I did this for a friend because he always had his AC adapter plugged in and so the battery was fried
There's a lot of controversy over that too - with no conclusive proof at all that leaving the charger plugged in will damage or shorten the life of the battery.
I bought my Toshiba notebook in Feb 2010 and it stays plugged in all the time and the battery still works just fine. Maybe
once every couple months I unplug it and let it run down, but that's it.
Notebook charging circuits are designed to prevent over-charging the batteries as that could create a fire hazard. Even the batteries themselves (at least the genuine, non-counterfeit batteries) are designed with protective devices to prevent over-heating. So leaving them
plugged in will not cause a battery to "fry".
And Lithium Ion batteries don't suffer from memory effect anywhere near the extent old style Ni-Cad batteries do. Now all
batteries do weaken over time resulting in shorter run times. And of course, some can just fail prematurely due to a defect or some other electrical or physical abuse.
My 17" Toshiba used to run for 2 hours on a full charge, now it is about 90 minutes. But that decline is typical for a nearly 6 1/2 year old battery.
Most notebook userguides do say to not leave chargers plugged in all the time. But as an electronics technician for 45 years, I truly believe that's the company's lawyers talking. You look at the manual for just about any electronics device, it will tell you to unplug it when not in use.
For example, I just bought a new Cuisinart coffee maker. Look at the manual here
and note right off the bat on page 2 (the cover is page 1) in big bold letters the first two "IMPORTANT SAFEGUARDS".
1. READ ALL INSTRUCTIONS.
2. Always unplug from outlet when not in use...
11. Always fill water reservoir first, then plug cord into the wall outlet.
Note this is a programmable coffee maker with a built-in clock that lets me prepare the coffee before bed, then it automatically switches on so I can have my hot coffee when I wake up. Do they really expect users to unplug the coffee maker after drinking the coffee each morning, then before bed, fill the reservoir, plug it in again, re-reset the clock, then reprogram the brew time? No.