Easy 12 or 24 v generator

[pistnbroke]

Spotted this on canal world discussion forum www.canalworld.net its a small 4 stroke driving a three phase model motor...What the writer does not say is that the voltage is regulated by the engine rpm so a governed 4 stroke run to give 14.4 or 28.8v makes a compact generator . Look in Equipment under DIY 12v generator ..at present its on the first page ( 4/march/11)
for those who dont know the whole of the motor body rotates only the ali bit with the slots at the bottom stays stationary and the second number on the label gives the revs per volt in this case 230 but other specs available...google hobbyking this motor max 37v .motor power 3200w 4 HP thats 80A and 8500 rpm...... Enjoy

[kbowen]

Be VERY careful if this is going in a confined space. Real boat generators and starters are totally enclosed to be "explosion proof." This doesn't mean they will never explode, it means that if gas vapor gets inside and gets ignited by commutator sparks, the case of the motor is strong enough to contain the blast. Also, If that 3 phase motor is a "re-purposed" model airplane motor, it is used to getting a lot of ventilation.

[CatBuilder]

Wouldn't it be much better to have a smart, 3 stage charger circuit dictating the RPMs so that you have a real battery charging ability, plus an engine that kicks up the throttle when demand increases?

[kbowen]

Originally Posted by CatBuilder

Wouldn't it be much better to have a smart, 3 stage charger circuit dictating the RPMs so that you have a real battery charging ability, plus an engine that kicks up the throttle when demand increases?

There is no reason you couldn't belt a regular marine generator to a small gas engine, Lawn mower or outboard that lost it's lower unit, etc, etc. Lawn mowers usually have a crude governor on them. I once needed a battery charger and had a junk car generator and spare 1/2 hp electric motor from a washing machine laying around. I bolted the two to a 2x12 and put a belt between them. I could switch the contacts between 6v or 12v voltage regulators to charge either, and I also experimented with a rheostat on the field windings and could get 30 amps out of the thing. It was prevented from overheating because it was in Minnesota during winter, which is why I needed a battery charger in the first place :-) Beware that if you use an alternator rather than an old-style generator, disconnecting the battery while the thing is charging can fry the diodes &/or voltage regulator.

[pistnbroke]

I posted it out of interest......no commutator so no sparks and I think the guy uses it outside his canal boat . very little space insde for airflow and the coils are stationary not spinning...if its rated at 80A then pulling 10A and sealing it should be ok subject to test ....The regulator would need to be a MOSFET in series or 3 in the three phase rectifier. just thought many of your techns would like to keep up to speed

[kbowen]

Originally Posted by pistnbroke

I posted it out of interest......no commutator so no sparks and I think the guy uses it outside his canal boat . very little space insde for airflow and the coils are stationary not spinning...if its rated at 80A then pulling 10A and sealing it should be ok subject to test ....The regulator would need to be a MOSFET in series or 3 in the three phase rectifier. just thought many of your techns would like to keep up to speed

Very cool technology. However I look at that thing in proportion to the guy's hand and look at the wires coming out of it and I can't help but wonder what parameters they used to rate it at 80 amps? The wires can't be more than 10 or 12AWG in the American measure, which would certainly carry 10A without much loss, but I expect it would start to show significant voltage drop above 40 amps or so.