[Nexus 7 Accessories] chjade84:
There are so many threads on car chargers that actually work for the Nexus 7 and yet none of them seem to have reliable answers. Maybe it works, maybe not. Does it do "AC charging"? Is the amperage high enough to keep it running while I use it? Do I have to short Data+ and Data-? Does it work with OEM or aftermarket cables? Is it expensive?

It's enough to make you just want to keep the Nexus in the house. So I'm here to help - just go buy this:

http://www.amazon.com/dp/B0088U4YAG/ref=pe_175190_21431760_M3T1_SC_dp_1

Tom Fagerland was kind enough to provide links from Amazon UK, available in both black and white:

White: http://www.amazon.co.uk/PowerGen-Ch...ZY/ref=sr_1_15?ie=UTF8&qid=1351432753&sr=8-15

Black: http://www.amazon.co.uk/PowerGen-Charger-KeyBoard-Samsung-included/dp/B0088U4YAG/ref=pd_sim_ce_1

It's a 3.1A dual port car charger for $12.99 on Amazon with a full 5/5 review. I just got mine and it's well built, very sturdy (almost OEM quality) and has two USB ports, one for Apple devices "A" and one for non-Apple devices "NA". The "NA" port will charge the Nexus 7 and the "A" port will charge most other non-tablets, including the Galaxy Nexus. It works with the OEM Nexus 7 cable, a Monoprice cable and a Galaxy Nexus cable.

So that's it. Just go buy it and be happy. It will charge quickly if you leave the tablet off but will still charge it if you keep using it. :)

EDIT 2-11-13: This charger has been charging my Nexus 7 virtually every day (40 mins/day) for over 3 months now with no problems. :)

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For those of you wanting to know some more specifics, here they are. (You don't have to care, honest! Just go buy the thing.)

I did a test with my 7 starting at 40% battery. I did a "worst case scenario" of Wi-Fi on and connected, Bluetooth on, GPS on and using Google Navigation, Spotify streaming and the screen on at 100% brightness throughout charging. I powered the adapter off a variable DC power supply that shows current draw as well as voltage. I used 12.2 VDC to simulate a car's battery. Below is the relevant portion of the battery monitor graph.

It does indeed charge using the "NA" port with no modifications. The power supply showed an average current of 0.50A @ 12 VDC which once converted to 5 VDC is 1.22A not counting for the small loss in the DC-DC converter. It did get as high as 0.62A (1.51A @ 5VDC) but seemed to level out at 0.5A for the vast majority of charge time. (FYI I assume Watt's law applies here when stepping down voltage - feel free to correct me.)

I checked on the progress every 30 mins and here are the results:

00:00 - 40%

00:30 - 48% (+8%)

01:00 - 55% (+7%)

01:30 - 62% (+7%)

02:00 - 68% (+6%)

02:30 - 76% (+8%)

03:00 - 83% (+7%)

This is where I stopped. It seems to be very capable of providing a decent charge while under heavy use. At this point I turned everything off and waited another 30 mins and found it charged another 12% while "idle". At that rate it could charge from empty in around 4 hours. It would take around 7 hours to charge completely if being used heavily, but it's not just "maintaining" a charge or discharging slowly - it's actually gaining a charge.

So there you have it.