My Sister in law has an Atco petrol lawn mower with battery start (turn key to start). After 12 years the battery has finally died and a replacement is about £50!

The battery is 12volt 2.5Ah and I'm wondering whether it can be replaced with a similar, or higher rating burglar alarm battery at about £10. The physical size and connectors will be different but I can easily modify them and make it fit. Is there any reason I've not thought of why this shouldn't work? Incidentally the mower has a pull cord but she can't use it because of a bad back.

I'd be grateful for comments.

No reason why you cannot use a different battery.

Current draw on battery might be only limitation as starter will require a substantial current for a few seconds and it might take quite a while for the battery to recover.

Dyno /starter may either try and overcharge battery or be slow in charging it.

this should do OK ......if it fits

Something like this should be more than OK....if it fits

Brand new YUASA NP7-12 battery 12v 7ah CHEAP No Reserve on eBay, also Other Rechargeable Batteries, Rechargeable Batteries, Batteries Battery Chargers, Consumer Electronics (end time 20-Feb-08 05:59:29 GMT)

It's not often appreciated that batteries have different charge/drain cycles.

A burglar alarm battery is designed to supply a smallis drain for a long time. A lawnmower (like motorcycle and car) battery is primarily designed to deal with the heavy short-term drain of running a starter motor.

So basically it looks like a good idea, but won't work in practice because it will kill the burglar alarm battery in nothing flat.

It's not often appreciated that batteries have different charge/drain cycles.

A burglar alarm battery is designed to supply a smallis drain for a long time. A lawnmower (like motorcycle and car) battery is primarily designed to deal with the heavy short-term drain of running a starter motor.

So basically it looks like a good idea, but won't work in practice because it will kill the burglar alarm battery in nothing flat.

Ken's right. The alarm battery will fail very quickly for that reason.

Visit a battery specialist for advice.

My advice is to fit another motorcycle battery, since that's almost certainly what the dead one is!

Agree with Ken. A motor cycle battery would be the righ thing to get, and you could get down to £10 or so if size/connectors dont matter. Here's just an example:

12v 4AH BATTERY SUITS ATV DIRT BIKE PIT BIKE QUAD DR on eBay, also, Trike, ATV Quad Parts, Motorcycle Parts Accessories, Cars, Parts Vehicles (end time 19-Feb-08 19:30:00 GMT)

Thanks very much for all the comments. A motorbike battery would seem to have been the answer. Unfortunately my sister in law went off this afternoon and bought a battery from a lawn mower rip-off specialist paying £53!

Well, it's her money.................