? Reversed Polarity on Battery?

[Cushman UTV Max]

I have just picked up a 90's Cushman 48 Volt UTV Max cart.

Prev owner said it worked fine last year, dead this spring.

I am told an "uncle" worked on it for 3 hours, with no luck.

I trailered it home, and checked the water level in the batteries. All okay

The battery pack voltage was around 24 volts.

2 batteries had near zero voltage

1 battery has reverse polarity with -6.4 volts.

Anyone seen reverse polarity? Why does it happen? I am ready to pull it, and find another. Anyone think there is an alternative?

The other two batteries with near zero voltage seem to be taking a good long slow charge.

I am going wire by wire, terminal by terminal to clean all connections, and look for damage/cause.

I have found one wire grounding out to the chassis. It was connected to one of the dead batteries.

I am using vaseline to coat the terminals once clean.

All advice welcome. Tony in Michigan.

[scottyb]

A direct short will kill a battery and even those connected to it....Sounds like you need batteries, they never come back from 0 volts to healthy batteries again, in my experience. Sounds like you are going at this in the correct mannor...Good luck

p.s.
A SG specific gravity test with a hydrometer or a load test will tell the story.

[Cushman UTV Max]

I do appreciate good advice. The batteries that measured just under six should come back, right? The two zero batteries seem to be taking a charge. Am I wasting my time fooling with them? I will look for a hydrometer and post the results. Thanks, Tony. By the way, any advice on where to get good terminals? All I seem to come up with are cheap, weak, and did I say cheap...

[WickedCarts]

we have had reverse voltage .. wire a light to the one battery and let it drain.. lights dont know + - charge once it is a zero then cart it.. we have seen thes on alot of NEV (gem or think carts)

[Cushman UTV Max]

So, I take it that I can drain the one battery that is reversed in polarity, I can run it to zero, and then charge it back from zero with the correct polarity. Do I have it correct? Will the battery be descent enough after this treatment? Thanks, Tony

[WickedCarts]

yes you have that right.... if the battery was good before then it will be ok now.... but if the battery is old then maybe not.. reverse polarity doesnt make the battery bad

[Cushman UTV Max]

Okay, wonderful. I have a light on it now, and letting it run overnight. I have two chargers, one 2 amp, and one 10 amp. I am alternating them around the group of 8 batteries. Pulling them up bit by bit. I will pickup a hydrometer, and see where all the cells are. Thanks for the input. Tony

[WickedCarts]

no Im Randy