# Overvolting Golf Cart Motor



## major (Apr 4, 2008)

adamj12b said:


> I am looking into replacing the batteries with 12V ones to increase the voltage to 72V. ......... Do you think it would stay together at 96V? .........


Hi Adam,

I'd say you'd be seriously close if not over the RPM which would damage the motor. And I would worry about vehicle stability at higher than design speeds. And can the brakes handle the higher speeds? Higher weight?

I know, you don't want to hear all that 

major


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## Sunking (Aug 10, 2009)

I have modified a few EZ-GO series carts, and you can easily go from 36 to 48 volt with no problems; , but you want to go from 36 to 96?


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## adamj12b (May 4, 2009)

Hey Guys, 

Thanks for the response's. Another question I have, What is the usual RPM limit of a golf cart motor? This one is an old GE motor that appears to have bearings at both ends. 

I would believe the brakes could handle the higher speeds, but im hoping to add disk brakes to it if its going to be upgraded that high. As for the weight, The current cargo rating is just under 800 LBS. It could easily handle the extra 160lbs from 2-80lb batteries.

The reason I am asking about all of this is im working on converting this golf cart to an LSV(Low Speed Vehicle). I've looked up the laws in my state (MA) and found out that I will be able to drive on roads marked 30 MPH and lower, at a speed limit of 25 MPH. What I need to be able to do this is add a windshield, Directional's, Brake Lights and Seat Belts. I don't need to add headlights because it already has those. 

Currently, the fastest Ive gotten it to go is 20 MPH, and thats was on level ground, with a full charge and about 1/3 mile to get to that speed. But, even at that speed it is very stable. 

What about 72V?

-Adam


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## major (Apr 4, 2008)

adamj12b said:


> What is the usual RPM limit of a golf cart motor?


Hi Adam,

Not sure, but I think in the normal application they run up to about 4000 RPM. Some courses have hills and down hill they can go like 50% faster. This overspeed would result in some commutator failures. This was one motivation to move to SepEx motors and controllers in golf carts so the downhill speed could be limited with regeneration.

If yours is an older cart, it most likely has a series motor. The motor RPM is proportional to voltage. So going to 48 volts can result in a 33% faster top speed, depending on the vehicle load. But you can see all of that downhill or if a wheel is lifted. 72 volts could double motor RPM.

I cannot tell you an absolute RPM limit for the motor. These are smaller than the big EV motors so might stand higher RPM. But they are also made cheaply. I would not be surprised to see it come apart at 8000. Maybe if the comm was built on a Monday, destruction at 7000. 

The other thing you may have trouble with is motor heat. Golf carts use totally enclosed motors. You increase voltage, increase speed, you'll increase load. Result is more motor loss and more motor heat. Add more batteries, it can run longer. More heat. 

But what the H? Kill a motor or two. It can be fun 

major


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## Sunking (Aug 10, 2009)

Ok you are in my area of experience. There is no set RPM for golf cart motors. They range from 3200 to 7200 RPM. It depends on if you are looking for torque for things like hunting, hill climbing, and speed for racing and NEV. You cannot have both.

You do not have to go to 96 volts to get 30 mph, 48 volts will get the job done, I know I have a golf cart that goes 30 MPH.

There are a lot of places to buy the equipment to do this, allow me to make a suggestion. Well what kind of cart are we talking about first?

For an EX-GO fleet series motor you will need to change out the 6 Trojan T-105 6 volt batteries with 6 Trojan T 875 8 volt batteries. Replace all the #6 AWG cable to at least #4 AWG. Replace F/R switch and relay to a heavy duty to handle the extra current and voltage. Replace the stock controller with a minimum 400 amp altrax, and then replace the motor with a GE D398 Raptor motor. That will get to to about 28 to 29 MPG. To go 30 you will need a lift kit and larger tires

FWIW there is a forum dedicated to modifying golf carts called Buggies Gone Wild. There are some folks there that have 70 MPH golf carts, and those boys use 60 and 72 VDC with special motors.


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## adamj12b (May 4, 2009)

Hey Sunking,

The cart is a Columbia Par Car. its about 20 years old, but in great shape for its age. I am already planing on adding some larger tires to it, as well as new suspension for a better ride. That mono leaf spring in the front does wonders..... Also, The controller that I built for it is easily capable of 500A and can be turned up to 775. Ive only been able to peak the golf cart at 300A and that was just flooring it on the road. As for wires, Its in the works as we speak. I got about 100 feet of 4 AWG fine strand wire from a friend for free. Im working on making up all the new connections over the next 2 weeks. 

30 MPH would be good, But im hoping to be able to maintain 30, even up small hills.

-Adam


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