controller Marathon Slow F & R full charge

[firefighter1138]

I have a 1992 marathon in reverse wont hardly pull itself forward seems slow I have full volatge (38.4V) at all points measured. Changed entire pot box same results. If i Remove half speed wire from micro switch reverse does pull cart but still acts like batteries are dead. Forward is always only like 75% of power that it was 2 weeks ago. any help would be appreciated. Thank You!!!

[yurtle]

Connect a digital multimeter (DMM) to the pack and try monitoring voltage drop while driving. If it drops excessively, you can do the same for each battery. You may have one bad battery that drops excessively under load.

[Sir Nuke]

OR you could have a bad F&R contact

[firefighter1138]

I did voltage drop and it was equal to another cart same year that works fine. Took F & R Switch apart was in good shape cleaned greased and put back together no change. Took motor out, ok ended up taking rear end out to get motor unstuck from spline. If it helps anyone, took old tire and installed on drivers side and stood rear end up on the end that tire was mounted on and picked it up about 2 feet and dropped it on cement floor 2 times and it popped off. Be prepared fro it to hit ground. I padded ground with cardboard boxes. Brushes are on order they were over half gone so hopefully this will fix it if not I will be going to controller, unless someone has better idea. Thanks for the tips that has been submitted.

[jericho]

Louisville KY. has a iron man contest every year where they lift 400lb tires.You may want to look into it.

[scottyb]

Originally Posted by jericho

Louisville KY. has a iron man contest every year where they lift 400lb tires.You may want to look into it.

LOL
I've done this on the edge of the concrete driveway where the motor falls onto the grass - it works well

[yurtle]

Originally Posted by firefighter1138

I did voltage drop and it was equal to another cart same year that works fine. Took F & R Switch apart was in good shape cleaned greased and put back together no change. Took motor out, ok ended up taking rear end out to get motor unstuck from spline. If it helps anyone, took old tire and installed on drivers side and stood rear end up on the end that tire was mounted on and picked it up about 2 feet and dropped it on cement floor 2 times and it popped off. Be prepared fro it to hit ground. I padded ground with cardboard boxes. Brushes are on order they were over half gone so hopefully this will fix it if not I will be going to controller, unless someone has better idea. Thanks for the tips that has been submitted.

Half worn brushes won't account for what you described. The springs should keep them snug against the commutator until they're nearly gone. You can clean the commutator with a scotchbrite pad.

[JohnnieB]

Originally Posted by firefighter1138

.............
Brushes are on order they were over half gone so hopefully this will fix it if not I will be going to controller, unless someone has better idea.
..............

If the brushes don't fix it, there are some voltage checks that will narrow the problem down to:
1. Bad high current cables or connections.
2. Bad controller.
3. Bad throttle input to controller.
4. Bad battery pack.

Jack rear wheels off ground and put on jackstands so half ton cart doesn't run over somebody or something.

Connect DVM test leads between B- and M- terminals on controller.
When pedal is pressed just far enough to make solenoid click, you should read FULL battery pack voltage.
If you don't, you have high current cable/connection issues.
If you do get it, press pedal to floor, voltage should drop to zero, or near zero.
(Don't let the motor free-rev too long, it isn't good for them. )

If it doesn't drop to zero, pull the Black and White wires (Throttle input) wires off the controller and connect an Ohmmeter between the wires.
Pedal up should be about zero Ohms.
Pedal down should be about 5,000 Ohms.
(I knew you said you installed a new pot box, but it may need adjustment.)

If the drive system passes those tests, it may be failing under load, so put it back on the ground and measure some voltages while driving it.

First, measure and record how far the back voltage drops while driving on level ground at wide open throttle.

Then connect your DVM between the M- and B+ terminals on controller.
When at full throttle on level ground, you should have the same voltage (or very near it) as you had at the battery pack when at full throttle on level ground.

Let us know what you find.