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Subject: Battery levels
From: Magnus Holmgren (
Date: 2002-08-25


The battery levels in powermgmt.h, where they measured on a Recorder?
The reason I'm asking is that on a player, the full charge voltage seems
to be a bit higher...

I just measured playback time - under ideal circumstances - with some
new 1800 mAh batteries (I got close to 12 hours), and wrote down battery
voltage and level from time to time. Note that the voltage fluctuates a
bit, so the readings aren't that accurate. However, I got some
interesting reults:

When starting (from fully charged batteries, as reported by the ROM
firmware), the voltage was about 5.60, with peaks at 5.70. It took about
1 hour, 45 minutes to reach 5.20 volt, the "full" level in powermgmt.h.
A few other readings of interest:

4 hours: 89%, 5.13 volt
6 hours: 80%, 5.09 volt
9 hours: 56%, 4.95 volt
11 hours: 21%, 4.75 volt

Let me know if you're interested in the full data set (about 25

I haven't done the same extensive test with the standard 1500 mAh
batteries, but I think it took a while before the level started dropping
below 100%...

Magnus Holmgren

Page was last modified "Jan 10 2012" The Rockbox Crew