Battery Voltage presented between Controller and Battery

[aditya369007]

We have a Club Car Precedent Exel I2 2011 model and recently replaced the controller unit believing that it was damaged due to sparking when connecting the batteries to the unit. With the newly replaced unit, and everything properly wired, there is still a voltage of 47 volts between the negative terminal of battery six and the wire going to the unit.

Assuming that there is a short in the wiring we checked all of the wires going into the controller unit and there was a blown 15 Amp fuse. We replaced it but the problem persisted.

What could be the problem? Can anyone help us out?

Thank you in advance.

[Gazoo]

How old are the batteries? Maybe a weak pack?

[aditya369007]

The batteries are new and with full voltage. I have checked that

[Raystar57]

If I am reading this correctly it seems there is a "open" in a crimp in that cable.
If it were good you should not read much voltage drop across it. So near 0 volts.
Replace that cable and see.
Some medium sparking at cable hookup is generated by the capacitors in the controller charging.

[Sergio]

It sounds like the pack negative cable is disconnected and the voltmeter is being used to complete the connection, in this case the voltage would be near pack voltage due to the meter high-impedance.

I have never seen just the Controller produce much of a spark since the 470Ω pre-charge resistor will limit the initial in-rush current to less than 0.1 amps.

The capacitors on most voltage converters will definitely produce a spark since those capacitors charge current is not limited.

Perhaps aditya369007 can clarify how the measurement was taken (where meter probes were placed).

[Raystar57]

Thanks Sergio, agreed.

[aditya369007]

The measurement was taken between the black wire that's coming out of the obc and the negative terminal of the battery 6.
The probes were attached between these two places.

Originally Posted by Sergio

It sounds like the pack negative cable is disconnected and the voltmeter is being used to complete the connection, in this case the voltage would be near pack voltage due to the meter high-impedance.

I have never seen just the Controller produce much of a spark since the 470Ω pre-charge resistor will limit the initial in-rush current to less than 0.1 amps.

The capacitors on most voltage converters will definitely produce a spark since those capacitors charge current is not limited.

Perhaps aditya369007 can clarify how the measurement was taken (where meter probes were placed).

[Sergio]

Pack positive is battery #1.

Pack negative is battery #6.

The 10ga output wire coming off the OBC should be directly crimped with the negative cable (6 ga) coming OFF the battery #6 at the Controller B-.

There is also a 10ga input wire on the OBC (before the SCR) that goes to the charger receptacle, do not take readings on that wire.

Is that not the way your cart is wired?

[aditya369007]

The golf cart is exactly wired in this form.

Originally Posted by Sergio

Pack positive is battery #1.

Pack negative is battery #6.

The 10ga output wire coming off the OBC should be directly crimped with the negative cable (6 ga) coming OFF the battery #6 at the Controller B-.

There is also a 10ga input wire on the OBC (before the SCR) that goes to the charger receptacle, do not take readings on that wire.

Is that not the way your cart is wired?

[Raystar57]

It would seem that the negative cable crimps are bad in that cable.
Could be at the battery end or at the Controller B- as Sergio stated.

First I would replace the crimped end at the battery first.
If needed replace the other crimp at the Controller B-.