Exploded battery

[RLWP]

At 5:00am, this battery blew up, lifting the deck board above it:

 

 

It looks like five of the cells exploded, wrecking the case:

 

 

As the damage included the sides splitting, about half of the acid ran out into the battery box:

 

 

As part of the cleaning up, I drained the battery, here's the acid:

 

 

I would say that this battery had become pretty sulphated, I'm not an expert on this though.

 

This was one of a domestic bank of six batteries, all charged up by an Adverc. The boat was used to living on a landline, but has spent a long summer out on the cut, not being used. More than once the batteries had become dead flat.

 

It looks to me that, although four of the batteries seem to have recovered (unscientific test - I can see the green ball), one is sat taking six amps in my workshop, and this one exploded.

 

I do wonder about these large battery banks with automatic chargers

 

Richard

[Guest]

 

I do wonder about these large battery banks with automatic chargers

 

Richard

 

We came close to the same in the summer but luckily we were cruising when the battery started to massively 'fizz' and overheat.

 

Fortunately when we got back to the pontoon our combi. wouldn't go into to charge mode because the temp sensor picked up the battery was overheating, this is what caused me to investigate, had it been one of the others in the bank though we would likely have just merrily connected the charger and left the boat as usual - and likely come back to the same scenario.

[Gibbo]

Here is what probably happened...

 

The entire battery was getting somewhat kackered with partial short circuits and just a general mess inside. The cell that didn't explode had a complete short therefore no voltage across it during charging. Consequently the other cells all got overcharged (over-voltage). This causes them to gas like mad. One of the partial shorts in the other cells then "arced" blowing up that cell. The exploding gasses will have ignited the remaining 4 cells (which will all have been full of hydrogen and oxygen).

 

Just my guess.

[Rebotco]

That is a graphic warning to the rest of us! Were these sealed batteries?

[Gibbo]

That is a graphic warning to the rest of us! Were these sealed batteries?

 

Not any more

[RLWP]

Here is what probably happened...

 

The entire battery was getting somewhat kackered with partial short circuits and just a general mess inside. The cell that didn't explode had a complete short therefore no voltage across it during charging. Consequently the other cells all got overcharged (over-voltage). This causes them to gas like mad. One of the partial shorts in the other cells then "arced" blowing up that cell. The exploding gasses will have ignited the remaining 4 cells (which will all have been full of hydrogen and oxygen).

 

Just my guess.

 

I agree with the overheating plus oxygern/hydrogen mix - the burst out top confirms that nicely

 

As it happens, the cell that didn't blow was the one with the green tell-tale, showing green

 

Any thoughts on battery chargers and their ability to explode batteries?

 

Richard

[Guest]

That is a graphic warning to the rest of us! Were these sealed batteries?

 

They look like they have screw out 'top up' plugs to me.

[Rebotco]

Not any more

 

:D:D

[RLWP]

That is a graphic warning to the rest of us! Were these sealed batteries?

 

They're Numax 135 batteries. This site says:

 

L135 cyclic sealed leisure batteries.

 

Richard

Edited November 17, 2012 by RLWP

[Gibbo]

Any thoughts on battery chargers and their ability to explode batteries?

 

Yes. They're all capable of it

 

The only possible safety trick that would guarantee safety would be a gas detector in the battery compartment linked to the charger. This would only work with vented batteries. Temp sensing wouldn't work reliably in all cases.

[Guest]

They look like they have screw out 'top up' plugs to me.

 

... or maybe not.....

[RLWP]

They look like they have screw out 'top up' plugs to me.

 

They are indeed plugs. One had blown out.

 

Richard

[Gibbo]

They look like they have screw out 'top up' plugs to me.

 

Even the fully sealed ones have those. They have to get the acid in at the factory somehow. They're then usually glued in.

[Guest]

Temp sensing wouldn't work reliably in all cases.

 

That would seem to be the case in our 'near miss'.

 

The sensor happened to be adhered to the battery that went belly up - if it had been connected to any of the others I seriously doubt whether I would have been alerted to a problem.

[RLWP]

Yes. They're all capable of it

 

The only possible safety trick that would guarantee safety would be a gas detector in the battery compartment linked to the charger. This would only work with vented batteries. Temp sensing wouldn't work reliably in all cases.

 

These batteries have a small block on the side with an attachment for a tube. I assume this is the vent?

 

Richard

[Gibbo]

These batteries have a small block on the side with an attachment for a tube. I assume this is the vent?

 

It could well be. Some are a free vent, some only vent when the internal pressure builds up. With the latter, it can be too late by the time it lets go.

