Lithium Battery Fire Hazard... Explain?

[GrowleyMonster]

Yeah, I know... catastrophes are very rare, but since they have happened, (and some folks have been struck by lightning and one lady even got hit by a meteorite and some folks win the powerball) I was hoping someone knowledgeable could explain how and why this does or can or could rarely happen. Is it simply too much current into or out of the batteries? A bad cell? I can see how a small heat problem could quickly become a conflagration, but how does it start in the first place, and how can one ensure that it never happens to him?

[senormechanico]

Look up youtube videos of people putting a dead short on lithium iron phosphate (LiFePo4) cells with jumper cables, shooting them with a .45 etc.
Vapor, no fire.
Lithium COBALT, different story (Boeing Dreamliner).

[dannc]

Boats have sunk because of plain ol' lead acid batteries...

Later,
Dan

[Muckle Flugga]

Originally Posted by senormechanico

Look up youtube videos of people putting a dead short on lithium iron phosphate (LiFePo4) cells with jumper cables, shooting them with a .45 etc.
Vapor, no fire.
Lithium COBALT, different story (Boeing Dreamliner).

[Edit]
Sorry I misread your post previously. I thought you were speaking of generic or standard Lithium ION, but you meant Lithium Iron phosphate, which are indeed much safer than Generic of standard LI ION. With regard to the latter: overcharging lithium ion batteries can cause them to explode like a POWERFUL BOMB> this has happened to me with a Li Ion for a dive light, a bit bigger than a D cell. Faulty charger from China caused it suddenly to explode like a grenade. After the initial violent explosion with flames, it filled the boat with black smoke and soot, and even though I hit it with a CO2 within 3 seconds, it burned 7 deep black marks through the varnish, charring the veneer to destruction below!

In three seconds.

My understanding is they must be charged with an ever decreasing current strictly regulated, which if off even by a small amount can cause them to overheat and boil (yes I said boil), and cause a chain reaction which results EXTREMELY RAPIDLY in a sudden and violent and extremely HOT explosion. Of course this means charge failure is likely the cause… but charge regulator failure is not unheard of and indeed not all that uncommon in my experience.

For this reason I would not wish to have standard LI ION batteries in a main bank on my boat.

Why Some Lithium-Ion Batteries Explode

[GrowleyMonster]

So for the truly cautious over-engineering type, a temp sensor and a high temp shutdown relay might be a worthwhile addition to a system? Would that catch it in time? And yeah I gotcha about the cheap Chinese charger. Reminds me I need to address this issue with my ebike battery and its Chinese charger.