After serious thinking Martin Brown wrote :
You can expect to do 15 minutes hard work with it every 2 hours or so.
For me a mains powered one wins hands down every time provided that you are
disciplined about where the trailing flex goes and have mains.

Here, that would involve around 4 or 5 recharges, so a 10 hour day
cutting, instead of the couple of hours work at present, we don't
really have that much hedge.