[RLWP]

It could well be. Some are a free vent, some only vent when the internal pressure builds up. With the latter, it can be too late by the time it lets go.

 

I'll dissect the corpse to see what's what

 

Richard

[ChimneyChain]

That happened to my mate at work. He put two big truck battery's on charge overnight, came in the next morning tested them with a drop tester and BANG, luckily no acid went into his eyes but his face was rather red for a couple of days after that. And the morel of the story is don't put sparks anywhere near a freshly charged battery.

 

Darren

[by'eck]

At 5:00am, this battery blew up, lifting the deck board above it:

 

It looks like five of the cells exploded, wrecking the case:

 

As the damage included the sides splitting, about half of the acid ran out into the battery box:

 

As part of the cleaning up, I drained the battery, here's the acid:

 

I would say that this battery had become pretty sulphated, I'm not an expert on this though.

 

This was one of a domestic bank of six batteries, all charged up by an Adverc. The boat was used to living on a landline, but has spent a long summer out on the cut, not being used. More than once the batteries had become dead flat.

 

It looks to me that, although four of the batteries seem to have recovered (unscientific test - I can see the green ball), one is sat taking six amps in my workshop, and this one exploded.

 

I do wonder about these large battery banks with automatic chargers

 

Richard

 

Don't blame it on the charger automatic or not. Its down to lack of awareness. Batteries don't suddenly explode. Tell tale signs of impending explosion are:

 

Individual batteries getting unusually hot

High current being drawn from charger even when apparently fully charged

Strong sharp smell of hot battery electrolyte

Battery case bulging or split, leaking electrolyte

Battery bank self discharging (into faulty battery(s))

 

If any of these symptoms, switch off charger, identify faulty battery(s) and disconnect from rest of bank with some urgency.

 

Sulphation doesn't cause them to explode, internal shorts (partial or full) on individual cells do. This topic comes up regularly and the answer is invariably the same sealed or not.

[mrsmelly]

I agree with the overheating plus oxygern/hydrogen mix - the burst out top confirms that nicely

 

As it happens, the cell that didn't blow was the one with the green tell-tale, showing green

 

Any thoughts on battery chargers and their ability to explode batteries?

 

Richard

 

We check our batts at work including specific gravity, voltage terminal condition etc every three months religously and keep a log of each battery ( we have around 30 ish ) The batts on one boat were checked last month and all were in very good condition. I went to start one engine a couple of weeks ago and one of the batteries had done exactly the same and blown most of the top off. A scary thought for me is that it could have gone bang in my face at anytime and that doesnt bare thinking about.

 

Tim

[RLWP]

This is certainly a good set of indicators. I've appended some real-life observations:

 

Don't blame it on the charger automatic or not. Its down to lack of awareness. Batteries don't suddenly explode. Tell tale signs of impending explosion are:

 

Individual batteries getting unusually hot - batteries under floor, well away from normal contact with user

High current being drawn from charger even when apparently fully charged - there was no certainty about the state of the batteries. This is a large bank that had got very low - beyond what could easily be replaced by cruising. So, there was a lot of current going into the bank anyway.

Strong sharp smell of hot battery electrolyte - not present until after the battery burst

Battery case bulging or split, leaking electrolyte - see point one

Battery bank self discharging (into faulty battery(s)) - how could a user know this?

 

 

I think that this does show that large banks with sophisticated charging systems are not fit-and-forget

 

Richard

[David Schweizer]

This is certainly a good set of indicators. I've appended some real-life observations:

 

 

 

I think that this does show that large banks with sophisticated charging systems are not fit-and-forget

 

Richard

Your story makes me rather grateful for our comparatively simple system of two 6volt Extra Deep Cycle batteries, and a Sterling Alternator Regulator. I have a volt meter installed to monitor them which I check every morning, hopefully there is a chance that I would get a bit of warning if one of the cells went down.

[mango]

For temperature sensors to warn of a shorted cell, every battery would need a sensor.

 

Perhaps the vent tubes of the batteries could be connected to a manifold and a single flow or pressure sensor used to detect abnormal gassing.

[nb Innisfree]

Batteries don't suddenly explode.

 

BBBBBBAAAAAAANNNNNNNGGGGGGGG

[MtB]

Sulphation doesn't cause them to explode, internal shorts (partial or full) on individual cells do.

 

This comment intrigues me. What exactly is an 'internal short', in detail, please?

 

And how can an internal short circuit be partial? Surely this is an oxymoron.

 

Thanks,

Mike