over USB that uses a 5v source for charge.

The basic idea here is to charge my Nano via USB while in the car. The total project cost for me was Free-99. I had all the spare wiring and cables because I never throw anything electronic away. I did however build another one for a shade under $8 bucks. I mean thats not terrible for a car charger for your iPod and other USB chargeable devices. Plus its fun to DIY.

Typically, your USB port provides 5v of power through a single wire in a 4 pin USB cable. The normal operating voltage for most USB devices is between 4.75 V and 5.25 V. Ok great we understand that, but now how to get 5v from the 12 volt source (your car)? I stumbled upon this idea by accident, literally, I tripped over my wall charger for my Nextel-Motorola i870 and noticed that the adapter has an output of 5v to charge the phone. So, I went outside to my car to check the output voltage of my car charger, it was unmarked, so off to the Wal-Mart that is across the street I went to pick up a multi-tester. Upon testing the voltage output of my car charger I was astonished to see that sure enough the output was 5.15v well within the range to charge the iPod.

Read that last part again, I verified the voltage on a voltmeter. I also tested several other car adapters I had laying around, and the output voltages varied greatly, from 3v to 14v. So unless you are positive of the output voltage dont just splice away expect to get the right voltage to your iPod. (on a side note I also constructed a Firewire wire alternative from the aforementioned 14v car charger, and a tutorial for this one is coming soon). After verifying that the voltage was within normal USB operating range I used a USB extension cable to get a female USB plug. The next steps follow logically, splice USB female end to car adapter wires, seal, test voltage, go plug in. Direction and some pics follow.

Step 2: Parts and Equipment List

Parts and Equipment list:
- Motorola Car Charger for i205 i305 i315 i325 i530 i710 i720 i730 i733 i740 i830 i860 i870 cell phones.
Any car charger that has an output of 4.75v to 5.25v. (Note: I also used a Belkin Mobile Power Cord (#F8V7078-E-MK, $7.68 at Wal-Mart) which has an output of about 5.8v and it works fine as well, but to be safe, stay in the 5v range so you dont burn out the voltage regulator in your iPod. Also, be sure that your car charger has some sort of fuse protection)

-USB extension cable USB A/A M/F (you should have a least one of these somewhere)

Some sort of USB connection to your iPod I use an Apple iPod Dock Connector to FireWire and USB 2.0 Cable for everything that I do with my iPod, as its the only dock connector I own.
Voltage Meter

Soldering iron, Solder, heat-shrink tubing

A pair of cable strippers


Step 3: Step 1

Step 1: Verify that your chosen car adapter has an output voltage of 4.75v to 5.25v while plugged in. (USE Voltage Meter)

Step 4: Step 2

Step 2: Unplug and cut the piece that plugs into your phone off. Strip the wires to expose the red and black wires.

Step 5: Step 3

Step 3: Cut Female end of USB plug off of the USB extension cable, leaving about 8 inches or so to make room for error, and ease physical stress on your solder joints.

Step 6: Step 4

Step 4: Strip the USB cable so that all shielding is removed exposing only the 4 USB wires. We are only concerned with red and black so cut the green and white wires as close to the bottom of the area that you stripped, as possible

Step 7: Step 5

Prep wires with heat shrink tubing (I forgot the first time, only to remember after soldering everything together, and I had no E-Tape)

Step 8: Step 6

Solder red to red and black to black. Cover the joints so they dont short out, then heat shrink the whole thing to keep the joint protected.

Step 9: Step 7

Plug into cigarette lighter and verify voltage again. The pin-outs are located here ( just in case you are unsure. If everything checks out, plug your iPod in and charge away

Step 10: Follow Up

If you are comfortable with this type of set up, but would like to use a Firewire cable instead, use an adapter that has an output voltage of 12v to 30v. I have several adapters that output 14v constant, these are ideal to splice with a Firewire female wire. Coincidently, this cable ( would also allow you to mount the connector in the car (in dash, flush mount, console, or otherwise) and you can also hardwire if you wish.



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    98 Discussions


    5 years ago on Introduction

    This article is 7years ago.

    Now, I think one new product can solve the problem.

    There are already dual ports USB car chargers. Here I suggest one on the web:

    You can see, there are already two ports output, it is enough for the normal use on the car.

    And there are also 3 ports or even 4 ports output car chargers if you would like to search on google.

    Anyway, thank you for the share! It is good article in 7 years!


    11 years ago on Step 6

    What are the blue(green?) and white wires? Just ignore them? Thanks

    2 replies

    Reply 11 years ago on Introduction

    These are your data lines. Sometimes they must be biased or terminated in order for the device to be recognized. This is especially true for the iPod.


    Reply 7 years ago on Step 6

    I highly recommend checking out this article from AdaFruit. It goes over the design of a USB charger and explains what different voltages on the data lines mean.


    13 years ago on Step 10

    Since making this I also realised that 2 other things could be done in this manner. First, you could make an extra wall charger by using the motorola wall adapter (Model:PSM4680A) since it also has a 5v output. Secondly, you can use the unused male end of the usb extension cable spliced together with the part that plugs (the part you clipped off) into the phone, and still use the charger as a phone charger as well, simply plug the male end back into the female USB end and presto, you still have a functioning car adapter for your phone.

    4 replies

    Reply 12 years ago on Step 10

    could said charger use 4 aa batteries... i know that equals 6 volts but then you could slap on a capacitor or resistor to make it 5v?...


