Battery drains even when plugged in while using Nav app on long road trips I have a Nexus S running Android 4.0.3 and Google Maps 6.8.1.

When I use the Google Maps navigation app, the battery slowly drains, even when plugged into my car charger.  After 5-6 hours, the phone will shut down due to loss of power.

I have already tried:


Using only 2G mode
Configured all of my (configurable) apps not to check for updates, fetch mail, etc, except when I tell it to.
Reduced CPU speed, changed CPU governor, etc


I've had limited success reducing the CPU speed too much, as it makes the nav app unresponsive when I set it too low.

I have not tried dimming the screen much, as I can already barely see it when driving with sun glasses on.

Is this normal behavior, or is my phone faulty (or misconfigured)?

What else can I do?


Perhaps there's a better way to charge my phone (different charger/USB cable?)
Perhaps there's some way to automatically disable the screen except when within a certain distance of a turn?  I.e. if the screen auto-blanked after 5 minutes, then would re-activate whenever there were spoken instructions, that would be fine with me.
Perhaps there's another nav app that's more friendly on the battery?


EDIT Even in my car, I use an A/C charger with a DC/AC inverter, rather than one of the round cigarette-lighter style chargers.
It's probably your charger.

I tested my Nexus S with the following:


dumb charger (only had +/- lines connected), capable of 2Amps (2.000mA)
Inlined voltage meter to measure currents
Brightness maxed, set CPU to 1.2GHz, performance governor, benchmark running


The device adhered to the USB standard and never draw more than 500mA (0.5A), although the charger is capable of 4x more current. It lost 2% percent during &lt;5mins when the benchmark ran.

I know that apple encodes power settings into their wall chargers by setting voltages to D+/D- pins of the USB connector. I'm not aware of how to tell the phone to just draw more power and dismiss the USB's 500mA safety regulation.

If you have such a charger, give it a try.

EDIT:
I could fix my own Nexus S' charging behaviour by using a kernel with force AC fast charge option enabled (for example Trinity kernel for Nexus S / Android 4.0-ICS) and this Fastcharge widget.