motor identification help

[dcastillo]

Im always keeping my eye out for motors on the cheap and found a guy on craigslist with a few including a MY1020 750W (he says) that I might put in my daughter gokart (replacing her 500W)
He also has two unmarked motor and no clue what they are.
one has a short toothed gear that probably cant be used, but the other appears to have a keyed shaft that looks very usable.
he says they are about 7" long (not including shaft)
Does anyone have any idea what these are and how much power they might have? Would love to replace the 35yr old golfcart motor Im using now.
Thanx
Danny

 

[itsid]

we're facing a "length of string" situation here...

both of these can either be hallf the power of the my1020 or tripple the power of it... or anything in between... well even beyond
both can be wound for 12V or 72V

you can ask the seller to measure the internal resistance to make an assumption..
the lower the resistance, the more likely it's a lower voltage DC motor
and by guessing the voltage, you can sort of calculate the powerdraw from that alone
(and with another assumption on the efficiency you could guess the power out)
but it's still nothing but an assumption, and chances are you guessed wrong on the way...
Frankly, those need to be thoroughly tested to tell what power they have and what Voltage they like best.

So yeah.. how long is that piece of string now?!

'sid

 

[dcastillo]

HAHA, nice answer without answering (that is a very good skill to have mastered)

So worse case, they are 12/24V motors, I put 36V (what my cart is setup for) and I end up burning them up...
Is there any danger to the driver when the burn? I just want to be sure to keep safety in mind as I have never had a motor failure before...
Currently I have a 100A fuse inline with the motor, so that shoudl prevent any fires from wires over heating...
Maybe I should make a lowball offer just as an experiment, might get lucky and have a decent motor
What would be a reasonable price for the unknown motor... thinking Ill tell him $25 bucks?
Also, would the weight in any way give an estimate on the power or not really.

Also, my cart currently has 6 batteries, I could rewire them as 24V at 57AHrs if the motors seems to like that more..

thanx again Sid
Danny

 

[itsid]

Well Danny.. what can I say;

well these are likely to be industrial motors... something like a 46 frame or something (cannot find a table for the specs on different frame sizes atm)
Anyways, those sizes aren't going to tell you anything at all;
yes, sure a more powerfull motor likely need a larger frame; but still
a common frame size nowadays is 56 for example.. and motors in that framesize range from as little as 300W to as high as 4kW or so.
So there goes that.

Weight is not only caused by the windings (although that's indeed a major cause for weight)
but the rotor core also adds to the weight, so does the shaft...
so a five star core is likely lighter than a seven star core..
And even worse...number of windings and gauge of the wire can result in the same overall weight for two very differently setup coils.

And if it couldn't get worse some hosusings are beefier than others and therefor heavier when stripped down.
No, I don't think weight can give you an idea what you're looking at at all.

Sorry, but if you don't have a testbench equipped with some flukes and a good lab powersupply (settable 12-72DC and some amp limiting)
it's likely a waste of time and money.

If I had to make a guess, it'd be the seller either KNOWS what power they have and is hiding that info away for a reason, or he bught them out of curiosity and figured they're not up for his task (too low on power)
or worse.. he already fried them whilst testing.

'sid

 

[dcastillo]

Thanx, I have the equipment, but at work and probably not a good idea to take it outside with me
Will definitely check out his other MY1020 motors and possibly get those for future kid projects and see if he will throw in the bigger one..

supposedly he picked up a bunch of things (including GC controllers) from a guy whos dad tinkered with electric projects but passed away and the son didnt care for any of it. So he says anyways.

thanx
Danny