This is WHY you should use a BMS of some sort....

Korishan

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Soooooo, came across this little gem today. He has 2 Tesla packs in this little cart. He isn't using a bms while charging it, AND using a dumb charger, apparently.



Korishan@YT said:
Ok, so reading a bit further, someone mentioned3:14. So I looked, and before3:13you can see a wire on the floor running up the side of the car and into the carriage. At3:14the wire is no longer there. Also, the guy jumped position as the video was edited right there, removing a few seconds worth.

Sooooo, the batteries were being charged WITHOUT a bms, and the cells were most likely OVERCHARGED causing the fire.?


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You can see there was a cable, then it disappeared. So we know what happened here.

ALWAYS use some sort of BMS while charging Lithium based cells, especially when more than 1s! If the charger only has 2 wires, it's a dumb charger and doesn't know the state of charge of the individual packs in series. This is HIGHLY dangerous and irresponsible.
 
Why on earth would you charge the worlds most dangerous battery without a BMS? I say the worlds most dangerous battery - because they are essentially miniature rockets. No other cylindrical lithium battery is built without a CID. Even pouch cells are not going to take off like missiles. For this reason alone - I would not own a Tesla pack, let alone charge one improperly.
 
That was very scary to watch. With 18650 cells I always use a balance charger to charge, I never take chances. They also have a BMS but they can always fail. I don't think they knew the dangers of charging lithium without somehow monitoring for cell voltage.

I only had one lithium fire it was a 26650 lifepo4 cylindrical cell that I shorted out. You need to pour water on the cell quickly, not to put it out but to keep the surrounding cells from catching on fire. Once the fire starts nothing will put it out, but if you can prevent other cells from cooking off, the cell on fire will eventually burn out. Once all the cells catch on fire, you get what is on the video. The fire extinguisheris useless for this type of fire, it won't keep the other cells cool. The fire department in the video by using water prevented all the remaining cells from cooking off and let the fire itself burn it self out.

But one thing I never understand is why these cells catch on fire when overcharged? I always thought they were suppose to vent? Maybe one overheated caught wiring on fireand started the chain reaction. I notice the cells didnt have any shrinkwrap on them, they were bare metal. Maybe a wire shorted out.
 
The out gassing can catch fire through flash point. It's soo hot when it's venting it flash ignites. When that happens, it just goes. The other thing that can cause it is when the cell ruptures, the metal tearing could create sparks and enough to ignite the out gassing as well.

This is, of course, a best guess. I am no fire marshall nor am I a fire expert. Though, I do love a good bon fire ;)
 
jonyjoe505 said:
I only had one lithium fire it was a 26650 lifepo4 cylindrical cell that I shorted out.

lifepo4 can catch fire?? I thought that was the main advantage over lithium-ion, they will double size etc.. but never catch fire.
I was actually considering giving up on li-ion at some point for the safe and almost maintenance freelifepo4 (bms still needed ofc)
 
raccooon said:
jonyjoe505 said:
I only had one lithium fire it was a 26650 lifepo4 cylindrical cell that I shorted out.

lifepo4 can catch fire?? I thought that was the main advantage over lithium-ion, they will double size etc.. but never catch fire.
I was actually considering giving up on li-ion at some point for the safe and almost maintenance freelifepo4 (bms still needed ofc)

Yes. Yes it can. It is however far more tolerant over charging and over discharging.
 
It is well-established that charging to 4.2V per cell is not good, as it only adds a bout 1.17th the amount of possible range compared to charging to 4.1V per cell but...it might double the life of an expensive battery pack.

The Chevy Volt and the various Tesla cars have outstanding warranties on the batteries, because that was a major concern of the potential customers. They charge to 4.05V

Its good to use a high-quality BMS, but the battery pack builders who do NOT use a BMS oftencharge to only 4.0V per cell. If one cell is slightly out of balance, it is still below 4.2V (a 2S series string with a 4.0V cell-group and a 4.3V cell-group will average out to 4.15V).

I am looking for a BMS that will balance all the cells at 4.1V, and I haven't found one yet...
 
All decent BMS systems can have set balance points. Orion, Batrium or any other nice looking one can do that.
 
Hi chaps

Carl, from Rich Rebuilds

no idea why I registered here to say this but.... the lead is disconnected from the wall with his other hand and the other when he leans other, the cut is nothing more but a pace improvement :)
 
princeofthehouse said:
Hi chaps

Carl, from Rich Rebuilds

no idea why I registered here to say this but.... the lead is disconnected from the wall with his other hand and the other when he leans other, the cut is nothing more but a pace improvement :)

What type of charger was it ?
 
