Laptop battery?

It's a really hazy area. Many people will tell you to keep the battery in. Many will also tell you to take it out.

I personally take the battery OUT whenever the laptop is plugged in, except when i'm charging the battery.

My battery has retained it's full performance over the period of 1 year by doing this.

Many of my friend that I tell to take the battery out when you plug the computer in even if it's charged to keep the battery at full performance.

They don't listen and after 6 months, they start telling me their battery is terrible, and it barely lasts 30mins.

The reason being is, the laptop will always "trickle charge" the battery, and keep it topped up at 100%. That's not a good thing to do.

The battery life will slowly die.

Many people will tell you that it's not true, and to keep the battery in. There's "digital circuits" that stop the battery from charging.

Nothing stops the battery from charging unless you disconnect the battery directly.

Those who don't believe taking the battery out yourself, do your own test.

Do a test for 1 year on 2 batteries. One left in, one taken out when ever you use AC power.

I guarantee you the one taken out, and only used when you need battery power will retain more performance.

As sizzlincok pointed out, this is really a grey area, opinions differ and you will never find out a consensus. 

I've owned a few laptops over the years, being the latest one an HP Pavillion bought 3 or 4 years ago. Just like you, I always keep the battery in and my laptop is almost always running on AC power (and never runs on battery power more than 10 or 15mn). There was only one year when I used my laptop mostly on battery power until almost empty.

Regarding lithium batteries and my experience, there is nothing wrong with keeping the battery in. I've lost between between 2 and 4% of capacity every year in the HP Pavillion, which is remarkable. What really did affect A LOT my battery capacity was the year I used the laptop mostly on battery power until it almost ran out of energy. That year alone costed me around 30% of my battery capacity.

There is also a Packard Bell in the house (with similar specs and more or less the same age) that runs on battery a lot more, but usually it is plugged in to the wall socket when it reaches 40 or 50%. That one lost around 20% capacity in the last year. I also have an older Asus that I would indeed remove the battery when plugged in, but when it ran in battery power, it would run until 5-8% battery power was reached. That battery completely died in about 2-3years.

Conclusions regarding my personal experience: In modern laptops with lithium batteries, with doesn't really seem to make a difference if the battery is in or out while the laptop is running on AC. What does make a difference is how much you discharge the battery when running the laptop on battery power, and of course how many times it gets discharged.

Also I've read somewhere something that does seem to have a general agreement: lithium batteries do not respond well to being fully discharged, and they should be stored with about 40-50% power (not full!) and in cold environments.

In case it matters, both the HP Pavillion and the Packard Bell have Intel Core2Duo processors while the Asus has a P4 processor. the HP has an NVIDIA GPU, while the Packard Bell has an ATI and the Asus an Intel.