Running a 1/4 - 1/2 hp electric off 12 volt car/golf cart battery

[bearboom]

Hi,
Newby here trying to design a small piece of lawn equipment in my shop. I want to design my own leaf blower using a small electric motor to turn the shaft of a squirrel cage blower. A friend of mine built himself this same system except he used an old lawnmower motor. It works great but I wanted to try an electric motor, instead, to avoid the noise and pollution. Naturally, my next thought was to power it with a 12 volt battery so I'm not dragging a cord around. I have no idea of the type and size motor I would need, if it would work fine with one 12 battery or if it would need several. If I understand correctly, there are 12 volt DC motors I could use so I don't have to buy a converter but I have several electric motors in my shop and I'm trying to do this as inexpensively as I can. My original idea was to have 2 batterys, one being used on the cart and one charging so I can swap out when the first battery runs low. This machine would probably not be used continuously for more than 2 hours at the most and the squirrel cage fan is not extremely large(it measures ~16"x18"x6" wide). I had planned to run an ordinary fan belt from the blower shaft to the motor shaft. Let me know how feasible or how "stupid" this idea is and the basics of how it could be set up.
Thanks.

 

[chroot]

You should start by telling us the specifications of the electric motors that you have on hand.

- Warren

 

[vk6kro]

Remembering your question, I had a look at a $60 leaf blower at a local hardware store.

It was 2400 watts at 240 volts. The speed of rotation was not given, but it sounded like 4000 to 5000 RPM. Amazing power.

Any motor you had would need to be a series wound universal motor to match that speed of rotation. Look for RPM on the motors. If it says 1800 RPM, it is probably a squirrel cage motor out of an old washing machine. Such a motor would not be suitable.

But there is the problem of running it off 12 volts. Suppose your motor was only 500 watts, that is still 42 amps but it would have to come from an inverter that gave 120 volts out. These are efficient but not perfect, so the current would be even higher. I imagine such inverters would cost more than a commercial leaf blower, but I haven't checked.

I think I'd put up with the power cable and get one that runs off the mains or get a gasoline powered leaf blower.

Home Depot have electric blowers for $70
http://www.homedepot.com/h_d1/N-5yc1vZ1xgl/R-100530552/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053
(235 MPH!)

Actually they have a cheaper one for $30
http://www.homedepot.com/h_d1/N-5yc1vZ1xgl/R-100615513/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053
(That one is only 150 MPH!)

or gas ones for $169