Marathon is faster in reverse

[plantguy90]

well, got good batteries, and it still dogs on small inclines. about 3-4mph on 4%. Odd part is its slightly faster in reverse. What could be the problem and is it possible to switch something so the reverse speed can be used to go forward?

[twp5253]

Sounds like the F/R switch might be tired? I am assuming you have one...I could be wrong. I only own a Txt Series cart but the Forward part of my old switch was toast and it worked better in reverse before I made these minor mods!

[JohnnieB]

Originally Posted by plantguy90

well, got good batteries, and it still dogs on small inclines. about 3-4mph on 4%. Odd part is its slightly faster in reverse. What could be the problem and is it possible to switch something so the reverse speed can be used to go forward?

Reverse the A1 & A2 cables at the motor.

Be sure to use two wrenches and hold lower part of stud so it doesn't turn or you'll break the wires going to the brushes.

[plantguy90]

EDIT: Sorry I am getting 38v at the controller, not 18, so wiring up to there is ok.

If I want to check the voltage to the motor running forwards (rear tires are in the air) which ones do I do hit touch S1, S2, A1 or A2?

[JohnnieB]

Originally Posted by plantguy90

...........If I want to check the voltage to the motor running forwards (rear tires are in the air) which ones do I do hit touch S1, S2, A1 or A2?

Here is a generic diagram showing the hi current circuits only.
I don't believe your cart has a fuse in the hi-current circuit, but everything else is probably the same.
Without all the interlocks, keyswitches, buzzers, control circuits and charger connections cluttering up the picture, it is easier to see what is going on.



The output to the motor can be measured between B+ and M- on the controller.
Being a series motor, the same current that passes through the armature (A1-A2) also passes through the stator (S1-S2).
Electrically, the only difference between Forward and Reverse is the direction the current flows through the stator, so the speed should be the same in either direction.
Physically, the current passes through different contacts on the F/R switch, so there could be a difference in speed/torque if the resistance of one set of contacts on the F/R switch was greater than the other.

The output of the controller is pulsed DC (PWM @ ~18KHz), but you might be able to see a difference in the DC voltage measured with a DVM across the stator (S1-S2) in Forward and Reverse.

Personally, I would clean or replace the contacts in the F/R switch, or replace the entire switch assembly with a heavy duty one.