When I recharge my mobile phone it usually takes 2 or 3 hours. After that the phone tells me the batteries are full. My dad, however, tells me to keep the phone charging even if the batteries are full. I've done this once and noticed it lasted longer. However, it was a short-term phenomenon because after a few weeks the battery ran out more quickly and I needed to recharge it more often. However, I don't know whether this increased rate at which I need to recharge the battery was caused by overrecharging the phone or whether this naturally happens because the battery is getting old. Can someone tell me whether overcharging a battery is harmful? What is the reason for it?

 

Generally overcharging batteries causes them to die sooner. In most hybrids I believe the batteries range is between 40% to 80% charge to get the most out of them.

 

I've had several Li-ion camcorder batteries refuse to take a charge. The camcorders were always plugged into their AC adapters. Since the camcorders can run off of AC with the batteries removed, that's probably what I should've done.

I've seen a few laptop batteries develop the same problem in laptops that were always run off of AC power.

My laptop battery is fine after the same amount of time. I run down the battery from time to time even though AC power is available.