Somebody doesn't understand how to properly manipulate
statistics to get them to show the results You want ..........

EVs are less than 1% of the registered Vehicles in the US.

An EV Fire is a deadly serious event.

When a regular ICE-Engine Car or Truck,
which is probably going to be over ~20-years-old,
catches Fire,
which is generally caused by really-really poor, or non-existent, routine-maintenance,
and not because of the inherent design, or materials of construction,
you just keep everybody back a safe distance until it goes out.

A Fire-Truck will normally extinguish the Fire in mere SECONDS of arriving on the scene.
That's not the way things go with an EV Fire.

Back in the day,
when there were Steam-Powered-Cars, and Lead-Acid-Battery-Electric-Cars,
it was not unheard of to have a Boiler-Explosion, kill several people.

Dangerous designs eventually get replaced with some sort of safer technology.
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Back to the original question: Try to recover cells? It ain't worth the risk. I'm a firefighter and have responded to several Li-ion battery fires (various chemistries). One of the things I've learned is that the "incident" event may not coincide with the "abuse" event. Abuse can be temperature, overdischarge, overcharge, physical, etc. You might recover the cell(s) but down the line a future discharge/charge cycle might result in overheating and resultant thermal runaway. If you want to rebuilt your battery pack, purchase some quality cells and rebuild it. Just my 2 cents.

 

If you end up dealing with a fire caused by a high voltage battery pack, remember that a stream of water can serve as a wire, which might be bad for your health. Obviously this isn't a concern if the pack has only a few cells.

 

If you end up dealing with a fire caused by a high voltage battery pack, remember that a stream of water can serve as a wire, which might be bad for your health. Obviously this isn't a concern if the pack has only a few cells.

I don't think there is much danger of electric shock if aren't sticking your hands into the battery. The water, which may or may not be a good conductor depending on its mineral content is only going to short out the battery—There is no way for you to complete a circuit.

Replace the water with a fat copper wire, how does the one wire conduct anything to you?

 

I have recovered hundreds of Li-ion cells where the voltage has dropped below 1V but higher than .3V. As per the thread slow constant current charging and heat monitoring is the key.

Yepp, perhaps. BUT, the problem itself is the copper bridges forming between anode and cathode creating a full short inside the stomack. And then only is needed to shake a cell or just think bad about it, and the firing is triggered where only the Fire Rescue vehicle may help. So, these even successfully recovered elements still are dangerous for some first hundred cycles, especially near the maximum allowance voltage and temperature.

 

Yepp, perhaps. BUT, the problem itself is the copper bridges forming between anode and cathode creating a full short inside the stomack. And then only is needed to shake a cell or just think bad about it, and the firing is triggered where only the Fire Rescue vehicle may help. So, these even successfully recovered elements still are dangerous for some first hundred cycles, especially near the maximum allowance voltage and temperature.

But according to research quoted by BigClive earlier in this thread, those copper bridges only form if the cell is reverse charged.

 

I don't think there is much danger of electric shock if aren't sticking your hands into the battery. The water, which may or may not be a good conductor depending on its mineral content is only going to short out the battery—There is no way for you to complete a circuit.

Replace the water with a fat copper wire, how does the one wire conduct anything to you?

I don't have any personal expertise with this, other than having been hit with 240V when pouring a bucket of water into a metal tank sitting on the ground with a submersible pump that had a nick in the insulation The potential for a firefighter getting electric shock is mentioned in many places (a few listed below), but sometimes in combination with the risk of reignition, a completely separate issue.

I agree that it would take a few things to happen for you to become part of the circuit, such as a continuous stream of water from one battery terminal to the ground and another stream from the other battery terminal to you. But that doesn't seem too far fetched when flooding a car with water.

• https://www.firerescue1.com/electri...ight-electric-vehicle-fires-EvBZIyP7EA78muwc/
• https://www.kmbc.com/article/firefighters-learn-fight-lithium-ion-battery-fires/45770550
• https://www.ntsb.gov/safety/safety-studies/Pages/HWY19SP002.aspx
• https://www.onlinesafetytrainer.com...w-tips-for-first-responders-and-firefighters/

 

I agree that it would take a few things to happen for you to become part of the circuit, such as a continuous stream of water from one battery terminal to the ground and another stream from the other battery terminal to you. But that doesn't seem too far fetched when flooding a car with water.

