Should laptops remain plugged in when their battery is 100% charged?

"This page has a good answer: ""it depends""

The answer is: YES and NO, it depends
on the situation.

Having a battery fully charged and the
laptop plugged in is not harmful,
because as soon as the charge level
reaches 100% the battery stops
receiving charging energy and this
energy is bypassed directly to the
power supply system of the laptop.

However there's a disadvantage in
keeping the battery in its socket when
the laptop is plugged in, but only if
it's currently suffering from
excessive heating caused by the laptop
hardware.

So:


In a normal usage, if the laptop doesn't get to hot (CPU and Hard Disk
around 40ºC) the battery should remain
in the laptop socket;
In an intensive usage which leads to a large amount of heat produced (i.e.
Games) the battery should be removed
from the socket in order to prevent
unwanted heating.


The heat, among the fact that it has
100% of charge, is the great enemy of
the lithium battery and not the plug,
as many might think so."

"This all depends on the type of material the battery is made out of. Each battery material has different ideal characteristics. Look on your battery label and determine the type of battery it is. (i.e. lithium-ion (Li-ion), nickel-metal hydride (NiMH), nickel-cadmium battery (NiCd), etc. Once you determine which type of battery it is simply google the material, and read about the capabilities. This should tell you all and more of what you would like to know.

A note on charging.. Not all charging circuits are created equal, so if you have a deficient charging circuit, you might indeed want to unplug the battery after it has been fully charged like was suggested above."

I remember something from Nokia about how leaving mobile phones plugged in after they were fully charged caused an increase in overall energy usage, as compared to unplugging when charged and recharging when needed. This was part of some green initiative. I would imagine that laptops are the same. Therefore, by leaving your laptop plugged in while turned off and fully charged, you may be increasing the size of your electric bill.