Battery EXPLOSION RISKS !

[Leighb]

Some years ago we hired a yacht at Acle on the Broads. The yard guy took us through showing how things worked, fridge, cooker etc. He then showed how to start the engine. After showing the gear shift he then said, “To stop, just pull up this knob” This was a black knob by the side of the companionway. As he did so there was a flash and a bang and smoke coming up. It turned out that the chain that connected to the stop lever, old style lavatory type, had broken and fallen across the battery terminals!!!
”I will just have to fix that and get you a new battery and then you can be on your way “

 

[Bilgediver]

We had a battery explosion at our marina last year. A local group had come down to launch a RIB and found the trim motor would not operate and came looking for a battery . Some one came to my premises and we returned to the boat. He had been away less than ten minutes. During that time they had tried to jump start the battery resulting in an internal explosion which blew the top complete with terminal posts off the battery seriously wounding one person as it flew through the air. The thing I immediately noticed that there seemed to be no acid effect felt by anyone. Also I observed that the battery was maintenance free and the plates were only half the case height also there was no trace of any electrolyte! There is no way there was time for heat to be the cause. Could there have been an internal short and spark?

 

[Halo]

Thats why you should never wear a watch with a metal strap when working on an engine. If you forget to disconnect battery and manage to allow it to create a short on the large starter motor cables it can cause major injury by melting the strap and wrecking your wrist and hand

 

[ryanroberts]

CO detectors can pick up on a boiling battery before you do, at least with flooded cells Why is hydrogen such a big issue for CO sensors? | GfG Instrumentation | GfG Instrumentation

 

[GregOddity]

Removing battery cables from a gassing battery is extremely dangerous, there is no excuse for it. The battery should have been well avoided until the hydrogen had cleared.

If your battery is gassing (boiling, smell of hydrogen, CO alarm going off etc) turn the main isolators and any charging sources off and leave it alone until the hydrogen has cleared. The tiniest of sparks can ignite the gas and the battery will explode, literally, like a bomb. I have witnessed this first hand, flying fragments of battery case and boiling acid are not good for your complexion or eyesight.

Yes, removing cables from a very hot battery is something that should not be attempted. In this case, as I moved to feel the temperature of the battery with my hand, I accidentally touched one of the cables and it jumped up from the battery as it was completely loose. I touched the other cable and it also moved. I just pulled it up but in retrospect I should not have done so until the battery was within normal working range, the area was well ventilated and I switched off all power and disconnected mains to the boat and opened all hatches and lockers.

 

[GregOddity]

Personally I suspect the loose connections were caused by the battery overheating rather than v/v.
Overheating probably caused by drying out one cell. Inappropriate charging regime, and/or not recognising that the battery is at end of life?

Also I think moving a batttery when its internal temperature is grossly high is not a very good idea at all.
ISTM possible that the plastic case will be soft and a risk of internal shorts if it bends out of shape when you lift it?

Sometimes the best PPE you can get is a good pair of running shoes.

Moving the battery in this case was made easy by the fact that it's located on a side locker on the transom of a powerboat in this case. But as you very well point out there is indeed that danger. I must admit I never really had any training with incidents with batteries besides the “runaway fast”. I'm all for the running shoes. There's not a lot about how to handle a hot battery and the proper procedure or safety regarding hot batteries.

I’m also not the best person for that as while I was studying electronic engineering we barely touched the subject of batteries and in my professional life the only training I got on the matter was from other colleagues that had qualifications in electrical engineering but were not specially trained on the matter.

To be honest I only ever met someone that was really specialized in Batteries while working for Shell and because he did all the power banks for ROV’s.

 

[GregOddity]

We had a battery explosion at our marina last year. A local group had come down to launch a RIB and found the trim motor would not operate and came looking for a battery . Some one came to my premises and we returned to the boat. He had been away less than ten minutes. During that time they had tried to jump start the battery resulting in an internal explosion which blew the top complete with terminal posts off the battery seriously wounding one person as it flew through the air. The thing I immediately noticed that there seemed to be no acid effect felt by anyone. Also I observed that the battery was maintenance free and the plates were only half the case height also there was no trace of any electrolyte! There is no way there was time for heat to be the cause. Could there have been an internal short and spark?

I suspect that internal short and spark plus the the accumulation of hydrogen and sulfuric gases inside the battery would be the most probable cause.

 

[GregOddity]

OK so here is my stupid question. Is the danger of thermal runaway with loose terminals solely due to the potential malfunction of the temperature sensor?