Sean said:
princeofthehouse said:
Hi chaps

Carl, from Rich Rebuilds

no idea why I registered here to say this but.... the lead is disconnected from the wall with his other hand and the other when he leans other, the cut is nothing more but a pace improvement :)

What type of charger was it ?
giphy.gif
 
princeofthehouse said:
Hi chaps

Carl, from Rich Rebuilds

no idea why I registered here to say this but.... the lead is disconnected from the wall with his other hand and the other when he leans other, the cut is nothing more but a pace improvement :)

"the cut is nothing more but a pace improvement" Then why are there multiple other angles where the video shows "nothing" until the cart is being shoved past it? This is one of the reasons why it seems odd. There's only a few frames missing, from what I can tell, maybe 1 seconds worth. It just looks odd. If it was a pace saving issue, then the other parts of the video would of been left out as all the other clips with nothing happening in them would shrink the video by almost a minute. Even the guys who are watching the various replies don't say anything during some of these cuts.
 
princeofthehouse said:
Sean said:
princeofthehouse said:
Hi chaps

Carl, from Rich Rebuilds

no idea why I registered here to say this but.... the lead is disconnected from the wall with his other hand and the other when he leans other, the cut is nothing more but a pace improvement :)

What type of charger was it ?
giphy.gif

Is this why the video was cut? Because it showed the "special" charger in the clip? If so, why make it a big deal? Couldn't you just have "blurred" out the charger instead of cutting the clip? It would of made a WHOLE lot more sense.
 
Wait.

Not only is he not using a BMS, he's charging a lithium ion battery pack with a "48V" lead acid battery charger.

This probably was cause by the golf cart type charger, as it was "48v"

12s * 4.2v/cell = 50.4v max charge voltage.

No problem here, right? No! 48V is the nominal voltage of a 4S 12V lead acid battery system!

The problem is that, Rich, the guy known for being smart and knowledgeable, didn't think much about battery chemistry, as 12V is their nominal voltage, and they can easily reach a max charging voltage of 14,4V, or even 15V under bad conditions.

So the "48v" charger is actually putting out up to 60V!

57.6v / 12cells = 4.8v per cell (up to 5v if 60v charger). Oops!

So of course the whole pack cooked off. It was massively, massively, massively overcharged.
 
Problem with these guys is that they didn't use a proper method to put out the fire:

Once a cell goes up in flames, it will produce it's own oxidizer, so there's no way to put it out, there is no magic substance to put out a li-ion battery fire. The goal then is to prevent other (adjacent) cells from catching fire, which will happen once they get hot enough. So, the point is to lower the temperature as fast as possible. Best way to do it, is by dumping large amounts of water. That's what Tesla also says, that's what the fire department would do.

It may seem that water would short-circuit the battery or something, but on a per-cell level, the voltage of a single cell is not enough to create a short-circuit. If you have a battery that's over 100V then this would cause a short circuit, however that will be at the end terminals, a couple of fuses will pop and that's it!
That said, it would be ideal to isolate the battery from the rest of the electronics, since you wouldn't want water all over inverters and stuff that would probably be connected to mains.

Bottom line is, that if you have a 24V battery and a couple of cells turn to fireworks, your best bet is to get a water hose and drown the whole block, just keep the water away from inverters and other electronics. Once the damaged cells burn up, you'll most likely find that all the other cells remain undamaged, since they will not short-circuit by water, let alone they tend to be sealed.

A great idea for powerwalls would be to construct a metal tank with individual compartments for each of the S-modules; that way, you could fill whichever needed, in case of emergency.
 
make sure you subscribed and you will get a answer to some of this today, including a unedited part of the clip that makes you so paranoid :D lol
 
princeofthehouse said:
make sure you subscribed and you will get a answer to some of this today, including a unedited part of the clip that makes you so paranoid :D lol

It's not that I'm paranoid, it's that I like transparency or at least a bit of explanation up front about why something does not look right. Then again, it could of all been a click bait drive viewers/subs to the channel ploy.
I won't be subbed, but I'll check to see if the video is available. Perhaps you can save us the hassle and post a link here when it's ready
 
Korishan said:
princeofthehouse said:
make sure you subscribed and you will get a answer to some of this today, including a unedited part of the clip that makes you so paranoid :D lol

It's not that I'm paranoid, it's that I like transparency or at least a bit of explanation up front about why something does not look right. Then again, it could of all been a click bait drive viewers/subs to the channel ploy.
I won't be subbed, but I'll check to see if the video is available. Perhaps you can save us the hassle and post a link here when it's ready

as you wish. anywayTesla Battery Fire, What Went Wrong?
 
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