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Old 04-02-2019, 11:17 AM   #41
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Would a heavy duty box like this contain that kind of blow?
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Old 04-02-2019, 01:24 PM   #42
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Use the box to contain the "blow-up", but vent it to get rid of the H2
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Old 04-02-2019, 02:48 PM   #43
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Yes, GLAD no injuries, and a good lesson for all.

Question: are sealed batteries any safer?
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Old 04-02-2019, 06:45 PM   #44
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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...
Start Typing Another Resume...love it!
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Old 04-03-2019, 07:13 AM   #45
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Question: are sealed batteries any safer?

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).

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Old 04-03-2019, 07:40 AM   #46
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Would a heavy duty box like this contain that kind of blow?

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.
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Old 04-03-2019, 07:58 AM   #47
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Start Typing Another Resume...love it!
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

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Old 04-03-2019, 09:35 AM   #48
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RIVERGUY thanks for the long summary. It reminds me of another reason why Iím a proponent of 2V batteries in series.
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Old 04-03-2019, 04:06 PM   #49
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Show and tell.

Actually a grp 24 starting batt that was in the boat for the thruster.
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Old 04-03-2019, 04:12 PM   #50
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Nice! That's a beauty. Hope nobody was hurt.
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Old 04-03-2019, 05:08 PM   #51
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Glad it turned out well, injury wise Ski. That blowed up real good...


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Old 04-03-2019, 09:39 PM   #52
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ROFLMAO! Good one, RTF!
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Old 04-03-2019, 09:59 PM   #53
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Blow'd up real good!!!
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Old 04-04-2019, 06:54 PM   #54
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Mean Time Between Failures; Battery RAID math?

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

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.
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Old 04-04-2019, 07:51 PM   #55
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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?
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Old 04-04-2019, 08:49 PM   #56
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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.
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Old 04-04-2019, 09:21 PM   #57
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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.
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Old 04-04-2019, 09:30 PM   #58
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Quote:
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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.
And Lithium is supposed to be dangerous.
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Old 04-04-2019, 09:43 PM   #59
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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.
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.
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Old 04-04-2019, 10:34 PM   #60
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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.
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.
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