Tractor battery reversed

[Rodster]

Hi
My daughter's boyfriend asked me to take a look at his lawn tractor. He said all it does is click. After looking at it I put the meter on it thinking it had a bad connection or weak battery. I was getting -12 volt. The battery was reading backwards. He said he charged it but that the charger was hooked up correctly. I have never seen this happen before. The tractor is only 2years old.
Rodster :bonk:

[Rodster]

Any Ideas how this happned???
Rodster

[Carl]

The charger was hooked up reverse polarity. There is no other way that the battery charge can reverse.

[chipmaker]

I have never seen or even heard of a typical lead acid battery reversing polarity. It is however quite common on nickel cadmium if they are not maintained correctly.

My youngin installed a battery in my 180 Deere backwards, and the starter worked, but the starter motor ran backwards....

[mla2ofus]

I saw an instance yrs ago where a friends LT batt went completely dead and he hooked the charger up wrong and it charged up fully but the starter spun backwards. So I'm guessing a batt will charge with reverse polarity if it is totally dead. If there's any charge in it, I'd think the circuit breaker in the charger will trip.
Mike

[chipmaker]

I still do not think its possible to change the polarity on a lead acid battery due to the nature of how electrons flow.........that part is a given.......but I am still doing som e checking as it has my interest......first I have to go pickup 11 more treadmills and some other associated exercise equipment...............the salvage saga never ends.....

[Carl]

The active elements in a lead acid battery are the electrolite (sulfuric acid) the positive plate (lead oxide), and the negative plate (lead sulphate).

A university site that I found has a physics experiment for lead acid batteries. The positive plate is formed by charging the battery.

Another site that I found says that by completely discharging a battery it is possible to reverse the charge by reversing the polarity of the charger. It talks about one or some of the cells will reverse. (carrying this to the extreme then if totally dead then can reverse all the cells).

From this information then the battery, if completely dead, can have the polarity reversed. Only the physical construction of the positive and negative plates is different so the battery will not be as powerful or robust in the reverse charge state. It will destroy the battery.

[Rodster]

Hi
thats what has me puzzled. it was reading 12 volts. The lights were bright, The starter solonoid made a strong click but the starter would not spin. I took the cable off the starter and turned the key taking a reading off the cable. Thats when I noticed the (-) in front of my digital meter. I took that battery out of the tractor and used a battery that read the correct polarity and it worked perfect.
Rodster

[aguysmiley]

I used to work at a marina. As we winterized boats, we removed the batteries on any of them that we stored for the customer. These batteries were marked with the customer's name and stored on shelves. During the winter we would charge and test two batteries a day, one in the morning and one in the afternoon. The batteries were all supposed to be marked on the positive side of the battery, and then set on the shelf with the name facing outwards. This way there should have been no confusion. There was one battery that wasn't marked properly and therefore sat on the shelf with the negative side facing out. It didn't get caught and the charger was hooked up to it backwards. After charging, it had reversed the polarity of the battery. It also killed the battery. The tester would show 12 volts without a load, and would drop to 1 or 2 volts under load. You had to connect the tester backwards to get a reading. Connecting it the way it was supposed to go made the needle peg below zero.