There are no technical stupid questions. Just the ones not asked.
No, there's a host of other issues at play as well. Basically as the temperature goes above working limit the batery just starts soaking up all the current the charger can put out and the hotter the temperature the more current it will take which will cause it to get even higher temperature and so on. Loose connections are the plague of electrics and electronics. From high magnetic fields to short circuits. But im sadly not the best person to answer that in detail concerning batteries. The problem with temperature sensors in my experience is where they are installed. Nigel Calder has a good article on that and it makes very good reading. I'm going to have to brush up on the matter myself as I find myself lacking in the respect of batteries besides some basic knowleage.

here's the link to the article.
How batteries can explode - and how to avoid it - Yachting Monthly

 

[rotrax]

We made simple 2v cells in glass beakers at school. So did my Dad when he attended the Michael Faraday School in Walworth, London in the late 1920's and early 1930's.

I went on an Exide battery course in the 60's as an apprentice, at a depot in London.

One of our customers in NW London when I worked for Lucas Service used to rip the guts from flooded cell lead acid batteries and rebuild them.

I bought from them a pair of large 6v ones for my 1961 Diesel Landrover. They were half the price of the almost impossible to source new ones.

It is old technology - all the problems are well known and can easily be researched.

Having said that, loose terminals causing the problem in the OP was outside my considerable experience.

A good and informative thread - thank you GregOddity.

This shows what a superb source this forum is.

 

[MikeBz]

Thats why you should never wear a watch with a metal strap when working on an engine. If you forget to disconnect battery and manage to allow it to create a short on the large starter motor cables it can cause major injury by melting the strap and wrecking your wrist and hand

I remember my Dad doing that under the bonnet of a car in the late 60s or early 70s, in the days when the connections between cells were external. He shorted his watch strap across 2 cells, luckily he reacted instinctively to the spark and pulled his hand away before the strap welded itself to the battery, without injury. It taught me a lesson which I have never forgotten.

 

[JumbleDuck]

here's the link to the article.
How batteries can explode - and how to avoid it - Yachting Monthly

It's an interesting article, although as ever one needs to remember that Nigel Calder is an interested amateur. However, it doesn't say anything about loose terminals causing thermal runaway. Perhaps they encourage some chargers to apply to great a voltage in order to get a specified current flowing.

 

[lw395]

I suspect that internal short and spark plus the the accumulation of hydrogen and sulfuric gases inside the battery would be the most probable cause.

Every o level chemistry student has put a lighted splint into a testube of hydrogen and oxygen from electrolysing water?
You get a little pop.
You would need a fairly serious volume of fairly pure H2/02 mixture to do serious damage.

Batteries mostly explode because of the electrical/chemical energy stored. 100Ah battery at 12V, that's 4.3MJ
Letting that out all at once is a lot of power.
The energy in Hydrogen is 142MJ/kg, which is a lot but a kg is 10 cubic metres of pure H2. The amount you get from overcharging a normal battery isn't going to be very exciting, even if you manage to collect it all, none of it diffuses away etc. And every schoolboy chemist knows that hydrogen gas is very good at escaping.
Unless you've got a big airtight shed full of forklift batteries, or a ww2 submarine, the main danger is in the stored electrical energy.
So, I would never move an overheated battery. Allow it cool. Even then be very careful.
Better not to go there. If you charge your batteries hard, keep an eye on the temperature.

 

[rotrax]

Well, from direct experience, I beg to differ.

I joined a major Japanese motorcycle manufacturer's technical dept. in the mid 70's.

The bloke I took over from as Trainer for the dealer mechanics had been shifted into the warranty department as he was not a very good trainer.

He had set up the workshop for the preparation of the press demo bikes. He was the best in the world at designing and building a motorcycle workshop.

I know this was true as he kept telling me so...........................

Well, he had made a nice two shelf tall and narrow bench for charging batteries. Charger fixed on the wall, bus bars and short cables with crocodile clips to join to the terminals.

On the very top of this narrow unit he fixed the twin wheel bench grinder.

One day, a battery from a Z750 twin charging well, he decided to do a bit of grinding.

The stream of sparks from the grinding wheel went downwards, igniting the gas from the the busily gassing battery, opening it up as it exploded with a dull thud.

Buggered his clothes from the waist down - the battery was on the middle shelf.

Compared to a car battery, it was tiny. But as ALL cells vent through one outlet on Yuasa motorcycle batteries, enough gas was present to cause the explosion.

True knowledge is the product of direct experience.

