Laptops if you leave them plugged in?

The built-in charge management circuitry will prevent overcharging. Don't worry about that.

Heat is the great enemy of laptop batteries. The inside of a laptop can get quite hot, especially if you're gaming.

I'll recommend that, if you're going to run the laptop for extended periods while on AC, you first remove the battery pack and set it aside. You'll get more life out of it that way. Not a huge amount, though: maybe 2.5 years, instead of 2 years.

I just answered this two minutes ago for someone else, so here's a recap...

1. YES, when the machine is left on (or even when it's turned off) the battery will be "tested" for voltage and current. This "test" spends a tiny bit of battery reserve in the process and will eventually take the battery from 100% to 99.something percent and eventually trigger the charging circuit to begin a cycle.

2. The charging cycle in many laptops is time based (ie: Charges for 5 minutes or so and then does a test again to determine voltage/current.) If the battery was only drained to 99.9x% and triggers, there IS in fact the ability to overcharge when in this situation. (Under normal conditions when using a laptop for its portability, it's using the battery where it's much less than 99% when the next time comes around it gets plugged back in.)

3. When this charging cycle is repeated over and over, it WILL cause the battery to feel hotter than average due to the excess current going into it to try to run a charging cycle. This heat will expand the tungsten and graphite within the battery which makes the materials more brittle and thus allows less current to be stored.

Ways to help prevent stagnant batteries:

1. Have a laptop "Cooler" placed under the machine while it's being used more like a PC than a laptop (ie: used while plugged in.) This will help distribute heat away from the machine and help prevent battery as well as laptop heating problems.

2. When you're planning to use it as a "PC" - pull the battery and sit it aside once it hits at least 90% or more charge. When you need to go portable, simply plug it back in. (Check the owner's manual as to whether or not it's "required" to have the machine powered off or the charger disconnected when hot-swapping batteries.)

Hope this helps!

Does what??

Is there an image? Sorry I'm on an iPod