Battery at 25% after nonuse

[JerzeeDevil]

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

[ozzymud]

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)

[JerzeeDevil]

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

[ozzymud]

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.

[Colonel O'Neill]

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

[robert213]

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

[Colonel O'Neill]

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

[slpin]

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