 

[Jim@sea]

This is a very extreme case, thanks for sharing!
Unfortunately, the danger start much earlier the at the melting point of the battery. At the point of overcharging L/A battery starts to release hydrogen, even before its temperature becomes to rise significantly. This is valid even for valve-regulated units and to some degree for marine-grade calcium battery. Hydrogen/air mix is highly explosive in a wide range of ratios and ignites upon receiving an intense look by your eye.
I was lucky to learn this lesson cheaply a few years ago when hydrogen exploded in my engine compartment. Fortunately, the floorboards were not screwed down. They just lifted up a few cm acting like a safety valve, then fell down again. No damage, no injuries.

Beware of batteries in enclosed places.
I had a HGV with the batteries in an enclosure under the body. The truck would not start. I called out an Auto Electrician. I told him the batteries were fully charged.
The first thing he went to do was to touch the electrodes of a heavy discharge meter onto the battery lugs.
The spark of the electrodes touching the battery lugs ignited the fumes from the recently charged battery and the battery exploded.
Covering the Auto Electrician in acid and blasting the battery casing into bits.
As a professional Auto Electrician he should have listened when I told him the batteries were charged.
He peobably thought I was a somple farmer and did not believe that I was competent to say the batteries were fully charged. (25 years with a garage)

 

[penberth3]

…..The energy in Hydrogen is 142MJ/kg, which is a lot but a kg is 10 cubic metres of pure H2. The amount you get from overcharging a normal battery isn't going to be very exciting.....

You're missing something there. What you have to consider is the explosive limit of the gas/air mixture. Don't know what it is for Hydrogen but it starts at 5% for methane - i.e. 1/2 cu m of gas in your 10 cu m.

 

[JumbleDuck]

Batteries mostly explode because of the electrical/chemical energy stored. 100Ah battery at 12V, that's 4.3MJ
Letting that out all at once is a lot of power.

The traditional route when electricity goes astray near water is short circuit -> steam explosion -> hydrogen explosion. It does seem unlikely that a battery or even a battery compartment could store enough hydrogen to make much of a bang.

 

[penberth3]

The traditional route when electricity goes astray near water is short circuit -> steam explosion -> hydrogen explosion. It does seem unlikely that a battery or even a battery compartment could store enough hydrogen to make much of a bang.

But it does happen. Not sure what you meant by "steam explosion".

 

[JumbleDuck]

But it does happen. Not sure what you meant by "steam explosion".

Explosive formation of steam as a result of electrical heating of water. Generally followed by rapid electrolysis of the remaining water, then a hydrogen explosion. I have no doubt that batteries can explode, but remain skeptical that it's a hydrogen explosion.

At Fukushima Daichi, by the way, the zirconium fuel rods reacted with steam to produce hydrogen in huge quantities - zirconium is unaffected by water thanks to a thin oxide layer but reacts very fast indeed with hot steam.

 

[PaulRainbow]

Every o level chemistry student has put a lighted splint into a testube of hydrogen and oxygen from electrolysing water?
You get a little pop.
You would need a fairly serious volume of fairly pure H2/02 mixture to do serious damage.

Batteries mostly explode because of the electrical/chemical energy stored. 100Ah battery at 12V, that's 4.3MJ
Letting that out all at once is a lot of power.
The energy in Hydrogen is 142MJ/kg, which is a lot but a kg is 10 cubic metres of pure H2. The amount you get from overcharging a normal battery isn't going to be very exciting, even if you manage to collect it all, none of it diffuses away etc. And every schoolboy chemist knows that hydrogen gas is very good at escaping.
Unless you've got a big airtight shed full of forklift batteries, or a ww2 submarine, the main danger is in the stored electrical energy.
So, I would never move an overheated battery. Allow it cool. Even then be very careful.
Better not to go there. If you charge your batteries hard, keep an eye on the temperature.

That's wrong, batteries will explode due to hydrogen being present.

Been there, got the tee shirt (full of holes from when the battery exploded), real World experience. Back in the early 70's when i was training as a mechanic, i was asked to take a battery off charge. No-one mentioned turning the charger off first. Old style battery, old style charger, been gently bubbling away all night, fitted to a car. When i removed the crocodile clips from the terminals there was a spark and the battery exploded in my face. Bits of battery went all over the place, as did the acid. I was very lucky to escape without injury.

 

[GregOddity]

I must pass on the chemical part of it. I did the basic electrolysis of water and made the famous pop that every student does but besides some very basic knowledge I got nothing to add. Batteries are such a specific field that you really need some proper expertise to be able to make an authoritative comment on the subject. Me not being one.
My intention with this thread was exactly to call attention to the fact that so little is available in terms of what to do when. My own actions could have been safer had I had more training than the run away or don’t touch.
Don’t touch,
Ventilate,
Switch all power off,
Keep distance,
Wait to cool.
Being the take away from a situation like this.