Date: Sun, 6 Feb 2005 10:59:21 -0600 From: John Liu <[EMAIL PROTECTED]> Subject: Libretto Batteries - Rebuilding
Now that I have Win XP up and running on my L100, I notice that the Libretto will not run on either of my battery packs (hicap PA2503U and standard PA2502U). I think it was doing this before, when i last used the machine (1 year ago), so it is not a recent thing.
What happens is: the battery LED glows either green or orange, the Windows power meter says the batteries are 100% or 99% charged, but when I unplug the AC adapter, the Libretto immediately shuts down.
I have measured the voltage between the two end contacts on the batteries (one is marked positive, the other is marked negative) and this reads 6.4v (hicap pack) and 0.2v (standard pack). I have opened up the hi-cap pack and one pair of cells reads 3.7v, the middle pair reads 0.2v, and the last pair of cells reads 3.5v (these voltages are all approximate, I get a slightly different reading from my VOM with each measurement). So, I think the hi-cap pack has two bad cells and the standard pack has perhaps all bad cells.
I am thinking about buying lithium cells of the same dimension and capacity (ideally even the same make and model), unsoldering the bad cells, and rebuilding the pack. Has anyone done this? Are there any special tricks?
I see that I can buy a "new" pack for around $100, but I'm a bit skeptical - not sure how I avoid getting a used pack for my $100. I also found some places that commercially rebuild battery packs. What do you think about these alternatives?
Another thing I'd like to do is to better understand how the battery pack works. Why are there so many contacts in the plug and what is all that circuitry doing? The circuitry appears to monitor the voltage between each pair of cells, there's something that looks like a temperature sensor taped to one cell, and there's another component (a slim bit of black plastic) wired to the board.
Finally, is there a test I can do to verify my Libretto is working properly - I don't want to spend $50 or $100 on rebuilding or replacing battery packs and then find out it was a problem in the L100's power board.
