Battery died while plugged in to high-power usb port.

Erik esw at alum.mit.edu
Sun Aug 5 18:41:23 CEST 2007


This morning I woke up and found I couldn't turn on my neo... even
though it was plugged in [usb] all night!  It was plugged in directly,
as in no hub, and yes, the PC was on overnight.

I'm not sure what happened... I was playing with gsm and bluetooth
[ssh'd in over bluetooth] when I powered it off.  I probably just put
it to sleep, actually, not hard off.  So possibly the bluetooth was
still on drawing power, and maybe the gsm was still alive, and the cpu
was keeping its memory warm too.  So possibly this was taking more
than 100ma?  I didn't even think I had anything to worry about since
it was attached to USB 5V that should be able to put out 500ma.  I
figured it'd be fine to leave it in that low-ish power state
overnight.

I'm attempting to charge the battery now, the Neo 1973 emergency
charging way listed on 
http://wiki.openmoko.org/wiki/Neo1973_Battery_Charger So I have my
fingers crossed that it'll come back to life.  


Bunch of questions:

1. Has this happend to anyone else?

2. Is there a way to double check the charging rate from software?

3. Should a voltage always appear on the +/- terminals of the battery,
   or does that third pin need tickled in some way to get a voltage
   out?

4. My battery reads 0 volts between +/-; is that battery toast?  I
   know Lion's can be ruined if they're discharged below a certain
   voltage per cell... because they may grow internal shorts and then
   overheat/explode on recharge.  Unless they have a built-in
   resettable low voltage disconnect [LVD].

5. Does our battery have a built in LVD?  It worried me when I noticed
   that several subsystems [the audio driver for one] get Vbatt.  I
   hope there's a LVD somewhere or else I probably will need to buy a
   new battery somewhere!

Any ideas?

-erik



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