Battery Explodes!

Art- Had a funny experience with a similar safety program at a commercial nuke power plant. They called it "STAR". Stop, Think, Act, Review. We had been having a number of embarrassing screw-ups, and this STAR thing was some MBA's idea to fix things. Not a horrible idea at all, and things did improve.

But us in the field had a little fun with it: Two versions.

STAR- Stop Turn and Run

Second one:

STAR- Start Typing Another Resume

I'm just avoiding going out and cleaning the mess in the shop...

Ski in NC said:

....

Preheat it for 15sec, hit start and rrr-rrr-rrr-BANG!! ....

I knew the batt was a little weak as it was a grp 31 deep cycle that was becoming too weak in the boat. But it started the gennie ok (barely of late)...

It was on a battery tender....

So be careful with batteries!!

I am lucky, but still have a mess to clean up.

Third battery explosion I have been involved with in last 15yrs. Not sure I like batteries any more.

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Re: "I knew the batt was a little weak..."

The first (and nearly universal) failure mode of multi-cell batteries of any type is when one cell goes bad. It almost never happens that all cells degrade equally at the same exact rate, so the 'end stage' of a failing battery is always the same -- single cell failure. If that cell fails 'open', the battery just stops working, neither able to accept charge or deliver. The dangerous (and more common) failure mode is when a cell fails shorted. Now in the case of your group31 (6 x 2.1v cells), this means you no longer have a 12.6v battery, you now have a five-cell, 10.5v battery. The only initial symptom will be that the battery drops below 12.6v within a short time after charging stops. Most of the equipment hooked up to that battery (including cranking motors) will still work with a five-cell battery, but the problem is when you charge it...

Re: "It was on a battery tender."

This is the thing that sealed this battery's fate. Your battery tender thinks it was hooked up to a 12.6v battery, but in reality it was hooked up to a 10.5v battery. That means the remaining (non-shorted) five cells were constantly being overcharged, because the battery tender is designed to charge to 13.6v, then taper off. This in turn means the remaining five cells were outgassing hydrogen at a dramatically higher rate than they should have been. A healthy battery in a well ventilated space, being charged within it's design specification will not make enough hydrogen to explode.

Re: "Third battery explosion I have been involved with in last 15yrs."

It's very tempting to 'repurpose' batteries that have become "a little weak". Don't do it. Especially, don't leave them connected to a continuous charging source -- even if it's just a little one. A bigger charger would have boiled the electrolyte and sent it spewing out of the vent caps...as it was your smaller charger only provided enough current to make a lot of hydrogen.

As far as the ignition source...when battery terminal connections become loose or develop corrosion between the mating surfaces, resistance builds up slowly. Then, when you all of a sudden try to pull huge current through that resistance, a tiny spark happens and (if your five-cell battery is making lots of hydrogen), ka-boom.

This is much more common (and likely) than an internal short between plates.

Most of us have gotten behind the wheel of a car, turned the key, saw the lights come on and then at the instant you try to crank, the battery immediately goes flat dead---lights out dead. At the moment you tried to crank, that little spark fried the last remaining conductive surface contact. Then, after cleaning the terminals, you find the battery tests just fine.

re: "Not sure I like batteries any more."

Old, weak batteries are very dangerous, which is why I get rid of them.

Glad you weren't hurt and we can all learn from this. Also, lucky that you got that battery out of your boat -- there'd have been much more damage inside your boat I think...

Could it have frozen over the winter and discombobulated the plates to a short?

Ski in NC said:

Art- Had a funny experience with a similar safety program at a commercial nuke power plant. They called it "STAR". Stop, Think, Act, Review. We had been having a number of embarrassing screw-ups, and this STAR thing was some MBA's idea to fix things. Not a horrible idea at all, and things did improve.

But us in the field had a little fun with it: Two versions.

STAR- Stop Turn and Run

Second one:

STAR- Start Typing Another Resume

I'm just avoiding going out and cleaning the mess in the shop...

Click to expand...

Cool!!

Understood... re shop clean.

Tom.B said:

Could it have frozen over the winter and discombobulated the plates to a short?

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Not suspecting freezing. Shop is insulated and heated. I don't leave the heat on unless working in there but even with heat off the coldest I have seen in there was 45F and that is with outside 15-20F. Never had anything freeze in there. Thick slab with 2 1/2 walls below grade. Lots of thermal inertia.

Riverguy- agree with what you posted about one shorted cell being likely cause of this.

Ski, very glad you're ok. Obviously you were close, so it could have been bad. Many years ago I had a battery blow up in my face. By some miracle, no acid in my eyes. Now I *always* wear safety glasses when working on batteries.


