On Tue, 30 Oct 2007 03:19:30 -0700, wrote:

NoSpam wrote:

I've just decided the old petrol rotary is too rusted to repair again
and, while doing some research into a replacement, have stumbled over
cordless mowers.
I'm naturally cynical about claims but the Bosch Rotak specs claim
they're OK for 400m2 of lawn on a single charge, and the Lithium-ion
batteries should last well (if they don't burst into flames :-( ) - but
has anyone actually used one? Are they any good?

Dave

Smallest petrol engined mowers I've seen have been 2hp, which is
1.5kW.
To get 1.5kW for 1 hour at 12v would require 125A and 125Ah - or
allowing 25% for fast discharge, 156Ah. IRL they'll be higher than
12v, but thats to give an easy comparison to batteries we're all
familiar with.

IOW something has to give, with real life power output being lower
than the lowest available petrol mower.

Also a large set of batteris and charger costs a lot more than a
mains lead, so again you're getting a lot less mower for the
equivalent cost.


NT
Had a sealed lead-acid battery powered mower a few years ago - one of
the "better" makes. ( One of the brands owned by Bosch)

Was impressed with how much grass it did cut on a charge, but
batteries no good after 2 seasons and the official replacements -
non-standard size were about £100.
I managed to use a standard size but it still works out expensive.

The advantages for me was the stop start facility of an electric mower
without using 100m + of extension cable and the low noise level
compared with a petrol powered one.


It kept falling to pieces and I couldnt be bothered to fault find the
pcb when it stopped working as I was about to move.

Batteries are very heavy as well.
Robert