the cooling idea

[sideways]

i know we've all looked at a starter motor and drooled (a cheap powerfull motor!!) and then cryed because we know it will die if you use it for to long so what about the ways of cooling such a motor? you could make a water jacket for it really easyly i think, one piece of pipe that fits snugly over the motor then another much larger one over that with the ends sealed and some holes drilled for water to flow through, you could use a wiper washer pump to pump the water around and a heater core as a radiator! has anyone ever done this? if so how did it go? another option would be to weld lots of fins onto the snugly fitting pipe to make it air cooled.

 

[sideways]

another way of doing a water jacket could be to wrap copper tubing around the motor in a coil, much easyer but i dont think it would work as well as the other kind, probably more expensine too.

 

[mike75925]

heatsink? vent the case, and put mesh in the openings? the brushes are what normally cooks in electric motors, windings not so much. put an alternator style fan on it for forced air cooling with case vents front and rear. copper coil, has been covered. jacket with pump and radiator, covered. thinning the case, then jacketing? drill the armature shaft (maybe the vanes too), have coolant run through it, with a cooling jacket around the case? so many possibilities

 

[Kaptain Krunch]

Normally the armature not brushes.

 

[frederic]

Make a duct out of thin metal as a shroud, and install a huge fan at the end of the shroud. It works very well, as I myself have used automotive starters as a continuous duty motor without an issue.

The key is airflow.

Also make sure the starter you use has ball bearings rather than the older kind that has cruddy bronze bushings. In continuous duty applications those bronze bushings disappear very quickly.

 

[gilpna]

Make a duct out of thin metal as a shroud, and install a huge fan at the end of the shroud. It works very well, as I myself have used automotive starters as a continuous duty motor without an issue.

The key is airflow.

Also make sure the starter you use has ball bearings rather than the older kind that has cruddy bronze bushings. In continuous duty applications those bronze bushings disappear very quickly.

thank you, i will also attempt a starter motor go-kart in the near future and i will definitely take all this info into account

 

[Qmavam]

i know we've all looked at a starter motor and drooled (a cheap powerfull motor!!) and then cryed because we know it will die if you use it for to long so what about the ways of cooling such a motor?

Yea, but I've thought more about converting an alternator to a
motor. Some will work at 80 amps + and you can drive them with over 100 volts. That 10 hp, if it works!
I recently found this thread on an RC hobby group of some people doing it, and using already built hobby motor controllers.
(pretty serious motor controllers). Someone is even selling modified rotors with large rare earth magnets on them to eliminate the slip ring to the rotor.
It is a very long thread ya might want to start at page 12 or 13
and read through page 15, then read the rest of the thread. If you have no knowledge about alternators just start at the beginning.
http://www.rcgroups.com/forums/showthread.php?t=905411
Mike

 

[frederic]

An alternator is essentially a three-phase AC generator that's rectified to give reasonably smooth DC, and driving this with a three phase AC signal would make it spin.

This is a VERY good idea. Any speed controller for a 3-phase AC motor could in theory be scaled. I imagine the difficult part would be not driving the 3 phase windings, but the field current.

 

[Qmavam]

An alternator is essentially a three-phase AC generator that's rectified to give reasonably smooth DC, and driving this with a three phase AC signal would make it spin.

This is a VERY good idea. Any speed controller for a 3-phase AC motor could in theory be scaled. I imagine the difficult part would be not driving the 3 phase windings, but the field current.

The field current is not difficult, just 1 to 4 amps dc.
But the permanent magnet rotors even take care of that, and also from what is said, give the altermotor more power.
Mike

 

[frederic]

The total current produced by a 3-phase alternator is 1.73 x any one phase's current, and the reverse is also true: each phase of your alternator will need 144A to produce full output as a motor. Not what you were expecting, I bet ;-)

The PM rotors often take care of that however it's not a specific part of the design, but residual magnetic fields left over from operation as an alternator (with a driven field coil).

In other words, don't count on that magnetic field being there, and drive the field as you desire anyway. There is a general rule of thumb with field currents in automotive alternators - essentially it's a 1:30 ratio. So if you want to draw 60 amps out of an alternator that's capable, you'd need two amps in the field coil to get it.

Not sure how that would apply when using the alternator as a motor, but maybe it's a good starting point.

 

[Qmavam]

The total current produced by a 3-phase alternator is 1.73 x any one phase's current, and the reverse is also true: each phase of your alternator will need 144A to produce full output as a motor. Not what you were expecting, I bet ;-)

Not sure what it all means, but you should still get 80 to 90%
efficiency from the motor.

The PM rotors often take care of that however it's not a specific part of the design, but residual magnetic fields left over from operation as an alternator (with a driven field coil).

In other words, don't count on that magnetic field being there, and drive the field as you desire anyway. There is a general rule of thumb with field currents in automotive alternators - essentially it's a 1:30 ratio. So if you want to draw 60 amps out of an alternator that's capable, you'd need two amps in the field coil to get it.

Not sure how that would apply when using the alternator as a motor, but maybe it's a good starting point.

The thread I mentioned has grown a lot since I mentioned it, but I'm not really getting information that I could put to use.There seems to be a lot of bickering and many are looking for someone that can show a working motor.
Mike

 

[frederic]

I'm not really getting information that I could put to use.There seems to be a lot of bickering and many are looking for someone that can show a working motor

I think the number of people who run alternators as a motor are few and far between, so your hope for a working model to copy is at least somewhat unrealistic.

I don't see any bickering here, only discussion, discussion that can benefit you if you choose.

Since you obviously want just "the answer" and no more "bickering", I'll give you working schematics out of my collection and you can fire up your soldering iron and have at it.

Good luck.

 

[Qmavam]

I think the number of people who run alternators as a motor are few and far between, so your hope for a working model to copy is at least somewhat unrealistic.

I don't see any bickering here, only discussion, discussion that can benefit you if you choose.

Since you obviously want just "the answer" and no more "bickering",

I didn't say there was any bickering here, I said the the thread I mentioned had a lot of bickering in it. It now has 25 pages, out of the last 10, I think 5 are bickering.
This is the thread I mentioned.
http://www.rcgroups.com/forums/showthread.php?t=905411
Mike

 

[frederic]

Well then, it seems I misunderstood where you were referring to, and thought you meant here.

Since I am mistaken, please accept my apologies.

 

[bigfootrules31]

i have an even better idea, mount it inside a bucket of water.
the water will keep all the electrics inside nice and cool

 

[Qmavam]

Well then, it seems I misunderstood where you were referring to, and thought you meant here.

Since I am mistaken, please accept my apologies.

Not any problem at all frederic. I probably wasn't as clear in my reference as I should have been
Later, Mike