Also toying with 48V

I came into a “cheap” 48V motor that was probably for forklift duty or similar and I AM GOING TO put it in a VW KG (like, what, 1300#?). The motor came with no documentation and has no build plate… does anyone know a way to figure out who made it???
Also, it only has two posts. This means it is “series wound” or something else?
Typical for me, I will be doing this on the cheap (first one is a learner, right?) so I’ll likely use a reclaimed cart controller and five 12V bateries (4 for motive force, one for lights, etc.).
Do cart controllers have the 25mph limiter built in?
Then there is the issue with the output shaft… 1/2" with 9-splines… also about 1" long with no provision for a set screw/nut/whathaveyou.
I hear that using extra batteries (like 72V or more) is possible with the controllers that can handle such voltage because they “chop” the signal so the motor really only gets an average lower voltage with the advantage being you can “turbo boost” for short periods at a higher interval.
Does anyone “overdrive” their motors in this manner?
Is this something a motor like mine cannot do due to the lack of separate field inputs?
I am of the mind to just wing it but even at 48V the investment isn’t “free.”

Thanking everyone in advance for any input,


Hi Mike, Perhaps you can post a clear photo of your motor, It may help to identify it, Eric

Mike -
If I were to guess, sight unseen, I’d say you have either a permanent magnet DC motor (most likely) or an AC induction motor (less likely). There are other possibilities, but I think these two are most likely.

In my humble experience, cart controllers don’t have a speed limit programmed in so much as a limit on how much power they will deliver. A lot of golf carts get pretty abused - just search YouTube for stupid golf cart tricks. So, to protect the equipment, the controller may be programmed for a more gentle acceleration curve and perhaps other limits on output power.

I’ve got a couple of electric gokarts I put together. In both cases, I overdrive the motor as much as I can. My second kart originally had a Perm PMG-132 motor - this is a permanent magnet motor made to be a “one-up” on the Etek. Well, the Perm burned up after less than 8 hours of use. IMHO, it’s just not a very well built motor, and I’ve talked to others who have had failures just like mine. I replaced the Perm with a D&D series wound motor, and haven’t had a spot of trouble with it. I run it at 72v, and I run it hard. By the time the motor gets just too hot to touch comfortably, the batteries have run down, so in that way, my system is kind of “self protecting”.

From what I can tell, overdriving the snot out of electric motors is very common in electric karting and racing. It probably goes back to the fact that electric motors are generally rated for continuous horsepower, rather than peak, as are gas motors in cars. A 4 hp electric motor can deliver 20 hp in 10-15 second bursts easily. Just don’t expect to do that 24-7.

Probably the best “seat of the pants” indicator of what is too much for the motor is to monitor the heat. If it never gets too hot for you to lay your hand on it and keep it there for 20 seconds, then you’re probably quite alright. More than that and you’d better check into the motor’s specifications.

My $.02 worth.