Nexus 7 charges very slowly, even with 2 amp chargers I'm facing a rather painful issue with the battery life/charging issue with my Nexus 7 (4.2.2)


When idle and plugged into my 2A charger with the stock USB cable, it charges VERY slowly. I'd say under 10% per hour.
With just light usage over the course of an afternoon/evening, the charge got dropped to 50% (after charging it overnight and more).


I'm sure that something is wrong because no tablet should be performing that way (comparing to my other tablet, an iPad)

Update: I plugged my iPad1, iPhone5 and Nexus 7 into the same port on my Macbook Pro Retina. I've added a (mashed up) screenshot of all the 3 cases below and it's clear that the Nexus 7 never even demands anything above 500mA on a 2A port despite using the stock cable (and another microUSB cable). I'm now guessing this is a Nexus 7 firmware/software issue. Any fixes? That extra operating current should be 1600mA so it totals to 2.1A (="2A" ports).



Full resolution screenshot

Details:


Android v4.2.2 (stock image)
Settings => Battery 


Screen (77%)
Android OS (6%)
Tablet idle (6%)
WiFi (5%)
Maps (4%) (Maps isn't even running ... weird!)
Android System (2%)



I mostly use Chrome, Currents and Play Magazines so it's just light reading. I'm surprised those apps don't show up on the battery energy audit list (which is great compared to iOS BTW).

Question: What can I do to charge this device faster and use less battery? My expectations are anchored by my other tablet (an iPad) which charges a lot faster (2A charger again) and uses about 20% each day for casual reading vs 50% each day on the Nexus 7.
Two things to consider:

1 Depending on the charger, the Nexus might not recognize it as a 2A charger. It does not actually measure its capacity, but relies on some properties of the otherwise unused data-lines of the USB connection to the charger. Shouldn't be the problem if you used the charger that came with the Nexus.

2 It is possible that the Nexus is confused about the actual state of the battery. This can be re-calibrated, but is a rather involved process - especially if you don't have root on the device yet. However, guides can be easily found with Google.

Where does this leave you:


If you haven't used the charger that came with the Nexus, do so and see if problems persist.
If the charger is not the problem and you still have warranty send the device in.
If you are out of warranty try recalibrating the battery stats.