unused five year old battery OK?

[mikeh]

Or have I been had? Bought a "new" thinkpad battery that was made almost 5 years ago.
I was almost surprised that it worked at all, but it seems to hold a full charge.
I got the rated 2.5hrs use and ACPI reports 98% of design capacity after one cycle.
What are the chances that it will keep working for long?

It is a 4-cell flat battery for X-40, not cylindrical cells, so I assume Li-Po?
Will be nice if it keeps working, as it lasts just as long as my old 8-cell does now, and cuts the laptop weight to a net-bookish 1.2kg. (2.6lb)

[dr_st]

I got the rated 2.5hrs use and ACPI reports 98% of design capacity after one cycle.
What are the chances that it will keep working for long?

No one will be able to tell you for sure. The variance in battery degradation over time is really big, from my experience. It is as likely to hold that charge for 2 years, as it is to start losing charge rapidly within a few weeks.

I have here a 6-cell for a T60, manufactured by Panasonic, in Jul/06, first used in Aug/06 (3 years ago). Then it probably lay in a closet at 0% charge for 2.5 years, because when I found it a few months ago, it was completely discharged with 3 cycles on it, and held 93% of the design capacity. I've been using it regularly (albeit sparingly) since then, and now it shows 41 cycles, and 96% of the design capacity.

My limited experience showed that Panasonic batteries tend to fare better over time than Sanyo batteries, at least those from the T4x / early T6x era. They lose their charge almost linearly in time and use. Sanyos tend to hold a very good charge for about 1.5 years from manufacturing, regardless of cycles, then start losing it rapidly... Sony batteries are a mystery to me, as they are not as widespread as the other two.

[mikeh]

Thanks for the reply. It is a Sanyo Will keep fingers crossed.

[tporter]

I bought that 'new' 4-cell battery (for X41t) too
Manufactured Mar/05, 1 cycle count, Sanyo cells. Was deep discharged on arrival.
After 3 cycles it still shows ~107% of design capacity...

I think it isn't Li-Po, maybe the same Li-Ion but with smaller cells