EZGO 36V electric cart slow uphill

[Poser]

My manual shows 4 brushes. Could two be forward and two reverse?

[JohnnieB]

All four brushes are used in both forward and reverse. The are four field windings (two pairs) forming two stationary magnetic fields that are at 90° from each other. The four brushes connect to two sets of armature windings forming two rotating magnetic fields that are also at 90° from each other. In other words, there are effectively two motors turning the same output shaft.

The difference in forward and reverse is the direction the current travels in the field windings relative to the direction it travels in the armature windings. For example: When A1 & S1 are connected to B+ while A2 & S2 are connected to B-, the armature turns CW and when A1 & S2 are connected to B+ while A2 & S1 are connected to B-, the armature turns CCW.

All the High-Current cables used for forward as also used for reverse. All 13 cables are used for either direction.

Half-speed reverse not withstanding (separate and unrelated function), the only difference Forward and reverse is which cables are connected together by the contacts on the cam in the F/R switch.

The fact that you measure 30V between M- and B+ in forward and 21V in reverse, can only means the is a bad connection between the movable contacts on the cam in the F/R switch and the stationary contacts the cables are connected to. Since it is a new F/R switch assembly, I suspect the problem is mechanical.

Is the cam fully rotating to the mechanical stops in both forward and reverse?

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This is a separate issue that I see. You are only getting 30V between M- and B+. When the pedal is on the floor, the voltage between M- and B+ ought to be equal to the battery pack voltage at the time. More correctly, with the pedal on the floor the voltage between M- and B+ terminals on the controller ought to equal the voltage between the B- and B+ terminal on the controller.

Unless the battery pack voltage is actually dropping to 30V when the pedal is on the floor, you have some bad High-Current cables, connections or contacts.

[Poser]

Originally Posted by JohnnieB

Is the cam fully rotating to the mechanical stops in both forward and reverse?

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This is a separate issue that I see. You are only getting 30V between M- and B+. When the pedal is on the floor, the voltage between M- and B+ ought to be equal to the battery pack voltage at the time. More correctly, with the pedal on the floor the voltage between M- and B+ terminals on the controller ought to equal the voltage between the B- and B+ terminal on the controller.

Unless the battery pack voltage is actually dropping to 30V when the pedal is on the floor, you have some bad High-Current cables, connections or contacts.

The cams on both the old and the new F/R switch rotate all the way. The battery voltage at the terminals reads 35 when the pedal is depressed all the way but never reaches the motor. Only about 30 in reverse and 21 in forward. (M- to B+ reading while moving with the pedal floored).

The connections at the F/R switch are now new and clean. I guess I'll disconnect, clean, and replace the other ends and see what happens.

[JohnnieB]

Originally Posted by Poser

1. The cams on both the old and the new F/R switch rotate all the way.

2. The battery voltage at the terminals reads 35 when the pedal is depressed all the way but never reaches the motor.

3. Only about 30 in reverse and 21 in forward. (M- to B+ reading while moving with the pedal floored).

4. The connections at the F/R switch are now new and clean. I guess I'll disconnect, clean, and replace the other ends and see what happens.

1. & 3. There is a difference in how much voltage gets to the motor in forward and in reverse, so there has to be a voltage drop in the F/R switch contacts.
Measure from A to D while going forward and then measure for B to C while going forward.
Next, measure from A to B while going in reverse and then measure for C to D while going in reverse.

2. 35V into the controller, but only 30V out means the throttle isn't telling the controller to go to 100% output (ITS circuit issues), or the controller is bad.

4.