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

[Chris_Robb]

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.

When we had our runaway battery, we had battery sensing temperature on the Sterling charger. Unfortunately it is only on one battery............ a 4 in 1 chance..... Some form of overall battery temp alarm would be very useful on all the batteries.

 

[Interlude]

I think I am now motivated to install some temperature sensors / alarms to the batteries ...... mine are sealed out of sight and out of mind.

 

[Chris_Robb]

I think I am now motivated to install some temperature sensors / alarms to the batteries ...... mine are sealed out of sight and out of mind.

I don't know that a multiple battery temperature thingy exists. Perhaps a clever forumite could do one - say up to 4 batteries? I would buy it. I had an exhaust temperature warning buzzer off someone on here - which works a treat - only I have not had a real incident yet for it to buz - only tested by lowering the temperature.

 

[lw395]

I think I am now motivated to install some temperature sensors / alarms to the batteries ...... mine are sealed out of sight and out of mind.

Good idea if you use an 'aggressive' charger.
You can get little LCD thermometers with sensors on leads about a metre long very cheaply on eBay.
Maybe there's a market for a circuit to turn the welly down if any battery gets too warm?

 

[Norman_E]

Good idea if you use an 'aggressive' charger.
You can get little LCD thermometers with sensors on leads about a metre long very cheaply on eBay.
Maybe there's a market for a circuit to turn the welly down if any battery gets too warm?

We need a YAPP for this, Where is Angus? We need him to figure out how to do it and make the circuits. Those little LCD thermometers are cheap enough to buy just for the temperature sensor and if their display can be incorporated so much the better. A system that operated a circuit breaker on the battery charger mains input would be good, but a simple system that just sounded an alarm would be nice.

 

[Billows]

I think you acted foolishly.
Heat,pressure,acid in a confined space.I would have turned the isolation switch to off, vacated the boat and phoned the fire brigade.

 

[mezereon]

Really useful thread, thanks for starting this.
I have no idea what I would have done, I've never considered exploding batteries before. However, I've learned lots from reading comments here and I'll certainly be much safer if ever in a similar situation.

 

[Norman_E]

I have had an open cell battery that got pretty hot because the electrolyte level was too low. I have now replaced it with a sealed battery like the rest. Provided there is no fault like a short circuit (internal or external) boiling it up or a low electrolyte level a battery should not overheat, though in hot climates they can get fairly hot, but not dangerously so. In my opinion open cell batteries are a bad choice in a hot climate, because they do evaporate water from the electrolyte too easily, and if you do not notice they will overheat when charged. I have had no problems with sealed batteries.

 

[westernman]

I think you acted foolishly.
Heat,pressure,acid in a confined space.I would have turned the isolation switch to off, vacated the boat and phoned the fire brigade.

I would have waited rather than immediately phone the fire brigade. But I agree with the rest.

 

[pmagowan]

I don't know that a multiple battery temperature thingy exists. Perhaps a clever forumite could do one - say up to 4 batteries? I would buy it. I had an exhaust temperature warning buzzer off someone on here - which works a treat - only I have not had a real incident yet for it to buz - only tested by lowering the temperature.

There was one in a PBO not long ago.

 

[rob2]

There was one in a PBO not long ago.

Indeed, and each sensor and indicator was around a fiver! I don't know whether the indicators offer any switching capability, but if they do adding a relay for each would allow the charger to be cut off as the temperature rose.

Rob.

 

[Just_sayin']

Thanks for all the (varied ) responses.

I've had time to think them over.

Towel? Hot within minutes and the necessity to get really close to the battery. No.

Pour water around the battery? Interesting idea but there are only small gaps between the batteries. I'd ultimately end up with warm/hot water needing to be removed. How?

Walk away? When do I come back? A few hours? Next day? If it's a ticking bomb it could just as easily explode as I approach it in the morning. Remember, it was really hot even after being disconnected and, from the noises, there was a definite chemical reaction ongoing.

Yes there was a risk involved in working on it but:

I was wearing reasonably thick overalls over some old clothes, heavy gloves and had a sort of hoodie on plus some safety specs. All these from my anti-fouling box.

I was in constant phone contact with my wife.

I had opened the shower door and moved the shower head so that even with my eyes closed (or worse?) I could wash off quickly.

I worked at arm and fingers length and undid the first filler cap with more delicacy than you would open a shaken-up fizzy drink on an expensive carpet. There was no release of pressure, which surprised me.

The initial filling of the cells was done with a hydrometer at an even greater distance. Very time consuming but as safe as I could do it. I was very surprised that there was no sign of steam or extra gurgling. The initial input could just have evaporated, I was also surprised that I used > 4 litres of water.

So, now the critical question. What would I do should it ever happen again?

Yes, I recognised the risk. Given that, and given the fact that leaving it alone solved nothing - it could have exploded next morning - I would do the same again.

