[Growster...]

Can these be left 'on charge', or should they be taken out once fully charged?

I have two, one for a Bosch strimmer, and another for a Bosch hedge trimmer, neither of which are being used at the moment of course!

[8doubles]

I believe that you will not damage the battery but it does affect the charger.
Most voltage drops on these chargers is achieved by losing the surplus power as heat. Even though the battery is full the charger will be costing you money.


Ps Li ion batterys can be topped up at any time without charge memory affecting them.

[grendel]

I believe Li ion batteries store best at about 40% charged-
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Grendel

[DD.]

Leaving Li ion batteries on charge will reduce their life. This is why, if you run a laptop at home from the mains constantly, you should remove the battery.

As per grendel, best stored at 40-50% of capacity.

[Annen]

My Black&Decker strimmer instructions recommend that the battery is left on charge all the time, and I find that I have to top it up before using it if I don't, as it doesn't seem to hold the charge for long. But I take it off charge during the winter and keep it in a frost free place.