Cordless lawn mowers - any good?

Oct 29, 2007 14 Replies

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


The question isn't what's the capacity now, it's what will the capacity be in two years time...

Ben

Not used one, but is there any reason to suggest they would be any better than a mains powered electric mower? If not then stick to petrol!

Does it say what the charge time is?If you only manage to cut half the lawn (Think first cut of the season which may well be a bit long, or when you've missed the right length cos of a holiday) then you'll struggle to get it charged and cut again the same day.

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

Dave, No idea how good these are but I can buy them at discount. I've mislaid your email addy but you can contact me at bobdotminchinatntlworlddotcom and I'll send you the staff prices.

Bob

Talking about the Li-ion batteries, how do these hold/deliver charge in cold weather? I've noticed that the batteries for my camera (also Li-ion) last a matter of minutes when I'm using the camera at night during the winter. Now I appreciate that you (probably :-) won't be cutting your grass at night, but the chemistry in the cells does reduce their capacity when they're cold. So you may find that you'll get less grass-cutting capability in the early morning if your mower's been kept in a cold shed overnight.

Lion would be a pretty expensive technology for a high power battery. Output falls with lead acids too of course, at sub zero.

NT

Hold is good, deliver is less good. But probably good enough. They are far more like lead acid in their general feel and behaviour than nickel base cells

That is probably poor cells that simply sag under load when cold: the capacity should not be affected. Ive seen cells that run past limits appear to do just that, but if left for a few minutes, the voltage comes up and they will deliver full capacity.

Now I appreciate that you (probably :-) won't be cutting

May be expensive but being used more and more - Latest electric outboard motor uses Lion instead of Lead Acid.

One of the claims is that Lion can be repeatedly fully discharged without ill effects unlike Lead ACid. Thus a Lion battery with half the capacity can be used.

Isnt one of the latest hybrid drive cars using Lion ? Robert

May not be your cup of tea but you could get a scythe. A lot less pollution than a mower. Cheaper to run and service Good exercise =A339 in p&p from

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I used a scythe for 2 summers as a teenager - only injuries were splinters from the less than perfect handle. :)

Long handled ones are unwieldier, but can cut much more per stroke. However, is a scythe going to be up to cutting through all the woody bits?

NT

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