Ken

Ski glad to hear your okay.
The STAR story reminds me of the Navy forming a “fast action responce team” to do emergency ship board repairs. Great idea till the acronym was painted on thier hard hats !

HiDHo said:

Ski glad to hear your okay.
The STAR story reminds me of the Navy forming a “fast action responce team” to do emergency ship board repairs. Great idea till the acronym was painted on thier hard hats !

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Now that's funny. Some idiot did not think this through LOL
When they had a meeting, was it called a FART Meeting?

I was in the US Navy for 7 years.

Wow Ski glad you’re ok. I was just down below the other day starting my old Westerbeke with the engine panel controls and the battery right next to me.Mine is slow starting after winter layup . I was having to hold in on glow plug longer than normal. I think I probably have low compression. Now I’m creeped out. I think I’m gonna be building me some battery boxes or buying some.
Is it ok to build them out of a decent grade of plywood with a top? I have a bunch scrap pieces laying around that aren’t good for much. Does the box need holes in it so battery can vent?

Thanks for posting this as a lesson to us all, Ski. As others have said, glad you're OK but...what a friggin' mess that must be! I imagine you're still out there cleaning up the shop as I sit in my warm kitchen sipping coffee.

I think I'll amend my SOP and turn off the battery charger before checking my 6xGC house bank water levels. I'll also mechanically ventilate the area before popping the caps.

Lessons learned!!!

Would a heavy duty box like this contain that kind of blow?

Use the box to contain the "blow-up", but vent it to get rid of the H2

Yes, GLAD no injuries, and a good lesson for all.

Question: are sealed batteries any safer?

Ski in NC said:

Art- Had a funny experience with a similar safety program at a commercial nuke power plant. They called it "STAR". Stop, Think, Act, Review. We had been having a number of embarrassing screw-ups, and this STAR thing was some MBA's idea to fix things. Not a horrible idea at all, and things did improve.

But us in the field had a little fun with it: Two versions.

STAR- Stop Turn and Run

Second one:

STAR- Start Typing Another Resume

I'm just avoiding going out and cleaning the mess in the shop...

Click to expand...

Start Typing Another Resume...love it!

Seevee said:

Question: are sealed batteries any safer?

Click to expand...

Don't know the answer to that, but there are two kinds of "sealed" -- one being the standard automotive no-maintenance type, and the other being Valve Regulated. I think the latter, VRLA (as in AGM and Gel), isn't really completely "sealed" but offers some of the same benefits (e.g., "no" -- meaning much reduced -- maintenance).

-Chris

Pack Mule said:

Would a heavy duty box like this contain that kind of blow?

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most of those box's only use 1/4-20 hold down's. i seriously doubt it would contain the boom. but it would definitely help keep most of the parts, acid contained to a much smaller area.

Riverguy said:

Start Typing Another Resume...love it!

Click to expand...

Luckily... always having had my own businesses [6th grade onward...] I have only needed to read resume/CV from interested parties to work for/with me.

Mine would simply say "Self"... please feel free to call 4xx 4xx 4xxx! LOL

RIVERGUY thanks for the long summary. It reminds me of another reason why I’m a proponent of 2V batteries in series.

Show and tell.

Actually a grp 24 starting batt that was in the boat for the thruster.

Nice! That's a beauty. Hope nobody was hurt.

Glad it turned out well, injury wise Ski. That blowed up real good...

ROFLMAO! Good one, RTF!

Blow'd up real good!!!

Mean Time Between Failures; Battery RAID math?

makobuilders said:

RIVERGUY thanks...it reminds me of another reason why I’m a proponent of 2V batteries in series.

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Yes...and I thought I was the only one thinking this way.


In my previous life (pre-semi-retirement), I was a reliability engineer for data storage systems (R.A.I.D., for Redundant Arrays of Independent Devices).


A six-cell battery is a terribly unreliable configuration, because the MTBF of the battery (or 'six-cell RAID-0 array') is exactly one-sixth of the MTBF of a single cell.

IIRC, all the Ni-Cad batteries I grew up with in aviation were a compilation of 2V cells. They had issues and came complete with battery temp indicators that required gauges and idiot lights. We had Abnormal and Emergency Procedures to deal with the elevated tempswith an amber/red light. The first act to avoid a thermal runaway was always to disconnect the charge source.

They claimed the advantage of the 2V cells was to avoid the cell-to-cell migration of a failure. Is that accurate?

Years ago there was a local guy who was finishing the interior of a sailboat. While working on it, it was believed that he dropped a wrench, shorting the battery terminals. The resulting explosion was catastrophic.

