Negative Voltage on Cart Frame

[simple man]

Your motor could have a partial short to the case. You will need to remove the cables from it and test each terminal to the case for resistance. Any low resistance reading would be your problem!
Make sure to disconnect the battery pack + and - cables, label your motor connections, and hold the nut under the cable ( nut nearest the motor ) so the stud doesn't turn while you're removing the motor cables.

[caokgafamily]

Simpleman is correct,
I had the same problem on my cart and It was the motor leaking juice going through the rear end through the leaf springs into the frame. My motor was just over worked for a long time, 25" tires with a 500amp FSIP will fry a bandit motor. I replaced the Bandit with a torque & speed motor and I get no readings on the frame. Amazingly the Bandit still works, I just stalled it out to many times in the woods.
Steve

[Stevegrmich]

Originally Posted by simple man

Your motor could have a partial short to the case. You will need to remove the cables from it and test each terminal to the case for resistance. Any low resistance reading would be your problem!
Make sure to disconnect the battery pack + and - cables, label your motor connections, and hold the nut under the cable ( nut nearest the motor ) so the stud doesn't turn while you're removing the motor cables.

. . . except he stated . . "While the batteries were removed I checked the frame and the negative voltage was still there."

. . .

[gornoman]

Yeah, back up the bus on this one. We need this statement clarified.

[simple man]

Originally Posted by Stevegrmich

. . . except he stated . . "While the batteries were removed I checked the frame and the negative voltage was still there."

. . .

Yeah, I missed that part too! I do know the controller capacitors will hold a charge for quite awhile. Could that be the voltage reading with no batteries installed?

[gornoman]

Originally Posted by simple man

Yeah, I missed that part too! I do know the controller capacitors will hold a charge for quite awhile. Could that be the voltage reading with no batteries installed?

Highly unlikely. I keep thinking we have a funny multimeter here. Or it's on the wrong dial setting, ohms perhaps?

[notsoquick]

I just replaced all 6 batteries, installed all new 2AWG cables from steveb. Great cables btw. Also recleaned the entire battery box and recoated with undercoating. Still have some power to the frame (9.5 volts) as compared to before, 40 volts. The other problem is the charger will not shut off. I have to manually unplug is when the battery pack gets to approximately 61 volts. Any thoughts on the charger issue?

[notsoquick]

My bad, the cables came from scottyb not steveb.

[Volt_Ampere]

As I said before, it only takes a little leakage anywhere to get some voltage between the battery negative and the frame. The meter is a very high impedance so it doesn't take much to make that happen. Try putting a 10K resistor across the meter leads when you make the measurement and I bet a beer that the voltage goes down to less than a volt.

[notsoquick]

Originally Posted by Volt_Ampere

As I said before, it only takes a little leakage anywhere to get some voltage between the battery negative and the frame. The meter is a very high impedance so it doesn't take much to make that happen. Try putting a 10K resistor across the meter leads when you make the measurement and I bet a beer that the voltage goes down to less than a volt.

Would a little leakage to the frame (9.5V) trick the OBC into thinking that the batteries haven't reached the charge limit?