GTA02 Battery Capacity (Was: Re: More about the GTA02)

Andy Green andy at
Sat Mar 1 03:44:47 CET 2008

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Somebody in the thread at some point said:

> Ok about charging, but what's exactly now the status of "discharging" on
> GTA02 devices?
> I mean... How long is actually running a (pre-)Freerunner without
> charging it?

Depends on what you're doing with it... is the backlight on all the
time... making a call... I can't give you a straight answer because I
didn't examine this yet.  Instead I spent all my time around power
consumption looking to optimize suspend current since that can involve
circuit changes.

For suspended time with GSM modem off we have the consumption down to
~2mA and I expect that will improve further by software changes, so on a
1200mAh battery like we ship maybe it can last 20 days (unverified!)
doing nothing at the moment.  With GSM modem on in suspend maybe 5 days

Whatever the figure is for "usage time" it will change by a factor of 5
or 10 depending if you run the GSM transmitter, wifi, CPU is always
busy, GPS, and the worst suspect the backlight, so you need to define
exactly what you do with the device during this "usage" to get a
meaningful figure.

Generally I would expect over time we can improve performance in
software, like dimming the backlight gently quite soon after the last
action, getting the backlight off quickly, and getting into suspend
quickly between actions from the user.

- -Andy
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