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.
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.
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: http://www.usbcaradapter.com/products/dual-usb-car-charger.html
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!
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.
Check this out:
http://www.ehow.com/how_4900110_reduce-voltage-resistors.html
for details on how to calculate the amount of resistance needed.
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: http://androidforums.com/htc-desire/75062-charging-usb-ac-differences-4.html#post2980915
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.
http://www.ladyada.net/make/mintyboost/icharge.html
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: http://pinouts.ru/Slots/USB_pinout.shtml
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!
(I'm great reader but really bad english writer)
Hopefully you aren't thinking that this is a USB port for your car, because then you probably didn't read the instructable, or just deserve a big facepalm.
http://www.dealextreme.com/details.dx/sku.688
This thing works great, uses a small buck regulator.
and you can mod it for you needs.
http://www.amazon.com/gp/product/B000FAQ6S0/sr=8-1/qid=1205860693/ref=pd_cp_e_1?ie=UTF8&qid=1205860693&sr=8-1&pf_rd_p=250314601&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B000UHS82U&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0A96TM09BN673GHV7272