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Subject: Re: External battery pack options for FMR
From: Todd Lowe (
Date: 2003-08-13

> > I will say that 2-2.5 hours sounds very poor performance however. I
> > certainly get a lot longer out of mine. How do you charge the unit? Do you
> > remove the power as soon as the charge shows 100% in Rockbox? If so, leave
> > it overnight, as Rockbox currently shows 100% long before the charger
> > stops charging because the battery is full.
> >
> I agree. I listen to 200ish VBR and 256 CBR all the time on my player,
> and I generally get 6-10 hours with 1800 MAh NiMH's. I understand the FRM
> should have similar run-times.

I ran an experiment today with interesting results -- previously, I had
always gauged battery life from use on-the-go. Today, I started with a
fully charged battery, set it on my desk, and let it play undisturbed.
It ran for 4.5 hours, and still had 3.2V on the battery. I moved it to
another room, and when I plugged it into my stero connector, it went dead.
I tried to reboot it again, twice, but it didn't seem to have enough juice
to boot. I figured the batteries finally were spent. (BTW, I have
already applied the Rockbox flash to the rom, it works great, no probs w/
quick boot).

THEN, I plugged it back into the AC charger just long enough to get it to
boot (< 1 minute) and I unplugged the AC charger cord. The unit then
continued to run for 5+ additional hours, again, undisturbed, and was only
down to 2.8V when I had to leave.

So, I'm beginning to think it might be a loose battery lead inside -- when
I handled it to move it between rooms (and when I'm on the go), it must
lose its connection and die early ??? (i.e. at between 2-3 hours).
My conclusion is that the LiIon battery is not really that bad, its simply
a construction Q/C problem.

BTW, I have seen instructions on the web for taking the FMR completely
apart, resoldering connections, etc., to fix this kind of trouble but I've
never soldered anything, and I don't want to practice on my FMR. Not to
mention never getting the battery cover to stay on properly again...

> Do you have sane setting on things that eat batteries, such as backlight
> timeout and the like?

Yeah, the backlight is only on for 3 sec, and my file directory limit is
800 files (does this make a huge diff in the memory used for the song

Anyone that is tracking battery voltage change stats, I'd be glad to pass
on data from my FMR.


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