Everything I did was 'managed' from protecting myself, having contact with someone, to being ready to leg it if I was unhappy at any stage of undoing the caps to starting refilling.

As for calling the Fire Brigade, I think that a well equipped person prepared to simply cut through all the cabling and strapping 'could' have had the battery out in probably three minutes, there were other batteries that needed moving.

But if it had exploded as he was doing it? I know how I'd feel if he was hurt.

Hmm.

No, I'm not saying what I did was the absolutely right thing to do, but like the time I foolishly used to jump out of planes, I dealt with any issues at the time. Same this time. Thanks again.

 

[Scotty_Tradewind]

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.

+1

 

[Concerto]

The only thing you might have found useful would have been phoning the fire brigade for advice. They would have given suggestions on what to do and that might have been leave it to them or exactly as you did.

 

[Just_sayin']

The only thing you might have found useful would have been phoning the fire brigade for advice. They would have given suggestions on what to do and that might have been leave it to them or exactly as you did.

Thanks but my Spanish isn't that good :ambivalence:

 

[VicS]

Many references in the thread to "pressure" and "exploding"

Ok batteries can explode if the hydrogen/ oxygen mix is ignited but that aside are they really likely to build up pressure and explode. All batteries are vented, even sealed ones.
In the OP's case they clearly were not pressurised as he was able to remove the filler caps without incident.

Dunno what I would have done.

Dunno what would have been the most sensible thing to have done.

Switch off the charger and just allowed to cool perhaps ???

 

[Beyondhelp]

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.

Lead acid do not thermal run-away. Cells however do go short, and if trying to charge a battery with a shorted cell will result in massive over charge and over heating. Also if a cell goes short, that single cell will die producing heat whilst it does. There is NOTHING you can do to stop this.

As a side note this thread scares me. OP, I've seen batteries explode. When I was early teens I had a go-kart powered by a car battery which was on charge. My dad forgot/didn't realise and was cutting metal in the garage, the battery exploded. He was ok, after a quick shower... there was nothing much left of the battery. Now this in the confined spaces of a boat I'm SURE would have put you in hospital. More recently a car garage next to my old unit was charging a battery in his workshop and also cut some metal, the battery in there exploded in the same way. It was no less frighting than the first time I saw/heard it happen.

There are two real dangers here. Firstly the gas released by the battery is hydrogen and oxygen. Pretty damn easy to ignite. Secondly the acid, and the toxic fumes produced. Now for me had this been my boat I would have Isolated the battery from its supply via the battery isolator, then I would have kept well away from it and opened any vents/windows and left it for a time.

There is no way having first hand experience on this I would have dared to even approached the battery once I found that was at fault and having isolated it, not in a million years. IMHO trying to pour water into it or remove the valves whilst under this condition is a death wish.

Lead acid batteries have breather valves. And ideally the gasses from them should be vented to the atmosphere. This doesn't seem to happen in boats, which surprises me, but they DO NOT explode due to pressure, provided the vents are working as they should have been (and in this case were)

So to summarise, IMHO if a cell goes short, and the battery begins to over heat or if for some reason you discover your battery overheating I'd suggest the following:

1, ISOLATE LOAD DO NOT remove battery terminals from the battery, unless an even more extreme risk of something even more severe than battery explosion is imminent. Ensure ignition suppressed battery isolators are fitted. They should be anyway.

2, VENTILATION Open windows/doors/hatches and allow the gasses to escape from the boat.

3, KEEP AWAY Stay out of harms way for enough time for it to cool down, Probably an hour or so will do.

Once cool remove and dispose of the battery, test charging system refit new battery and continue life as normal.

BTW the smell you could smell was the fumes when heated to decomposition, its quite a sharp nasty and unique smell. I doubt you will ever mistake it again.

 

[RobbieW]

I've had the same situation as the OP whilst delivering a boat, Hamble - Plymouth. Boat had no heating, November'ish, middle of Lyme Bay suddenly noticed the nav seat was hot. Lifted and found one battery was even hotter, we'd motored all the way so it had been getting a charge for about 10 hrs. Disconnected hot battery, checked it near Dartmouth - no better or worse to the touch. Carried on to Plymouth when it had cooled but was still noticeably warm to touch about 10 hrs later.

I dont remember the thought process now but I'm pretty sure that it was along the lines of removing the immediate cause of the problem then stay away from the hot battery.

 

[Otter]

Lead acid do not thermal run-away.

Nigel Calder says they do and to keep an axe on board for emergency cable cutting. He describes it as a process by which the raised temperature allows the battery to accept more and more charge, thereby increasing the batteries' ability to accept charge and so on in a vicious cycle of ever increasing battery temperature until it ruptures. I trust Nigel's opinion.

 

[westernman]

...

Thanks for sharing your experience and confirming my intuition (disconnect and run away).