Battery lawnmowers

Sterlingtimes

The less green lawnmowers are always specified by power, e.g. horsepower, Watts) but battery lawnmowers are specified by the voltage of the battery. We might think that a 40-volt lawnmower is twice the power of a 20-volt lawnmower. What is the typical power range of a battery lawnmower?

QrizB

Good question, and I wonder why that is?

The Spear and Jackson 34cm 40V cordless rotary lawnmower (as seen at Argos) has a 36V, 2.5Ah battery. That's 90 watt-hours. It claims to cut for "up to 40 minutes" so that would suggest a 135 watt motor. (It's probably a bit more than that as you won't be using all the power, all the time.)

I suspect marketing decided not to mention this as it would make it look underpowered when compared to a 1000W mains one. Whether that's an issue in practice would come down to lots of other factors.

Martyn1981

I was looking at these recently, and Screwifx has a good range, though I found the Mountfield models a bit cheaper elsewhere. Some makes give areas for each mower as a guide to what to buy. But, I like to mow once a week so I can leave the collector off, and go at a brisk pace, then job over, whereas a two week mow will mean dogs/cats bringing in grass, so you have to collect it, and the (mains) mower goes slower as the motor works harder cutting longer grass, so 'area' might be misleading depending on how frequently you mow. I suppose the solution is to get one with two batts, so you can charge one, whilst working the other, just like cordless drills.

Sterlingtimes

QrizB said:

Good question, and I wonder why that is?

The Spear and Jackson 34cm 40V cordless rotary lawnmower (as seen at Argos) has a 36V, 2.5Ah battery. That's 90 watt-hours. It claims to cut for "up to 40 minutes" so that would suggest a 135 watt motor. (It's probably a bit more than that as you won't be using all the power, all the time.)

I suspect marketing decided not to mention this as it would make it look underpowered when compared to a 1000W mains one. Whether that's an issue in practice would come down to lots of other factors.

Thank you for following a mathematical approach. Your answer makes sense to me. So it appears that the motor power is quite tiny. For me, I think that the 230-volt approach will serve me better.

ABrass

Robot lawnmowers are the future. It used to take an hour to mow mine each week, now it doesn't.

Silvertabby

ABrass said:

Robot lawnmowers are the future. It used to take an hour to mow mine each week, now it doesn't.

Unless they have vastly improved recently, robot mowers don't cut the grass - they just randomly nibble at it. 

ABrass

Silvertabby said:

ABrass said:

Robot lawnmowers are the future. It used to take an hour to mow mine each week, now it doesn't.

Unless they have vastly improved recently, robot mowers don't cut the grass - they just randomly nibble at it. 

It doesn't matter what colour the cat is as long as it catches mice.

michaels

Our 2AHr 24v 33cm will do our 35' x 85' lawn (about 250m2) on one charge if it is shortish and dry, needs at least 2 and possibly 3 charges if it is long and wet.  Luckily it came with 2 batteries so we can do it it one go.

NigeWick

Sterlingtimes said:

 What is the typical power range of a battery lawnmower?

I've got a Bosch Rotak 40. If the grass is reasonably short & dry, it will easily do 200 square metres. If the grass is a little longer & damp, it will just about manage our back lawn which is 120ish square metres.

michaels

NigeWick said:

Sterlingtimes said:

 What is the typical power range of a battery lawnmower?

I've got a Bosch Rotak 40. If the grass is reasonably short & dry, it will easily do 200 square metres. If the grass is a little longer & damp, it will just about manage our back lawn which is 120ish square metres.

Google suggests there are different battery sizes available, but based on our experience it sounds like you may have the 2AHr one?

NigeWick

michaels said:

NigeWick said:

Sterlingtimes said:

 What is the typical power range of a battery lawnmower?

I've got a Bosch Rotak 40. If the grass is reasonably short & dry, it will easily do 200 square metres. If the grass is a little longer & damp, it will just about manage our back lawn which is 120ish square metres.

Google suggests there are different battery sizes available, but based on our experience it sounds like you may have the 2AHr one?

No idea, I just bought the cheapest  could find with two batteries. Plan A was one for the back and one for the front lawns. Plan B is that, when the grass is dry,  I can do both mine and my 91 year old neighbour's front lawn before the second battery runs out,