Set battery charging threshold to Custom, but T60 forgets

[Muse]

I'm running on a model 2504 mini dock, using 2 external monitors, one via DVI, the other VGA. Usually custom battery thresholds has worked but the last couple of days the T60 has seemingly forgotten that the charging thresholds were set to Custom. It went back to "Always fully charge." I noticed this in the battery icon in my tray, it was way above my target and climbing. Also, the thresholds in my custom setting had reset to far above my chosen start-charging and stop-charging limits (the thresholds had been reset to start charging at 96%, stop at 100%). Yesterday I reset it to Custom, entered my preferred thresholds and today it again reverted to "Always fully charge," etc. What might be causing this strange behavior?

[dr_st]

Did you take the battery out during this time?

[Muse]

No, the battery was in the whole time. Can't remove the battery without undocking the machine and it was fully docked the whole time. I'd done nothing unusual. I close the lid several times each day, putting the machine into suspend, reawaken by opening the lid. I don't recall anything else unusual happening besides the battery suddenly being on a fast track to "fully charged." It's an authentic T60 battery, I'm running WinXP.

[precip9]

I seem to recall from experiment that when a battery is swapped, as long as it is a genuine Lenovo battery, the charge thresholds follow with it. This would imply that the battery has a memory for a few bytes, which makes sense, since it has a small microprocessor that is part of the "keep-alive" circuit.

So you might have a battery with a defect in that area.

[Muse]

I seem to recall from experiment that when a battery is swapped, as long as it is a genuine Lenovo battery, the charge thresholds follow with it. This would imply that the battery has a memory for a few bytes, which makes sense, since it has a small microprocessor that is part of the "keep-alive" circuit.

So you might have a battery with a defect in that area.

The particular battery came with a factory refurbished T61. It has a little less capacity than the battery that came with this T60 (bought new end of 2006). That battery I have in my refrigerator in hopes of extending its life.