Battery connected backwards

[KubotaSam]

I just bought my 3rd Kubota b7100. I seems like a great little tractor. I bought it from a dealer that took it in trade for a new Mahindra. Now here is my problem. I just got a chance to look it over at home today. I opened the hood and was looking it over when I noticed the battery cables were connected backwards. The cable to the starter solenoid was on the negative and the cable to the ground was on the positive. The tractor started and ran fine. I have only run it about 10 minutes since I got it. Here is what I am guessing happened.

1.Someone installed a totally dead battery backwards.
2. tried to start but battery dead.
3. boosted from a car or truck with the cables backwards on the tractor so it started.
4. The tractor charged the battery backwards so - is now +

I put a meter on the battery and the needle swings backwards. If I put the meter on - to + on the battery it reads 13.2 volts.

How do I fix this without buying a new battery? My idea is to put a load on the battery and drain it totally. Than try to charge it with the connections correct. What do you guys think? Has anyone ever been down this path? Seems I read about it but can't find anything.

[joshuabardwell]

Until just now, I had no idea you could reverse-charge a 12 volt battery this way. Other Internet forums say that it happens when the battery goes dead flat and then is charged backwards. Presumably, to fix it, you would run the battery dead flat and charge it forwards. But bear in mind that deep discharging automotive-style starter batteries is pretty bad for them. If it was me, I would consider just letting it continue to run backwards until it died.

[EE_Bota]

I would discharge, connect properly, then recharge with a desulfating charger. I have no compelling reason to do so.

In many batteries, the negative side and positive side are designed differently from each other to account for special physical conditions in that part of the battery. Whether that matters or not, I don't know, but I'd want correct terminals/colors/markings on my system regardless, so keeping the old battery is just the fun/educational part of the project...so I'd keep the old one, and write on it the date of the re-reversal just to see how I came out.

[Gary Fowler]

If it is working as is, just run it till it dies. Obviously it is working now and showing full charge.

[texasjohn]

weird... never heard of such a thing...guess it can happen because you have the case proving the point...I think I'd not fix it until it breaks.

[rayclar]

hard to believe, get a new or used charged battery , hook it up the proper way before you short out all the wiring alternator starter and what not. Its not designed to run that way???

[Hooked_on_HP]

I didn't know it was possible either. I would call the dealer I bought it from and see what his thoughts are. Aparently every thing is working ok but if it were mine I would want it right.
Bill

[Gale Hawkins]

If it is working as is, just run it till it dies. Obviously it is working now and showing full charge.

For sure.

I have done reversing polarity on 12 junk batteries trying to get them to desulfate. When I just reversed charged them until after off the charger overnight they would read ZERO volt then recharged correctly I had some success (not worth the time if you need a good battery). The ones that I got to hold a reversed charge and test so so died HARD when I try to reflip them to OEM polarity. I think the write up is on this forum somewhere.

Again I would just use it as is as long as it starts OK then get a new battery.

[Gale Hawkins]

hard to believe, get a new or used charged battery , hook it up the proper way before you short out all the wiring alternator starter and what not. Its not designed to run that way???

rayclar it is looked up properly. The polarity markings on the battery are just wrong now.

Until I wanted to buy a battery I would do NOTHING based on many hours of testing/experimenting with the process of reverse charging of lead acid batteries.

[puckgrinder85]

I would contact the dealer and see what they'll do. If nothing at least you'll have some leverage if something should go wrong down the road.