    Reply 7 years ago on Step 10

    (Yes, I know I am 6 years late to the party. It's for future reference)
    USB chargers should output between 4.75 and 5.25 volts, and for full charging efficiency 1900 mA (Any set of batteries will provide more than that. Over-amperage won't damage your devices, as they will just pull what they need). Low power USB devices should be able to work with as little as 4.4 V, and all devices should be able to signal, if not work.
    Now, a standard disposable battery is rated as outputting 1.5 V, and will at most of it's useful life, but when they are brand new they use to output as much as 1.6 and 1.7 volts, and they go down as they discharge. Most devices are aware of this and will work at 1.2 volts and up. Rechargeable batteries output at less voltage (Fully charged at 1.4 or less and for most of its use before recharging at 1.3 - 1.2), but have a less step voltage diminution graph.
    Down to the math:
    Brand new alkaline outputting 1.7:
    3x1.7=5.1 (OK)
    Brand new alkaline outputting 1.6:
    3x1.6=4.8 (OK)
    Less batteries you are too low, more you are dangerously high.
    Used alkaline (1.5):
    3x1.5=4.5 Low, but usable (-0.25v)
    4x1.5=6, way too high (0.75v)
    fully charged rechargeable (1.4):
    3x1.4=4.2, too low (-0.55)
    4x1.4=5.6, too high (0.35v)
    Somewhat used rechargeable:
    3x1.3=3.9 too low (-0.85v)
    4x1.3=5.2 (OK)
    Used rechargeable (1.2):
    3x1.2=3.6 way too low (-1.15v)
    4x1,2=4.8 (OK)

    Most devices will have higher tolerances than the USB standard requires, but the question is ¿Do you feel like risking? In any case, under-voltage is much less likely to do damage than over-voltage.


    Reply 7 years ago on Introduction

    It would be much easier to just use a zener diode and a resister in parallel with the diode on the + end, as a voltage regulator


    Reply 8 years ago on Step 10

    Yes, I think it is much possible. Probably won't get a lot of time, but will work great for an emergency charger for your usb phone.
    Check this out:
    for details on how to calculate the amount of resistance needed.


    7 years ago on Introduction

    This post is relative specifically to HTC phones and I assume similar problems affect each specific device.

    I've been researching this for a while as the HTC Desire is quite choosy about pulling >500mA (indicated on the phone as "AC Charging" rather than "USB Charging").

    This whole thread goes into very good detail but this post in particular covers the issue nicely:

    Adding resistors (max 200ohm) to the data pins will cause the Desire to assume it's connected to USB computer and therefore the phone will not try to draw more than 500mA. Indeed, it seems using a long cable (2m) may provide enough resistance to fool the Desire. So ideally, you want to short the data pins at the microUSB end. That's easier said than done, so you may have to experiment with a few different cables. YMMV and it seems everyone's does.

    The basic points are that to get more than 500mA into your Desire, you need a car adapter capable of outputting enough current, and a good quality cable with the data pins shorted.

    I would assume this applies to all HTC phones and perhaps many other devices.


    7 years ago on Introduction

    Simpler, yes. Powerful enough to charge high current devices, such as the iPad or HTC Desire, no.


    10 years ago on Step 8

    This is great and is what I made this weekend (On my own, before I saw this.) The differences were that the first time I did not connect the data lines in the USB cable. This caused my Blackberry to not charge. I changed the data lines to ground. This lets the device charge for about 5 seconds, then it quits. Is there something else that needs to be done with the data lines? This same unit was used with a e200 series sansa. The unit did not charge with the data lines disconnected. I haven't tested the unit with the data lines to ground yet. I am able to use other USB powered devices with the cord. This Belkin unit is great for this job as it puts out good voltage -- it did a great job of charging my Motorola cell phone.

    2 replies

    Reply 9 years ago on Step 8

    yes u have to connect ur data lines with a certain connection not simply grounded to start charging i've tried the above connection for my iPod classic and it didn't work i don't know the exact connection that u need for ur phone but i'm sure that u have to connect the 2 data lines correctly


    Reply 7 years ago on Step 8

    For the HTC Desire, simply fusing the data wires tells the device it's plugged into AC power, so it draws more current than the 512mA USB maximum. I imagine it's specific to each device though.


    7 years ago on Introduction

    Sus out this Video on Iphone charging very informitive


    7 years ago on Step 10

    Not to put a damper on the build... but just wanted to share the option that you can buy a pre-built, clean, ready-to-go cig-USB adaptor on ebay for $2.38 with shipping... (or about $4 from US seller). Nice DIY, but just wanted to throw the option out there.

    1 reply

    8 years ago on Introduction

    great instructable, once i find the appropriate charger i'll give this a shot. i was planning on putting the circuitry in a small enclosure, hard wiring it to my accessory power, then putting a switch to turn it on and off when i need it. i'm pretty sure just putting a switch into the circuit would burn out the circuit (as this has happened plenty of times to me) so how would i work a switch into the circuit?


    9 years ago on Introduction

    I just finished a DIY solar usb charger, specificially for my iPod. I already knew that USB voltage varied from 4.5 volts to 5.5 volts.

    My multimeter reads right now 5.20 or very close to this; I'm inside and it's night outside. With multiple lamps, that's what I'm reading. Yet my iPod is plugged into my female USB plug (salvaged from a dead motherboard) and nothing shows up.

    I used this page for the usb pinouts:

    What could I be doing wrong? :O Not enough milliamps outputted makes the iPod think it's still not plugged?

    I also tried on a completely dead (battery) iPod, no results..

    Thanks for any further help!