Driving home and the "check guages light" lights up and the voltmeter drops to zero. Truck continues to run and drive fine all the way home. I get home and pop the hood to find the passenger side battery spewing acid. Drivers side battery looks fine with the green light and no venting. I shut the truck off and restart. The voltmeter starts working again but is pulled down to 10-12 volts like the grid heater is running which is possible at 59F. Did the alternator die or did I just lose a battery?

 

Did you disconnect the bad battery before restarting?

 

No. The truck started right up.

 

I would get that battery out of the truck. Then see what happens with the voltage after that. I would think the battery could be pulling down your voltage.

 

you will need a multimeter to trouble shoot

get rid of both batts if your not sure how to trouble shoot if you got good batts or bad batts.

If one of the batts are shorted you could be asking for trouble running the engine. The bad batt can take out the good batt.

 

Thanks for the info. Both batteries are coming out in the AM and being replaced with Duralast Gold group 65. I washed down the bad battery and the surrounding area to dilute the acid that spewed out.

 

I know a little about this actually. When a battery is bad the plates inside it become sulfated and will make the battery swell up when it gets charged. Chances are the alternator was charging it and it eventually went under the pressure.

reasons for this can range but basically if a battery is jumped too many times or isn't maintained it can do this.

Maintenance free batteries are convenient for this reason because you don't ever need to add water to them.

 

I check alternators on tractors by starting them and removing the negative terminals. If the tractor keeps running then the alternator is working and if it shuts off then the alternator is bad. Just the other day I changed my batteries because my truck wouldn't start even though the little green lights were visible. After I replaced them the truck started up just fine.

 

This is NOT a good practice. Much better and simple ways to trouble shoot alternators then this!

 

That is no longer a Valid test..............on newer vehicles the voltage spikes that can be produced will be expensive.
The green lights in batts are just a hydometer,but it is only on one cell,again not a valid test.

Bob

 

Replaced both batteries with Duralast Gold group 65 (875CCA, 1000CA). Voltmeter is back to normal. New batteries are not venting and appear to be charging correctly.