[JohnnieB]

Sounds like a bad connection (excessive resistance) in the charging circuit. Someplace between the heatsink the diodes are on and the transformer center-tap inside the charger and the main + and - terminals on the battery pack inside the cart.

Your dash mounted DVM is connected between the battery pack's main + and - terminals, but the charger's control board is looking at the voltage between the heatsink and center-tap. Excessive resistance in the wires/cables connecting those points will cause a higher voltage to be seen at the control board than at the battery pack when there is amp flow in the charging circuit.

Clean all the connections and the problem might go away.

The charger is likely to be working normally, just seeing artificially high voltage.

Attached is a TC-III manual.