REALLY hot battery, what would you do/have done?

[Just_sayin']

Just had a bit of a nightmare. Totally my fault but hoping to learn from it.

I have a 220ah service battery that I rarely use. It is there as a backup should I have a problem with the others. It is difficult to get to to view the water level, so, er, I haven't.

Yesterday I decided to use it to run the boat systems whilst on shore power. No problem, showing 12.6 volts pre-charging, everything working fine.

But around 10pm I started to smell something inside the boat. Didn't immediately think of the battery as it could be any number of things, even the boat in front of us whiffs when he opens his hatches.

After moving some flowers outside and taking the rubbish up the smell was still there.

Checked the batteries, the service one was incredibly hot! Obviously difficult to describe but I feared for the surrounding grp.

Turned the charger off and carefully, oh so carefully took off one of the filler caps. Empty!

It would NOT cool down, there was bubbling and gurgling ongoing.

I really couldn't leave it as for all I knew it was about to blow. Seriously scarey. My wife went to a friends boat and I sat there thinking of what would happen to me if it did 'go' but my overriding thought was to cool it so that couldn't happen.

I started to gently fill it with distilled water, each cell a bit at a time. 2 litres later no sign of it over the plates. Started to use tap water. It took >4 litres of water and a LOT of time before the plates covered.

Still really hot, and incidentally but confusingly, still showing 12.9 - 13.0 volts.

It wasn't until about 2am that I could feel it cooling and went to bed. My wife stayed on our friends boat but in contact.

So, in the best manner of 'what now skipper' what would you have done?

The battery is near inaccessible. It weighs 49 kilos. It was a bomb as far as I'm concerned. But not one I felt I could walk away from.

What would have happened if I'd managed to get it out, tie a rope onto it and lower it into the sea? A few dead fish of course but how does the acid react to salt water?

I don't think I could have carried it far but even if I could where could I have left it to not compromise passers by?

Call the local Fire Brigade equivalent ???

If it had blown before I had noticed it and we hadn't been personally affected would it have been a 'simple' case of just trying to dilute any acid with fresh water, massive problem working around the acid and of course everything around it is to do with the electrical supply so water not good, acid not good.

TBH I'm still a bit stunned. Stupid to stay? Yes. Stupid to go? Well, it wasn't cooling down and I still can't get over the heat, so I had to do something.

You?

 

[Bobc]

Blimey, that sounds scary! Well done in getting it cooled down. Not sure I would have done anything differently to you, but the "what if" thoughts after the event are probably more scary than dealing with it at the time.

I'll be interested to hear others views on what they might have done, and more importantly what you do in the situation of a battery exploding.

 

[PaulMcC]

No knowledgable advice on what you should have done. But I think I would have done the same thing in your place and would probably have been equally concerned.

 

[Just_sayin']

You've got it it one Bob.

I knew staying was, if not life threatening, very, very dangerous but I kept thinking 'I CAN/MUST cool this'

 

[lw395]

You've got it it one Bob.

I knew staying was, if not life threatening, very, very dangerous but I kept thinking 'I CAN/MUST cool this'

Adding water to acid releases heat!
It can explode.


Better to cool it by putting a wet towel on top/around it.

I suspect there was no acid, but I think what you did was risky.
Such is the luxury of hindsight, you did what you hoped was right and it worked out OK, but I would not advise people to copy what you did!

 

[SHUG]

Scary experience!!!
Clearly it is important to get the caps off to vent the gas BUT what do you do if a sealed battery starts to overheat in the same way?
Run, or throw it over the side?

 

[Just_sayin']

Adding water to acid releases heat!
It can explode.


Better to cool it by putting a wet towel on top/around it.

I suspect there was no acid, but I think what you did was risky.
Such is the luxury of hindsight, you did what you hoped was right and it worked out OK, but I would not advise people to copy what you did!

So you'd have wrapped it in a damp towel and gone to bed?

 

[lw395]

Scary experience!!!
Clearly it is important to get the caps off to vent the gas BUT what do you do if a sealed battery starts to overheat in the same way?
Run, or throw it over the side?

Personally I'd tie a rope around it and get it over the side.
I'd be careful taking the caps off too, getting sprayed with hot acid under pressure is not on my 'to do before I'm 60' list!

 

[lw395]

So you'd have wrapped it in a damp towel and gone to bed?

I'd have either got it off the boat or kept an eye on it until it was a lot cooler. Probably contemplated the gently steaming wet towel over another beer.
I've seen the aftermath of a few baby 12V batteries exploded, the sort used in burglar alarms.

The need to do something quick and heroic is often best left to cartoon characters.

 

[rob2]

I think you did the right thing. Once the charger is switched off (and any load) the isolated battery isn't going to get any hotter, nor will it explode, so getting some cold liquid in it will start to recover the situation. Of course, the plates may have deformed which will leave you with the biggest, heaviest 50aH battery ever! There is a little risk from the beast gassing until it's down to normal temperature, but I'm assuming you provided all the ventilation available to cool it. You're probably right that it wold have been difficult to find somewhere to put the battery where it wouldn't be a hazard to others - even just a trip hazard.

I have exploded a battery. For those who remember it, the Mini pickup had a battery under the floor behind the driver's seat with just the terminals sticking out. It isn't easy to move around in the small cab and a spanner dropped from my pocket across the terminals. By the time I lifted the seat and made a grab for it, the battery hissed and exploded. I probably broke some track record for getting to the loo and washing the acid off my face and then had to wash the whole area repeatedly - or face welding in a new floor... I borrowed a tractor battery to get home - I didn't need to run the engine, I could have done it on the starter!

Rob.

