DIY Electric Car Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
163 Posts
Discussion Starter · #1 ·
it has 32 comm bars, 8.5" diam. and 17.5" long( pretty long.

here are some photos o the brushes and guts:




















 

·
Registered
Joined
·
163 Posts
Discussion Starter · #4 ·
ok thanks alot major :)

the reason i needed an answer right away is because the dump i got it from has another identical forklift with the same motor, and they only charged me 50$ and i got a 48v controller, some contactors and wiring.

i have another GE 11.5" 15.5" long motor, and it has 65 comm bars! isnt that alot??? does this mean i can feed it high voltage like 200v?
the odd thing is though that the 8.5" motor has huge brushes for its size, and the 11.5" acctually has its brushes a little smaller...

so what are the basic reasons why that motor would be good major?

is it because:

large brushes
large comm. bars count
large internal structure?

thanks
 

·
Registered
Joined
·
7,791 Posts
Is that 5min rating going to matter much?
Hi Wood,

That is the way (or a way) pump motors are rated. It is capable of running longer at reduced loads, maybe half of its 5 minute rating would be a one hour rating. But if it is a series wound motor, half rating would be quite a high RPM. So if you intend to run it at higher than nameplate voltage, too high RPM might be a problem.

The OP didn't say what the intended application is, just asked if it was a good motor ;)

Regards,

major
 

·
Registered
Joined
·
7,791 Posts
i have another GE 11.5" 15.5" long motor, and it has 65 comm bars! isnt that alot???
That is a fairly common bar count for these fork motors of that size.

does this mean i can feed it high voltage like 200v?
Hard to say.

the odd thing is though that the 8.5" motor has huge brushes for its size, and the 11.5" acctually has its brushes a little smaller...
Difference between pump and traction motor design.

so what are the basic reasons why that motor would be good major?
I can't list everything for you here. Read thru http://www.diyelectriccar.com/forums/showthread.php/using-forklift-motor-and-choosing-good-7598.html Like I told woodsmith, it looks like a good well built motor in decent shape. Whether it is right for your intended application is a different question. And I usually don't answer that particular question. Too many variables. You do best by reviewing what has worked for others with similar applications as yours.

Regards,

major
 

·
Registered
Joined
·
163 Posts
Discussion Starter · #7 ·
im planning to run the 8.5 on 144v probobly. on a 2200lbs 2 door vehicle with manual trans.
 

·
Registered
Joined
·
2,217 Posts
I think it will be fine with that, though you might want to limit the motor voltage a little (perhaps 120 peak volts) as the comm bar count is a little lower than ideal. The bar count as the same as my Prestolite MTC motor. The motor you've found is a bit larger overall so it should be fine in a 2200 lb. car.
 
G

·
Looks like a GE motor. Good motors. Stout and strong. The large of the motors you describe has a good com count. What are you putting it into.

Pete :)
 

·
Registered
Joined
·
163 Posts
Discussion Starter · #10 ·
the 8.5" is going into a saturn sc1( my dads converting his car too after i did mine)

and the 11.5" GE i want to put into either an older porche, an rx7, or something along those lines.

whats the effect of a motor that has been over volted? lets say i take my motor ( 8.5") and put it in the saturn with lets say 200v, how would it react? bad eficiency, heat?
 
G

·
I would not take it to those voltages. If you go up to lets say 120 or maybe even 144 volts then you need to be sure you have your motor advanced. If not you will have arcing problems with those high voltages. I am using a 9" GE with 96 volts and it works great. I will be moving to 120 volts here soon. My motor is neutral timed and I will not go higher with that motor. With my Kostov motor I would go to 156 volts since it can be advanced a great deal. It also has interpoles which helps.

Pete :)

I'd stick with 120 or 144 volts max for the smaller motor. The large one if advanced I'd go with maybe 144 volts. Motors get hot so you need to extract the heat. If you can keep it cool then your motor will live just fine in an over volt state.

Most are built with low voltages and are set so that they can run at these levels all day every day year in and year out and live just fine. You won't be driving your car for long periods of time like you might drive an electric forklift.
 

·
Administrator
Joined
·
6,276 Posts
Hi Guys

Voltages in series DC motors
- the way I understand it 10 - 20 volts will drive 1000amps through one of these

But you need your 10 - 20 v + the back EMF caused by the motor spinning

So for a given speed and current the motor voltage is going to be Back EMF + 10-20

If you don't increase the speed you can't increase the motor voltage

Therefore your battery voltage is irrelevant - except that a higher voltage will result in a lower battery current

Therefore you should use the highest voltage your controller can handle

Brush advance is also related to speed so the same thing

Have I got this right Major?
 

·
Registered
Joined
·
7,791 Posts
Hi Guys

Voltages in series DC motors
- the way I understand it 10 - 20 volts will drive 1000amps through one of these

But you need your 10 - 20 v + the back EMF caused by the motor spinning

So for a given speed and current the motor voltage is going to be Back EMF + 10-20

If you don't increase the speed you can't increase the motor voltage

Therefore your battery voltage is irrelevant - except that a higher voltage will result in a lower battery current

Therefore you should use the highest voltage your controller can handle

Brush advance is also related to speed so the same thing

Have I got this right Major?
Hi Dunc,

Not the way I would have said it, but I don't see anything blatantly incorrect with it :) Thanks for your help ;)

major
 
1 - 13 of 13 Posts
Top