what causes a battery to smoke during a load test?

[The motor guy]

I load tested a battery of mine and almost instantly a cloud of smoke came from the battery. It stopped as soon as I unhooked the tester. What happened? Is my battery done for now? Do you think maybe the water could have been low when I tested it? I've never had this happen before so now I don't know what to do. I don't know if the battery could blow up randomly now or if it's fine.

 

[440Magnum]

Where did the smoke come from? One cell? Near a terminal?

The only thing I can think of is that its got a high internal resistance somewhere, probably from a failing cell that "reversed" during the load test. I suppose it could be low electrolyte levels, so check it. A specific gravity meter will tell you for sure if a cell is shot, but I would venture to guess that the battery should be replaced anyway.

 

[ahoier]

Can't say I've "seen" any batteries physically "blow up" - but have heard of the casing "expanding" with heat.....

How does the casing look...? Did it balloon at all?

Almost thinking the water/electrolyte was low......I typically check the water level on all my batteries before testing them....

And I top off each cell with distilled if it's low (I can not see the water in the cell).

 

[Chris142]

I'd say the battery is shorted internally. I've had 2 blow up here at the shop. One in the parking lot (hood shut)and one at my coolant flushing station.

The one at the coolant flushing station almost got me! I had just turned around to go get a tool when the whole top of it blew up and sent acid everywhere.

 

[The motor guy]

I'm not really sure where to smoke came from exactly. This is in a boat so the battery is in a compartment. I'm wondering if maybe the clamps touched each other and I didn't realize it. I bought a new carbon pile tester to replace my old cheese grate type. So I went to try it out. I already new the battery was weak. But I keep the both of them on a charger that charges both independently. I think for safety purposes I'm going to just replace it. I'm afraid to plug the charger back in now. I was hoping to wait until spring to put new ones on but oh well. I've managed to squeeze an extra 1.5 years out of these with the onboard charger I bought. My engine only requires like 360cca to start so even if the battery is worn out it still starts fine since most deep cycle batteries start out at like 600cca. Maybe I should just return the load tester I bought. I'm not sure i'll have enough guts to ever load test another battery again. That was scary. Just replace every 4 years needed or not.

 

[meep]

smoke from a battery is BAD. there is a lot of energy in them, even weak ones. if clamps touched there would be audible "crack" and visible damage. If you use a load tester, I think safety glasses would be important.

Marine batts typically aren't sealed... but if they are frozen they can still explode. Sealed batts usually have a psi relief... 2 or 6 psi... I can't remember which but those numbers stick out.

a hydrometer might be a safer way to test. marine compartments can be pretty tight... don't want to be too intimate with a questionable battery when it's under a hefty load or charge.

M

 

[SteveSRT8]

I spent time in the emergency room having bits of battery case picked out of my eyes after an explosion!

I'd be very cautious. This testing under extreme loads generates a ton of hydrogen gas very quickly.

Can you say "BOOM"?

 

[JHZR2]

Internal short and reversal. Batteries do explode and lead acid will go into thermal runaway under charge.

 

[The motor guy]

alright well I replaced both of those batteries. They were 4 years old anyways. Looks like I didn't get the negative clamp on all the way. I couldn't really see the post when I was attaching it but from the looks of the marks. I may have only had one half of the clamp on the post. I think that caused it. I think the clamp started to get hot on the post and dig into it slightly. How dumb of me huh. I think i'm gonna return the load tester. I didn't realize load testing was so dangerous.

 

[morris]

you cats are the smartest. this old man would love to be half as smart as you cats.

 

[JHZR2]

Originally Posted By: motor_oil_madman
alright well I replaced both of those batteries. They were 4 years old anyways. Looks like I didn't get the negative clamp on all the way. I couldn't really see the post when I was attaching it but from the looks of the marks. I may have only had one half of the clamp on the post. I think that caused it. I think the clamp started to get hot on the post and dig into it slightly. How dumb of me huh. I think i'm gonna return the load tester. I didn't realize load testing was so dangerous.


arcing can vaporize metal, though I doubt at that voltage. It would be a high resistance connection and could get hot...

 

[dishdude]

I had a battery in a van at work blow the vent cap off and have acid land on the exhaust manifold. It stunk so bad I could literally smell it across a large parking lot.

 

[edhackett]

Arc welding is done at low voltage. Most electrodes run at 20V. An automotive battery will deliver plenty of amps to pit metal.

Ed

 

[Garak]

Originally Posted By: SteveSRT8
I spent time in the emergency room having bits of battery case picked out of my eyes after an explosion!

I'd be very cautious. This testing under extreme loads generates a ton of hydrogen gas very quickly.


Agreed. In all my years of fleet management, I never got onto the load testing bandwagon. I've done it a few times, but, particularly when running a fleet and a vehicle actually out and running is required from a business standpoint, I found that if the battery is questionable, replace it. Piddling around with it for half an hour is forgone revenue, and an explosion and injury if something is done incorrectly are not worth it.

 

[meep]

I melted a pair of scissors at work with a 7amp, 12v UPS battery. it's not the volts that matters so much, but the amps....

Those big HUGE spotlights they use in arenas that using a motor-fed carbon arc for a light source? 36V.... the gap is around 1/4"

(loved working with those things... they were called "super troopers" back then...

M

 

[CBR.worm]

I had a battery explode right after I turned my back on it once. I was jump starting a car and was not as aware as I should have been that the jump battery had been charging and had a cloud of hydrogen over it. Luckily I connected the dead battery last and the bad connection arc was behind me.

I also had a battery explode out of the grill of my old GMC truck when I hit the starter after sitting for a few minutes. Must have been a marginal connection that arc'd

 

[The motor guy]

The one battery that was smoking smelled like rotten eggs when I pulled it out to replace it so it was bad for sure. Not sure if that's because it was old or because maybe I shorted it out. The other one didn't smell at all. I'm glad I decided to replace it and not put it back on the charger.

 

[kc8adu]

that one had a dead cell.
the 5 good ones in series with it charged it in reverse when you tested.the tester is safe.a bad battery may have an internal bad connection that creates a spark.its rare but if the right mix of hydrogen and oxygen exists in there kaboom!

 

[The motor guy]

So if I would have put my multi meter to it before testing I would have noticed the the battery would have been short by 2.1 volts correct? Which would put it at 10.5v completely dead.

 

[Garak]

Originally Posted By: motor_oil_madman
So if I would have put my multi meter to it before testing I would have noticed the the battery would have been short by 2.1 volts correct? Which would put it at 10.5v completely dead.


Something like that. In any event, that was pretty much how it was dealt with in my fleet usage. Test the voltage - if bad, replace it. Set the removed battery aside, try a slow charge, and see what happens. If it can't hold a charge, which would very likely be the case (and was virtually each time in my experience), it was kept out of use. If it were fine, well, time to check into the vehicle's charging system.