lruggier, on 24 April 2012 - 21:16, said:
Is it harmful to my laptop if I charge it up to 100% when it is just at 75% battery? Or should I wait for it to die until I charge it?
No, it isn't harmful at all. There could be some issues where the charge detection system isn't reporting an accurate % of charge, but charging a lithium ion battery from 75% to 100% should not harm the battery at all except that:
* The battery can only be charged a limited number of times (in-line with its "life" expectancy).
* You want to avoid charging the battery in a hot environment. So long as it isn't wrapped in a blanket or something, you shouldn't have this problem. But charging in a hot car, for instance, can really harm a battery.
Apple seems to say that it isn't full discharges that cause the trouble, but a deep discharge - for example, the result of a battery left fully discharged.
This is true about any lithium ion battery. The battery *shouldn't* drop below a particular charge or else its own internal circuit will be permanently damaged and incapable of holding any charge. For instance, if you have a digital camera that you rarely use and you forget to charge it last time so it is almost on empty and then put it away for a couple of months you will probably find that the battery is useless.