Replace Laptop battery in NZ Friendly, Reliable Professional Distributor!

What is the danger of charging the battery when plugged in all day?

That depends. Is your laptop new enough and smart enough to compensate for this? For example... a new Toshiba with the Eco Battery monitor running that won't charge the battery unless it drops below 80%? If your computer is like that... where it has a specific feature that will protect your battery when the unit is plugged in all the time.... then no it isn't harmful.

However, if your laptop is like the vast majority of laptops out there and in use, then you would be micro-charging the battery by leaving it plugged in all the time with the battery present. This would shorten the life of the battery by reducing the total number of charge cycles the batteries in the battery pack have available.

Without know the make and model of your laptop, it is hard to say.

So.... if you want to be on the safe side, charge your battery and remove it from the laptop when it is at 100%. Don't charge the battery again until the charge has dropped to about 25% to 30%.