 

[lw395]

I think you did the right thing. Once the charger is switched off (and any load) the isolated battery isn't going to get any hotter, nor will it explode, so getting some cold liquid in it will start to recover the situation. Of course, the plates may have deformed which will leave you with the biggest, heaviest 50aH battery ever! There is a little risk from the beast gassing until it's down to normal temperature, but I'm assuming you provided all the ventilation available to cool it. You're probably right that it wold have been difficult to find somewhere to put the battery where it wouldn't be a hazard to others - even just a trip hazard.

I have exploded a battery. For those who remember it, the Mini pickup had a battery under the floor behind the driver's seat with just the terminals sticking out. It isn't easy to move around in the small cab and a spanner dropped from my pocket across the terminals. By the time I lifted the seat and made a grab for it, the battery hissed and exploded. I probably broke some track record for getting to the loo and washing the acid off my face and then had to wash the whole area repeatedly - or face welding in a new floor... I borrowed a tractor battery to get home - I didn't need to run the engine, I could have done it on the starter!

Rob.

A fat person in the back of a mini traveller could push the seat springs onto the battery when you hit a bump!
I remember the smoke coming from under the seat.

Plenty of Youtube vids of adding water to acid.

 

[Plevier]

I think you did the right thing. Once the charger is switched off (and any load) the isolated battery isn't going to get any hotter, nor will it explode, so getting some cold liquid in it will start to recover the situation.

Agreed.
You might have more risk of explosion if you try to disconnect it and make a spark, if it's been gassing rather than just boiling.
Adding water to concentrated sulphuric acid is dangerous, but not adding it to the battery, even if the level is low enough to have reduced the dilution somewhat.
If you are faced with spilled acid, the normal easily available neutralising medium is sodium bicarbonate.

Talking of explosions, I once had to inspect a 48V 2500Ah telephone exchange battery that had exploded (24 separate cells, each the size of a dustbin and holding about 100 litres of acid). They had been boost charging it with the vent plugs out (bad practise, the vent plugs incorporate ceramic flame isolators, same principle as mining lamps, and should be left in) and someone dropped a spanner on the main bare copper busbars (again bad practise, using non-insulated spanners in a battery room). The spanner half melted, dropped off and sparked and several cells went up. There were big shards of 6mm thick plastic stuck in the ceiling! Astonishingly only 1 person was slightly injured with scratches and acid burns. Rather scary.

 

[silver-fox]

I believe the right course of action would be: -

1. Isolate the battery
2. Look to apply something cooling to outside of battery (It may even be better to skip this stage)
3. Retreat to a safe distance and wait

Your desire to fix the problem and protect the boat, appears to have overcome your ability to measure the risk of intervention and consideration of the consequences (acid burns, death or injury from an explosion?). In the cold light of day we all know its people first and things a long way second.

You may not have qualified for a Darwin award this time but it was an attempt of some merit.

Am I any smarter? - probably not.

There is a saying "There are old sailors and there are bold sailors; but there aren't any old, bold sailors"

Of course none of my comments above apply if it was really a bungled suicide attempt.

 

[KellysEye]

> It is difficult to get to to view the water level, so, er, I haven't.

Moral of the story don't have a battery in a difficult to get to area so you can't add water - the outcome was obvious and happened. As said you were extremely lucky there was no acid when you added water otherwise you would have got a face full of slightly diluted acid. If it wasn't smoking I would have left it alone it would it would cool down eventually.

 

[VicS]

> It is difficult to get to to view the water level, so, er, I haven't.

Moral of the story don't have a battery in a difficult to get to area so you can't add water - the outcome was obvious and happened. As said you were extremely lucky there was no acid when you added water otherwise you would have got a face full of slightly diluted acid. If it wasn't smoking I would have left it alone it would it would cool down eventually.

Unless it had been physically lost, which would have been obvious, the acid would still have been in there. If the battery was completely discharged most would have been converted to lead sulphate but in any case, as Plevier says above, it it is not likely that it would have concentrated to the point where adding water would have been dangerous unless the battery was so simply so hot that the water boiled.

 

[Chris_Robb]

No comment on what you did, but what you do in the future might be to always have a maximum size of battery at say 110AH, each being of manageable weight. I had to chuck one 110AH over the side when it went beserk. I could not have done that with a 220 battery.

As you get older you will also totally wreck your back!

 

[black mercury]

Reminds me of a time when driving a mondeo I used to own. Starting smelling really strong acid smell in the car which was getting worse. Pulled over, popped open the bonnet and you could see the heat vapour coming from the battery. The battery was so hot you could push the sides of the casing in with a pen. I disconnected the alternator and drove home, the battery still able to start the car. First thought was the alternator was overcharging, but it was the battery itself, it wasn't accepting the charge that the alternator was pumping into it, was just getting hot instead. I do know that if you have a dead cell in a battery and you connect an automatic charger to it the charger will keep pumping current in because the voltage won't go high enough. That's why the more expensive marine chargers have a battery temperature sensor. Once a battery gets hot it does take a long time to cool, I probably would have done much the same, maybe even have poured water over the top to cool it.

 

[Otter]

OP- Sounds like you had a form of thermal runaway. I wouldn't have gone near the filler caps, you were a very, very lucky guy.

 

[david_bagshaw]

Dont think I would have moved it due to:-

1 spark on disconnection causing explosion
2 case would be weaker due to the heat
3 distortion of case might cause an internal short
4 if dropped in sea the electrolysis of sea water produces chlorine.

caps on and pour water over them if over 60 c, trying to keep terminals dry if posssible.

 

[lpdsn]

Personally I'd tie a rope around it and get it over the side.

That doesn't sound feasible if it's already so inaccessible it's a nuisance to check the water levels. It's not easy to lift 49Kg in a confined space - coincidentally my domestic batteries are the same weight so I know. I replaced one completely on my own but had to get help with the second as there simply wasn't the space to get into a position where I could hoist that weight.