Thinkpads Forum

I charged up the 9 cell battery, did not use Thinkpad for 3 weeks and found the battery at 25%. Is this typical?

Li-Ion will loose /some/ charge on their own, but typical is much less then what you describe.

Ni-Cd: 10% after a day if not used, 10% more in 1st month sitting idle.
NimH: 30% in a month (but typically has 40% more full charge then Ni-Cd)
LSD NimH: 1.25% per month (LSD = Low Self-Discharge types)
Li-Ion: 5-10% per month. (This is normally due to the drain of the built-in voltage monitoring circuit when talking Li-Ion packs like in laptops)

If you store Li-Ion packs often, store them at 40% charge in a cool place (even a refrigerator is good ). They all have permanent loss, when stored at a rather warm 77F(25C) at 100% charge they have a permanent capacity loss of like 20%, this is only like 5% when stored at 40% charge.

75% is 3 weeks though seems WAY high, is it an older battery? Also was this 100% down to 25% or the proper storage of 40% down to 25%? Either way, still high loss. All this is if we are talking about Li-Ion... you didn't specify (My 760's take 9 cell NiMH or Li-Ion, my 701C takes 9 cell Ni-Cd or NiMH)

The battery is 3 years old but had never been used.

It's quite possible the battery is at only 25% of it's original capacity when it is "fully charged"

The chemical reaction takes place whether you use them or not... 3-4 years is often the lifespan of rechargeable batteries.

The gauge in the battery is probably lying to you, I have some older batteries that will charge and report 100%, but then I unplug the laptop and they drop to 0 within minutes.

Did you leave it in the laptop? If so, then it will drain a bit to keep certain wake-on-link devices powered.

Find a "Battery Meter" diagnostic software tool, e.g. Battery MaxiMiser (PC - Doctor, Everest??)

It will give you more information to help you decide whether the battery is worth keeping.

-- Full Charge Capacity
-- Design Capacity
-- Cycle Count

Power Manager supplanted Battery Maximizer, and has the functionality you describe.

could just be battery calibration being off too....
if the battery sat at full charge the whole time for 3 years - that is pretty hard on it! better to leave it drained for 3 years

i do have experiences with sanyos and sony "dying" from that - less than 50 cycles, and it would last until there is a bigger current draw on it, and it would jump to automatic shutdown... no amount of calibration could fix that - and battery info even reports a battery holding 90% capacity