Random wrote:
As the subject says, has anyone here had any experience of the
following grass trimmer?

My old chum Ron used to say, in a wonderful aberdeen accent "That which is
cheap is generally very nasty".

I've used a lot of tools with these rechargable batteries, and been
dissapointed in every single one of them. Mains powered drills are hundreds
of times better than battery drills, electric screwdrivers run out far too
quickly and are heavy and clumsy. The number of recharge cycles is not very
good: ususally they put a thermistor in the battery and stop charging when
it reaches a certain temperature. That might make the charger cheap and
simple, but it seems to boil the batteries very quickly.

Based on all that, I'd be surprised if something normally based on a small
internal combustion engine could be usefully made round battery drill
technology.