Might have damaged my battery pack! ;(

[harryS]

Good for you, Teslabike. Now your next job is proper disposal. Can't have a garbage truck catch on fire. I've read that RC hobbyists commonly would put a bad cell in a bucket of salt water. That will discharge it thru electrolysis and make it safe. However, with a gash down the side, I don't know.

Many years ago, my buddy disposed of a cube of elemental lithium in the dorm toilet. He was worried it would catch fire siting on his desk, after he stole it from the lab. It started releasing hydrogen and got so hot the gas ignited and threw up a wall of fire. I kicked the flush handle and as it went down, a one last explosion threw the water out at us. Good thing it was a dorm, with giant sewer pipes,

 

[Mr. Coffee]

Where to take something like that? The fire department? What should someone do in this situation? "Put it outside" could also be a disaster and cause a wildfire, depending on the region. Thoughts? If one doesn't have a fire pit handy in the backyard, what to do? Maybe put it in the BBQ grill?

Actually it gets complicated fast...

If you have a situation where you have a damaged e-bike battery, I'd recommend calling your local fire department for advice on how to get rid of it. I'd also follow up with calls to your local transfer station (usually they have some way of handling battery disposal, but may not be able to take a possibly damaged and dangerous battery) and the bike shop where you purchased the battery. Be prepared to not get very much help.

Short term, I'd get a beefy metal pail from the hardware store and place the battery in the pail and keep the whole shebang well away from anything flammable. Ideally on a concrete or gravel surface.

Longer term, if I was going to dispose of one at home (which I wouldn't recommend unless you can't get any help anywhere else) would be to bury the defective battery at least 3 feet underground. Since a Lithium battery doesn't have very much toxic stuff in it I doubt you'd need to be excessively worried about polluting groundwater, and 3 feet would be more than enough insulation for preventing even a fairly major thermal runaway from starting a fire.

 

[TeslaBike]

Good for you, Teslabike. Now your next job is proper disposal. Can't have a garbage truck catch on fire. I've read that RC hobbyists commonly would put a bad cell in a bucket of salt water. That will discharge it thru electrolysis and make it safe. However, with a gash down the side, I don't know.

Many years ago, my buddy disposed of a cube of elemental lithium in the dorm toilet. He was worried it would catch fire siting on his desk, after he stole it from the lab. It started releasing hydrogen and got so hot the gas ignited and threw up a wall of fire. I kicked the flush handle and as it went down, a one last explosion threw the water out at us. Good thing it was a dorm, with giant sewer pipes,

Here in Portugal we have battery bins all over the place that accept lithium cells aswell. I might try to leave it in salt water for a couple of days and see what happens.

Cool story to tell the kids
I had a "similar" experience with sodium, I was 14 in a chemestry class and I was 2 feet away watching the bowl of water with the sodium in it forming into a burning ball untill... POOF. I got hit in the eye with a couple sodium bbs that continued to react in contact with my eye. Not a fun ending. As they were cleansing my eye at the hospital, I though, what a cool metal this is, I wanna see more of that xD

 

[Off road all day]

If one blew how stable are the rest, at least the way i look at it not worth the risk. You may replace the cell, which is easy, and never have a prob. but if the pack blows your in a whole world of hurt.
I say this because i saw the results of a 12 volt lead acid car battery exploding. I was in motor vehicle repair and it happened next door at heavy duty. This paled in comparison to what a lithium explosion can do.
I may be a worry wart but better safe than sorry.
A friend and a guy i knew died in explosions that where not suppose to happen, so i'm probable a little over cautious on this one.

 

[harryS]

If one blew how stable are the rest, at least the way i look at it not worth the risk. You may replace the cell, which is easy, and never have a prob. but if the pack blows your in a whole world of hurt.

This is a good point, and in line with the original title. It could have been damaged if any of the cell groups got discharged below 2.5V by the incident. Tesla should check them with a meter before charging the battery.

 

[Alex M]

That being said, do you think it can still over heat or catch fire??

It already did overheat. And almost caught fire, hard to tell why it didn't. What happened was most likely an internal short inside this cell. The exterior casing was not the primary culprit but could've aggravated it, creating a tiny arc.

It sounds like you build this pack yourself - then it is possible that you mechanically damaged one cell in the process. Better get rid of this cell. I don't think that most factory packs are insulated inside, i.e. one cell from another. But they usually add plastic framing around the pack, to make it more stable.

 

[TeslaBike]

If one blew how stable are the rest, at least the way i look at it not worth the risk. You may replace the cell, which is easy, and never have a prob. but if the pack blows your in a whole world of hurt.

This is a good point, and in line with the original title. It could have been damaged if any of the cell groups got discharged below 2.5V by the incident. Tesla should check them with a meter before charging the battery.

Despite the short, after replacing the cell, I tested every row at 3.5V, just as they came. I´ll try to charge it tommorow, outdoors of course, and see what happens.

My pack is pretty much done, with BMS and all, but there is still time to solder some extra wires for Cell Logs. might be a good idea in this case?

It already did overheat. And almost caught fire, hard to tell why it didn't. What happened was most likely an internal short inside this cell. The exterior casing was not the primary culprit but could've aggravated it, creating a tiny arc.

Alex, the short wasn´t caused only by one cell. It would have not melted through the the case and box. It was between the Positive terminal of the pack and the negative side of that particular cell (wich was on the 13S row). It was a 54V short basicly.