I'm working on a project for college and I'm not having much luck finding suppliers for motors, they're either wrong voltage or too small. I'm considering a 0.8Kw starter motor as they seem to match everything else (And I think we should have a motor in this ranmge anyway, my tutor doesn't agree though and won't like it).

Would I be alright using a 24V motor on 12V and just having half the speed or will that cause me problems?

Only real restriction is it has to be available from a largish UK supplier and ideally around £100 but theres leeway on that.

Why not run the 24V motor on 24V? also what are you going to do or speed control?

Speak to City Belts and Bearings. They specialise in not only belts and bearings, but motors and drives too.

http://www.citybelts-catalogue.co.uk/browse_categories.aspx?level1=20001

If its not in their catalogue, then they can get it.

I would ask what duty cycle are you running the motor at.

Starter motors will not run continually for long periods without overheating, also you have the pinion gear to contend with that will need to be permanently engaged possibly!

I would ask if you could not use say one of the small child’s scooter motors or mobility motors although they will probably be 24 Volt or more.

If you need control then you would probably be going PWM control

Adrian

[Edited on 20-1-13 by AdrianH]

Crouzet do quite powerful D.C. motors but the prices will scare you away.

What about the brushless motors commonly used in aeromodelling? They come in a huge range of outputs and rpm/volt.

Thanks for the tips.
It has to be 12V for completely arbitary reasons, we looked at using two batteries in series to make 24 but it's not permitted.

The way things are looking it's going to end up woe fully underpowered, but it's not to big a deal as the finished product isn't what the project is about, it's just annoying though.

I get a new tutor in febuary so I might just humour the current one and swap to 24V when he's gone.

So 0.5hp is about 370Watts.

12v means that it will draw around 31Amps.

I don't see why you couldn't convert a car alternator into a motor (see for example http://www.youtube.com/watch?v=WBeyqX6OKlc). Most alternators can put out more than 30Amps, and run continuously, so can handle the duty cycle.

Matt

Car dynamo can be used as a motor and speed could be controled using a potentiometer on the field windings. Not sure about the power output though

Would have thought some of the more powerful 12V cordeess tools would be around that sort of power - my old dewalt cordless is 240W and that is not a heavy duty tool.

Does your project absolutely have to be 12v? You'll get rather lower switching and copper losses with a 24v setup (I^2R loss, twice the voltage, half the current, 1/4 of the losses).

Unfortunatly yes.

Do you have a budget for the motor

just did a quick google

This one is listed at £191 OMPMDC12-18-12V-56C 1/2 hp
or OMPMDC34-18-12V-56C 3/4 hp


LINK


Or as mentioned above
RC model Brushless motor
Seen them over 5KW.

For example this may give 500w on 12V
LINK
for less than £25.
Speed controller like this LINK
Then get a servo tester to drive the controller.


[Edited on 20/1/13 by rf900rush]

[Edited on 20/1/13 by rf900rush]

Thanks for the tips.