[major]

Originally Posted by alvin

Just what is it that makes them rated for only 20% internally?

Nothing, the same motor will also have a 100% rating. Just that the 100% rating will be a smaller number than the 20% rating.

It is the application which determines the DC, not the motor. However if the motor designer knows the application DC requirements, there are some things he may choose to do differently inside the motor. Brushes come to mind. They usually heat up faster at high currents. So a 20% DC motor designed for such may have larger brushes or even a longer commutator than a similar motor in 100% rated applications.

major

[jackbauer]

quick question about my compound motor. Didnt want to start another thread. If i'm running it from a pwm controller with a seperate supply for the shunt windings , would i be in danger of something nasty when i lift off the pedal with the shunt winding still energised? ie would the armature try and generate and fight with the series winding etc? Ultimatly i want to use this setup for regen but that won't be for a while.

[Woodsmith]

Here are some photos.

Top view.


The drive motor is only 8" diameter.





The pump motor is 8.5" diameter.







What was 'scary' looking at the truck was that there was no cover over the battery pack and a long handled spanner was sitting on top of the cells between the terminals!

[major]

Originally Posted by jackbauer

If i'm running it from a pwm controller with a seperate supply for the shunt windings , would i be in danger of something nasty when i lift off the pedal with the shunt winding still energised? ie would the armature try and generate and fight with the series winding etc?

Hi jack,

I don't see a problem like that. It'd be similar to running a PM motor with PWM. A lot of guys do that with no issues. And a few guys, like Mike, have used those aircraft starter/generators in set-ups like this with no reported problems.

Regards,

major

[Woodsmith]

Originally Posted by major

Hi jack,

I don't see a problem like that. It'd be similar to running a PM motor with PWM. A lot of guys do that with no issues. And a few guys, like Mike, have used those aircraft starter/generators in set-ups like this with no reported problems.

Regards,

major

I guess the other issue would only be current consumption generating a field in the shunt coils for no reason. How about a high pedal cut off so that there is no wasted energy when not energising the controller?

[jackbauer]

Thanks Major just wanted to be sure. woodsmith i will have a micro switch on the throttle body so it kills the shunt field at zero throttle was just worried! That forklift looks great. Get it

[Woodsmith]

Originally Posted by jackbauer

That forklift looks great. Get it

Great for you or for me?

I was thinking the drive motor was a bit small and the pump motor will only have a female shaft.

Could I still run either motor at 120-160 volts and achieve 70mph (4200 rpm) for 30 minutes?

I was really looking for an 11" motor to give me that high speed cruising ability without over loading the motor or drawing too many amps.

[jackbauer]

Great for me of course just kidding. Would probably be more suited to a smaller vehicle in a less demanding application but i still would get it to have "in stock" for future as its so cheap and so near.

[Woodsmith]

Originally Posted by jackbauer

Great for me of course just kidding. Would probably be more suited to a smaller vehicle in a less demanding application but i still would get it to have "in stock" for future as its so cheap and so near.

Just to have in stock? I'm not made of money.

Seriously though, is my thinking correct in looking for an 11" over, say, an 8" or 9" motor for high speed cruising?




I have just bought this pair of motors from Ebay to make something small from. Thinking of a compact tractor.....

[electromet]

Wood,

I noted that you expressed an interest in a 13" motor the other day, and I just want to make sure that you've checked all the appropriate clearances to the transaxle case & driveshafts from the cenerline of the motor shaft. It would be a shame to find out the darn thing doesn't fit alongside the MR2 mechanicals. Maybe you should make a cardboard motor mock-up?

Mike