755 Compact Tractor Battery is inflating like a balloon.

[AZalace]

I have a 755 compact utility tractor. I was working with it a couple weeks ago, and when I stopped for the day I noticed a slight hissing sound under the hood once the engine was turned off. I opened the engine cover to discover the hissing was coming from the battery. It appeared to be inflated and there was some acid bubbling around the top seam. Fearing the battery might blow I immediately detached the negative cable and closed the engine cover. I let the tractor sit over night before I went back out to inspect. The next day the battery had returned to its normal size, but there was acid pooled in the battery tray. I took the battery out, cleaned all the acid up, and then drove to the local automotive shop to get another battery. I automatically assumed this one was shot and that I probably had a bad regulator in the alternator. The auto shop tested the battery and said that it was still good and tested out fine. I went back home and re-installed the battery. I then put a volt meter on the battery while the tractor was running to see if the regulator had gone bad allowing the alternator to pump too much current back to the battery causing it to inflate and leak acid. The meter read 11-12 volts while the tractor was idling, and never went over 14-15 when the tractor was under heavy load or driving. I have been told the alternator should never send more than 16 volts back to the battery.
I am lost at this point. What could be causing the battery to inflate like this? Is it just a bad battery, or should I pull the alternator and regulator and have them tested to make sure they aren't on their way out? Has anyone heard of or seen this before?

 

[Bird]

What kind of battery? Is it a normal (old style) 12 volt with 6 caps for adding water or is it a sealed battery? Caps on the old style were vented and if the vents were plugged you could get some inflation. I'm surprised you didn't have to buy a new battery.

 

[BobRip]

That sure sounds like over charging from the battery symptoms. I had a regulator on an alternator erratically fail and charge to too high a voltage. It seemed to do this after the engine ran for awhile (more than 30 minutes). Watch the battery voltage with the engine running at operating RPMs. If the voltage climbs after it warms up that is probably the problem. You should not have above 14.5 once the engine has warmed up. More like 13.8 to 14.2.

 

[Ron JD670]

When I read your post I thought both regulator and plugged vents. Unlikely the alternator. I would pull the regulator and have it tested or even replace it if not to costly and not integrated with the alternator. Did you test the voltage under full load - all lights on ?

I also would be very concerned about the mechanical integrity of the battery. I might be inclined to put it in a marine battery inclosure especially if you don't find a specific cause. So if it happens again the damage is contained.

Did you do anything to neutralize the acid from the battery? You might want to see if it sprayed anything under the hood. Acid can attach Aluminum, zinc, and copper very quickly and aggressively. Also any connectors near by should be checked.

Good luck
RoN

 

[jenkinsph]

I would not reinstall a bomb I mean battery that had swollen up as you said regardless of what the tests showed. The damage caused by leaks or explosion is far more costly than the battery.

I agree that it sounds like overcharging too and would monitor it closely to determine what the problem is/was initially.

 

[JD 4520]

When I read your post I thought both regulator and plugged vents. Unlikely the alternator. I would pull the regulator and have it tested or even replace it if not to costly and not integrated with the alternator. Did you test the voltage under full load - all lights on ?

I also would be very concerned about the mechanical integrity of the battery. I might be inclined to put it in a marine battery inclosure especially if you don't find a specific cause. So if it happens again the damage is contained.

Did you do anything to neutralize the acid from the battery? You might want to see if it sprayed anything under the hood. Acid can attach Aluminum, zinc, and copper very quickly and aggressively. Also any connectors near by should be checked.

Good luck
RoN

I agree with Ron and would replace the battery in addition to checking all other potential electrical relationships. The test performed by the auto store may or may not have been performed properly. A voltage test will not tell you much in a situation like this. Need to know how it charges, about the acid, about the amperage and other characteristics. Good like on the diagnosis but for sure buy yourself a new battery.

 

[jonyyuma]

Check your charging components, Last time I had a battery swelling it was the diode bridge was blown. It is over charging the battery..

 

[smalltown]

I agree with jenkinsph, and JD 4520 I would think twice about reinstalling that battery. Sure does sound like overcharging.

 

[YesDeere]

Agreed. That battery must go. It could be an internal short that only shows while being charged while running. Due to heat or vibration

 

[AZalace]

Thank you for all the speedy replies.
Bird the battery is an Exide 60 premium with two plastic caps on top covering the six openings. I am going to replace the battery, but how would you unclog clogged vents? I am assuming you simply pop the caps off and clean them?
Bob thank you for the info on your situation. I checked the tractor under numerous circumstances and under full load, but I did not run it for very long because I was concerned that I could do more damage running it before I figured out what is going on. I never thought about the regulator failing after an extended period of use.
Ron I did neutralize the acid that came out. I used a battery cleaner spray designed to neutralize acid. Some had made it out of the tray and down onto some of the engine components. Fortunately I got to it before the acid did anything more than remove paint. You guys aren't kidding when you said the acid can do damage and quickly. As for the regulator, it looks like the regulator is integrated into the alternator on this tractor.
For everyone recommending that I replace the battery, this will be my first course of action. From there I am going to run the tractor under full load for an extended period of time watching both the battery and the voltage going to the battery. If the voltage stays consistent under full load even after an extended period of time I will probably pull the alternator and take it in to be tested.
Has anyone ever taken an alternator apart to replace the regulator? I am just curious if this is something that I want to get in to. I have done a lot on this tractor thus far. I rebuilt the power steering column, rebuilt the front axle and spindle assemblies, and replaced numerous hydraulic lines running through the center of the tractor so I feel confident that I can rebuild the alternator/regulator unless someone knows of an aspect that I am not aware of?

Thank you again for all the help!

Arix