[blackmomba41]

when i charge my battery it will go up to 100%. then after a while it will go down to 99% and stay there, and sometimes go lower when plugged in for a long time. it doesnt go down fast, it actually takes a long time for it to go down past 99%, but i was just wondering if this was normal, for it to be plugged into an ac adapter and still have it go down after it has been fully charged.

[Tomchu]

This happens here too (12" iBook G4). Sometimes the "charged" state reads 99%, sometimes 100%. I've noticed that when the battery is very close to being fully charged (like 97% and up or so), plugging in the AC adapter doesn't charge the battery, it just maintains it.

I'm sure there's a technical reason for why Apple does this, so I wouldn't worry about it.

[phantomo]

Don't worry about it, it is totally normal. The PowerBook or iBook will not charge until it hit below 95%. If you consider the capacity of battery (i.e. 4500mAH), after fully charged, it is around 4500mAH, for example if it start to drop to 4498mAH, anything below full will show 99%. You can find some apps to monitor the capacity information if you want.

You should calibrate your battery if it gets very off. Follow the procedure on your manual.

[JoshuaZ]

Grab one of the many battery utilities off versiontracker.com they will help you.

[JKT]

The reason why Apple do this is because constant brief charging will radically reduce the life-span of your battery. Li-ion batteries gradually lose their charge (even when completely un-installed), so what would happen if Apple didn't do this would be for your battery to lose a bit of charge, get recharged, lose a bit of charge, get recharged, ad infinitum. Your battery would then be dead within a year or so, even if you never removed the AC adaptor. The 95% threshold is a compromise - it will take a while for it to discharge to that level, thus greatly reducing the frequency of the discharge/recharge cycle, but it allows for you to have an almost fully charged battery at any time if you decide to go mobile.

[hickey]

good to know, I noticed the same thing happening with my battery but I figured it had something to do with extending the life of the batt itself.

[rasmusnet]

The PowerBook or iBook will not charge until it hit below 95%.

The battery indicator on my powerbook never drops below 98% or 99% when being used with the adaptor plugged in. Are you sure it's dropping to 95%?

[phantomo]

Yes, I hardly boot my PowerBook and put it to sleep mode before traveling to and from work. That's how it eventually drop below 95% and start charging. It will take a long while for it to drop from 99% to 98% to 97%... until 95% while with adaptor plugged it.