I'll never forget looking at the x-rays in the hospital Imaging Department one night. There wasn't a single major long bone that wasn't fractured. I can't recall if he ultimately survived; he was alive when the helicopter took him to the regional trauma center.

Battery box "adding to the shrapnel?" No, that's not the concern. The pure blunt force trauma, not to mention the acid, is devastating; anything that contains it is desirable. Of course, those el cheapo battery boxes that most folks have on their outboard runabouts aren't what we're talking about. The battery boxes on Kingfisher are extremely heavy polyethylene with welded seams; I could use them to block up my truck.

Wow! Sounds powerful!

I used to think that my molded-in fiberglass boxes and painted plywood covers were sub-standard but I think they'd be far superior to a battery explosion like that in a thin plastic box with a screw lid. The way mine are configured, lids could blow vertically 2-3 ft, but the contents would be contained within the rigid boxes.

This thread has me thinking again about battery safety...before I get blow'd up real good.

Sabre602 said:

Years ago there was a local guy who was finishing the interior of a sailboat. While working on it, it was believed that he dropped a wrench, shorting the battery terminals. The resulting explosion was catastrophic.

I'll never forget looking at the x-rays in the hospital Imaging Department one night. There wasn't a single major long bone that wasn't fractured. I can't recall if he ultimately survived; he was alive when the helicopter took him to the regional trauma center.

Battery box "adding to the shrapnel?" No, that's not the concern. The pure blunt force trauma, not to mention the acid, is devastating; anything that contains it is desirable. Of course, those el cheapo battery boxes that most folks have on their outboard runabouts aren't what we're talking about. The battery boxes on Kingfisher are extremely heavy polyethylene with welded seams; I could use them to block up my truck.

Click to expand...

And Lithium is supposed to be dangerous.

Sabre602 said:

Years ago there was a local guy who was finishing the interior of a sailboat. While working on it, it was believed that he dropped a wrench, shorting the battery terminals. The resulting explosion was catastrophic.

I'll never forget looking at the x-rays in the hospital Imaging Department one night. There wasn't a single major long bone that wasn't fractured. I can't recall if he ultimately survived; he was alive when the helicopter took him to the regional trauma center.

Battery box "adding to the shrapnel?" No, that's not the concern. The pure blunt force trauma, not to mention the acid, is devastating; anything that contains it is desirable. Of course, those el cheapo battery boxes that most folks have on their outboard runabouts aren't what we're talking about. The battery boxes on Kingfisher are extremely heavy polyethylene with welded seams; I could use them to block up my truck.

Click to expand...

Wrenches used on submarine batteries were said to be made of "brass" from the 60 and before plus they were not long enough to reach between battery terminals.

Riverguy said:

A six-cell battery is a terribly unreliable configuration, because the MTBF of the battery (or 'six-cell RAID-0 array') is exactly one-sixth of the MTBF of a single cell.

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The MTBF comparison is true, but, to those who don't understand the nuances of what the MTBF of a system represents, it can be very, very, very easily misunderstood. For example, it isn't the case that a 6 battery/cell system is likely to last 1/6th as long as a 1 battery/cell system, even when the system is dependent upon all of them working.

I've never measured in my boats or around the docks, but in my observation, this isn't close to true. And, I suspect most others have similar experience. And, this is for good reason.

The MTBF of a system doesn't consider the initial period of newness related failure or the later period of age related failure, only the level, middle portion of the "bathtub curve".

And, it doesn't consider other-than-independent failure or most failures resulting from external influences. In the case of battery banks/cells, such excluded failures include those related to over-charging, discharging too much, overheating, failure to water the cells as required or to do so with other than pure water, overloading, crawling/walking on batteries/cells, movement and mechanical loading from boat movement, and/or externally shorting terminals. These types of failures affect all batteries in the same way, rather than independently, so the risk of failure shouldn't be multiplied out as is the case with the MTBF calculation referenced here.

In practice this MTBF comparison is only meaningful for failures during the batteries normal lifetime and under normal, compliant use. It isn't meaningful w.r.t. the impact of how we use them beyond this, how we maintain them, the conditions under which they are used, or young or old age.

In other words, the MTBF number only describes the affected lifetime if they die during their normal lifetime just for existing, and not with any other out-of-spec or external contributing factors. And, in the case of boat batteries -- there are usually a ton of other factors that are, in many installations, dominating.

Also, just for unnecessary and meaningless technical correctness, MTBF applies to a bank of batteries -- but not a battery consisting of multiple cells, in which case the applicable metric is called Mean Time To Failure (MTTF). One uses MTBF in cases where the failure can be fixed and MTTF, otherwise.