A circuit requires that there be a conductive path from the positive terminal to the negative—without this, current can’t flow.

If the battery is being flooded, the short distance between the two terminals (relative to the path to the hose wielder) would be much lower resistance.

If somehow:

the two terminals were physically isolated from each other in a watertight way, but not to the outside, and;

one was in a puddle of water in which the potential victim was standing with soaked and non-waterproof shoes, and:

the hose hand and hose were very wet and there were no gloves (or wet, non-waterproof gloves) involved, and;

the battery were somehow still intact enough to produce a high voltage—

then it might be possible to feel the current but it would almost certainly be little current due to the very high resistance path.

But, it’s possible that given no precautions at all, and bad luck, it could be a real problem.

 

A circuit requires that there be a conductive path from the positive terminal to the negative—without this, current can’t flow.

If the battery is being flooded, the short distance between the two terminals (relative to the path to the hose wielder) would be much lower resistance.

If somehow:

the two terminals were physically isolated from each other in a watertight way, but not to the outside, and;

one was in a puddle of water in which the potential victim was standing with soaked and non-waterproof shoes, and:

the hose hand and hose were very wet and there were no gloves (or wet, non-waterproof gloves) involved, and;

the battery were somehow still intact enough to produce a high voltage—

then it might be possible to feel the current but it would almost certainly be little current due to the very high resistance path.

But, it’s possible that given no precautions at all, and bad luck, it could be a real problem.

I understand what you are saying. But while a puddle of water connecting the two terminals would surely conduct some current, I think it is likely that the battery could supply that much current while maintaining nearly its full voltage for quite some time. So every other complete circuit between the terminals would also conduct based on that voltage and the resistance of each path. If just a few hundred mA make it through the stream of water to you...

When I got hit with 240Vac, the submersible pump with bad insulation was in a metal tank that was sitting on the ground, a more direct circuit than through me, my rubber boots and the plastic bucket. Nonetheless, I got hit. The current path through the water and metal tank to ground surely carried a lot more current than the path through me. But judging by the fact that it didn't flip the (non-GFCI) breaker, I'm guessing that it was still getting near 240V even while supplying the current to multiple paths. Unless one of the paths conducts enough current to pull the voltage down to a safe level, I think it is still a significant risk.

 

Haha interesting thread and has been lots of fun reading the arguments and tangents.

As an update of sorts, as often threads like this start (especially in IT) and the owner ghosts when they have their answer.

I charged two packs to 3.2V, one cell at a time and monitored temps, nothing out of the ordinary. Then put them on the normal charger which picked up happily and did its job.

One of the packs (5S2P) seems to be fully recovered, lasts as long as it always did and doesn't show any voltage drop after time.

The other pack (5S1P) was "usable" but never really recovered. It charged to the charger saying it was ready, but immediately dropped in voltage, and kept dropping. It bottoms out higher than 16, so devices can still recognise it as being usable and it'll spin my impact driver, but not for long. So it's effectively dead and I'll rebuild that one...eventually...probably...(I probably won't get around to it).

However don't let this distract from the digression and other conversation.

 

Yepp, perhaps. BUT, the problem itself is the copper bridges forming between anode and cathode creating a full short inside the stomack. And then only is needed to shake a cell or just think bad about it, and the firing is triggered where only the Fire Rescue vehicle may help. So, these even successfully recovered elements still are dangerous for some first hundred cycles, especially near the maximum allowance voltage and temperature.

both good points, some further thought...if a series cell has reduced capacity and the pack is heavily discharged, is the cell potentially reverse charged thus generating the internal shorts? seems logical but in practice I haven't seen many failed packs with only 1 cell shorted.

 

It only takes ONE exception to the rule.
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both good points, some further thought...if a series cell has reduced capacity and the pack is heavily discharged, is the cell potentially reverse charged thus generating the internal shorts? seems logical but in practice I haven't seen many failed packs with only 1 cell shorted.

The BMS should prevent that. When any one cell has discharged to the minimum it would disconnect the battery from the load.

 

The BMS should prevent that. When any one cell has discharged to the minimum it would disconnect the battery from the load.

But not from any other cells that it is wired in series with. But that could be arranged with MOSFETs, at a cost.

 

But not from any other cells that it is wired in series with. But that could be arranged with MOSFETs, at a cost.

Disconnecting the load would mean no more discharge current from the battery. The cells would still be in series but there would be no current.