Post by gareth evans
PS. The reason that I keep the old Laptop is that it
has a parallel printer port and is the only means
that I have to occasionally use the HP Laser printer
when I need a hard copy that is not subject to water
Post by gareth evans
Old ASUS Laptop, about 7 years old, single CPU, Windows XP
Not really used, but kept in reserve, just in case.
I have a spare battery for it.
Every fortnight or so, I run it up to keep the battery
charged, and then swap the two battery packs and run it up
Usually, when the other battery is put in, it first
reports about 98% full before recharging to 100%
Strangely, the last two swap-overs, for both batteries,
when first run up, it says almost discharged at about 5%.
I think it unlikely that both batteries have suddenly
developed a high self-discharge rate when on the shelf
over a two-week period,
so this suggests to me that something must be amiss
with the Laptop itself.
Any clues, similar experiences out there?
You're right, you wouldn't expect both going bad at exactly the same
time. If you've always balanced the load between them, they'll wear
out at approximately the same rate, but wouldn't expect quite that
degree of synchronization.
Maybe the charger circuit is not adequately charging them?
Maybe the charge detection (probably by measuring battery voltage) has
gone bad? (Which could also lead to the charge stopping too soon
because it thinks they're full.)
You might try seeing how long one of those "5%" batteries will
actually provide power. One full discharge shouldn't unduly damage
them, and if you got 6hr or so that would prove the level shown was
Do they show the same 5% whether they're in the computer or out if it?
FWIW, charging to 100% isn't real good for Li batteries, they do best
if you avoid that last 10% full & empty. NiCd likes to be fully
discharged once in a while, and just topping off can lead to "memory
effect" reducing the amount of charge it will hold, but your computer
probably isn't so old as to have NiCds. NiMH have a normal
self-discharge of about 1%/day, and may need a full discharge/recharge
if they've been out of use a long time.