# Generator/motor conversion question



## Georgia Tech (Dec 5, 2008)

NCMau said:


> Hi Folks, I am back with a new question. I can't believe how informative this forum is. Being new in the EV area, I will start getting involved in a moderate fashion by building a slow speed cart for the grandkids ...and me. I already have a sturdy lawnmower frame with hydrostatic transmission and a 400A Curtis controller. So what I need is a motor. There are plenty options on ebay, but I am hoping to use what I have on hand.
> My question is this: I have a 28VDC, 100A military surplus generator. This is a heavy machine. I hooked up 12V to it, just to see if it rotates. It locks up, drawing a bunch of current (of course was just a brief test).
> Has anyone ever used or has knowledge if this type of generator can be used as a motor?. If it can, it would be an ideal motor size for my project. If it can't, I guess I have to bite the bullet and buy a golf cart type motor.


 
I have had a couple of these things my self. they can be some what confusing if you don't know what to look at. First off which of these motors do you have? You could have had the GE version or the Jack and Henzs version. With these two versions you could have had the pure generator type or the Starter Generator version. At first I thought the Starter Generator was the better type, but I found the starter series version to be some what ineffecient and vertually useless. So really I consider these motors as shunt motors.

Now The real question is how you have it hooked up. How many large terminals do you have and how many small terminals do you have? When you say you put power to it and it loocked up what specificly do you mean? Do you mean that the shaft rotated freely and when you put the juice to it, it locks up? Or do you mean it just does not turn and when you put the juice to it. Give me more details and I can help with it..


----------



## NCMau (Jan 27, 2009)

Thanks for the reply.
This is not a starter/generator like Jack and Henzs. This is a pure generator that is usually installed in a jeep-like vehicle to operate a load such as a radio communication system. Military comm systems often use 28VDC.

There are 3 prongs out of the generator. The plug that connects to the generator has two leads marked positive and negative. The third lead is a small wire that has male and female straight plugs connected to each other. 
The shaft rotates freely before applying voltage.When I applied the 12V battery the generator does not spin and does not rotates freely. It acts just like an AC motor with defective start windings with exception that it will not rotate if you manually spin it. During the short test, I was not able to measure the current but I could tell it was excessive.

I really don't have much hope to use this generator as a motor, but it is worth a try to pose a question to people that are more knowledgeable than I am. You never know, and again, thanks for the interest.


----------



## Georgia Tech (Dec 5, 2008)

NCMau said:


> Thanks for the reply.
> This is not a starter/generator like Jack and Henzs. This is a pure generator that is usually installed in a jeep-like vehicle to operate a load such as a radio communication system. Military comm systems often use 28VDC.
> 
> There are 3 prongs out of the generator. The plug that connects to the generator has two leads marked positive and negative. The third lead is a small wire that has male and female straight plugs connected to each other.
> ...


Sounds like your activating the field without puting any current to the armature some how. Does it draw lots of current like a short?
Can you post photos?


----------

