I don't understand electric motors!

Jmzvet

I read a lot of posts from people replacing 2.5HP stock motors with 8HP motors and not getting the results they expected.
That's like turning a 250HP gas engine into a 1000HP monster!
Am I wrong? (I probably am)!

BGW

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scottyb

It takes more than a motor. A motor cannot perform if it is starved for voltage and amperage.

55BigBlock

Scotty B is right. One of the first things you do to increase HP in a gasoline engine increase the amount of fuel with a modified fuel system. In a golf cart the fuel system output(batteries) is limited by the total output of the controller.

Jmzvet

Starting to make sense now

scottyb

There is a lot of upgrade info here > Scotty's upgrade suggestions
There are 2 types of drive systems; series and sepex (aka shunt) sepex is short for separately excited. Series wound and separately excited are 2 different electric motor designs. Both have their advantages. Series motors produce more torque and Sepex motors produce more speed.

Generally series cart upgrades increase torque with a little boost in speed and sepex upgrades boost speed with a little increase in torque. Owners can be disappointed if they are not informed. Often I hear I bought the neighbors old cart and I want to drive around town at 25 mph. Then we find out it is a series cart better suited to off the road use. There are exceptions, like the Club Car series motor MOT-A1 which makes both speed and torque.

The effect of voltage upon performance is often overlooked. The best performance will be on 48 volts. We still have a lot of members running on 36 volts complaining about performance. This is especially true of the series cart owners. These carts need a voltage upgrade.

To get the best results look at the system in total. Any component that is under rated is a pinch point in the delivery chain

JohnnieB

An electric motor or internal combustion engine is only one component in the drive system. It is proceeded by an energy deliver system and followed by the final drive ratio. For optimal performance, every component in the entire drive system has to be well matched to all the other components in the drive system.

Also, HP without being associated with a rpm or torque value, is a poor yardstick for comparisons.
For example: The same motor produces 2.5HP at 4300RPM and 8HP at 2200RPM and 15.25HP at 1000RPM.

scottyb

I concur. I recently went round and round with a guy who wanted to convert his street cart to an off road cart with bigger tires and controller/motor upgrade. Then I find the cart has hi speed gears. Tall gears just will not work for any off road set up. It is the summary of each component that makes the total performance.

The same gearing challenge applies to carts with seriously tall tires... tire size changes are gear ratio changes too. And they adversely effect power.

JohnnieB

Along that same line, a tall final drive ratio (Gears + Tire height), is the opposite of what is needed for off-road. If tall tires are needed for ground clearance or other reasons, the motor needs to have more torque to compensate for the torque loss caused by increasing tire height.


I see you added a comment about tire height while I was typing.

WalterM6

Sort of like putting in a 1000HP motor and not replacing the 1 barrel carburetor.