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Subject: Questions about LiIon charger circuit and power drain
From: Christi Alice Scarborough (
Date: 2004-08-06


I was thinking it would be nice to try to make the battery percentage
for the V2/FM recorder a bit more accurate. Having had a look at the
charger specifications, I have a couple of questions that are beyond my
own hardware prodding ability.

1) The charger circuit has a PROG pin, which can be used to indicate
charging progress in the constant voltage stage of LiOn charging. Is
this wired up on the JB in such a way that V(PROG) is available to Rockbox?

2) What is the value of R(PROG) in the Jukebox? If I can find this out,
then I can work out what current is being applied in the constant
current stage of charging.

3) (Personal curiosity) If the circuit shuts down automatically, how
come my JB remains hot when plugged into the mains?

On a related note, how would I go about measuring the power consumption
of the Jukebox under several different conditions (ie idle, backlight,
disk access, playing, recording, radio)? I have a multimeter but
nothing else, really.

Oh, and while I'm here, my charger socket appears to be a bit up the
creak, in that I can only get it to charge by using an elastic band to
put the charger plug under tension so that it goes into the Jukebox at
an angle. Is there an easy way to fix this?



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