House burned down

[Zwy]

Not a fan, used it for 4-5yrs... I think the K9 setup is better, I had a lot of issues with the cellmon network connections on my blockmon M8's.

I run the K9's and like the setup. Can always daisy chain in more for expansion. My Batrium has worked flawless except for the firmware update that reset all my settings which tripped the shunt trip.

I thought about using Batrium for the shop system but the cost didn't agree with the low budget build I'm doing.

 

[Brett V]

The fuses and contactors are on the positives in my setup.

View attachment 212615

I would swap the position of the contactor and fuse.

 

[robbob2112]

You lost your NUT, or you are a nut, or something like that ... Oh the humanity... soon cats and dogs will be sleeping together.

 

[SilverbackMP]

I would swap the position of the contactor and fuse.

Contactor needs to be in umm contact in order to function. If the fuse blows, then the contactor is pointless. REC manuals and my (former) industrial electrician are in agreement on placement.

 

[SilverbackMP]

You lost your NUT, or you are a nut, or something like that ... Oh the humanity... soon cats and dogs will be sleeping together.


View attachment 212623

That battery was pulled to replace a cell and I had started taking off bits and bobs to get at it.

 

[haraldt1]

hello, I came across you by chance while searching in a German forum, first of all, it's good that nothing happened to anyone. but from my point of view it's absolute nonsense what the fire expert here wants to have found as a fault.
if it happened at night with low currents, where did the high currents come from to blow the fuse? there must have been a short circuit on the inverter or the wiring. In addition, the BMS should have switched off. So if it was not a combination of several faults at the same time, then in my view the fuse can be ruled out. I would rather assume a short circuit due to the lack of insulation between the cells as far as I have seen. A fuse can never cause a fire without a significant load.

Sorry for my bad English ;-)

 

[upnorthandpersonal]

A fuse can never cause a fire without a significant load.

If there is a short due to a failing inverter for instance, and the fuse is not able to quench the arc, it most definitely can start a fire. Whether that is the case here or not is undetermined, but you can't rule it out.

 

[robby]

I'm glad these EG4 indoor batteries have integrated fire suppression.

I would like to actually see this work in a real situation. Has EG4 or anyone else ever demonstrated this being used to extinguish a fire inside a battery pack? I

 

[Mattb4]

If there is a short due to a failing inverter for instance, and the fuse is not able to quench the arc, it most definitely can start a fire. Whether that is the case here or not is undetermined, but you can't rule it out.

That's why I keep my fuses separate from the dynamite. Darn things are always causing a problem. Maybe the fuses need a special protective box?

Sorry about the humor.

 

[upnorthandpersonal]

Maybe the fuses need a special protective box?

You joke, but just look online to find images of melted/burnt fuse holders.

 

[Yurtdweller]

I have not read the entire thread. Apologies. My question is, do we know, did the arc start a fire that spread to the batteries? Or did incoming power overload the batteries somehow, and then the battery cells actually initiated the fire? I ask because I travel in a yurt, therefore I have my LiFePo4 cells inside my yurt with me. I cannot have an outbuilding for various reasons. Since the fire started at night, the solar was obviously not feeding excessive power into the system. This fault must have come from the battery outputting excessive power, for some reason, or from an incoming power source feeding massive amps into the system? I have four 12v packs of LiFePo4 cells (Lf280k). Each pack is individually mega-fused (125 amps) before connecting through a Lynx PowerIn bus. Each pack is BMS limited to 100 amps. I am curious as to how large of an arc can be initiated by 100 amps @ 12v, and whether it could arc across that fuse gap? I cannot conceive of any situation that could cause that battery to output enough power to jump such a gap, and since I have no incoming power besides 60 amps from my charge controller, I cannot see any chance of incoming power causing such a situation, either. But I want to try to understand what caused the situation of this fire, just in case I've overlooked something.

 

[upnorthandpersonal]

do we know, did the arc start a fire that spread to the batteries? Or did incoming power overload the batteries somehow, and then the battery cells actually initiated the fire?

We don't know anything, that's why we're 17 pages into speculation.

 

[Zwy]

hello, I came across you by chance while searching in a German forum, first of all, it's good that nothing happened to anyone. but from my point of view it's absolute nonsense what the fire expert here wants to have found as a fault.
if it happened at night with low currents, where did the high currents come from to blow the fuse? there must have been a short circuit on the inverter or the wiring. In addition, the BMS should have switched off. So if it was not a combination of several faults at the same time, then in my view the fuse can be ruled out. I would rather assume a short circuit due to the lack of insulation between the cells as far as I have seen. A fuse can never cause a fire without a significant load.

Sorry for my bad English ;-)

If a cell shorts internally, it will draw current from the other batteries in the bank. External loads can be non existent but the failed cell would cause a tremendous load.

 

[MattiFin]

If a cell shorts internally, it will draw current from the other batteries in the bank. External loads can be non existent but the failed cell would cause a tremendous load.

Also there are no quarantees that the cell shorts to solid zero ohms. It could as well short partially and draw only 200A.
Over time 6 parallel strings would dump nearly 1800Ah and 6kWh of energy to that poor cell. Enough energy to make the cell glow red.

Recommendation for String level contactor disconnect seem like smart move.

 

[SeaGal]

I cannot conceive of any situation that could cause that battery to output enough power to jump such a gap,

@Zwy's posting ^^^^ (post#333) explains a situation that could cause that battery to output enough power.

 

[Shimmy]

The OP did the right setup but used a fuse between batteries that was not a Class T. I'm quite certain this is the cause of the fire.

The fuse provided an ignition source for sure; it is also likely that it made the fire more difficult to put out.

But in terms of a roof-cause analysis you either need to say cell failures are inevitable, and the lack of BMS string isolation was the root cause, or you say that the cell failure was an extraordinary event and the root cause.

Moreover, with cell failure you have what I understand to be an anomaly in a cell failing shorted to the point that other cells enter thermal runaway. For a cell to fail shorted are we looking at things like dendrites that escalate a small, high-resistance short into a dead short, or some catastrophic event that creates a dead short?

 

[PotusGobbleBottom]

Also there are no quarantees that the cell shorts to solid zero ohms. It could as well short partially and draw only 200A.
Over time 6 parallel strings would dump nearly 1800Ah and 6kWh of energy to that poor cell. Enough energy to make the cell glow red.

Recommendation for String level contactor disconnect seem like smart move.

It would only be a 3. 2v drop and the other 15 cells would soak that up in mere seconds across the 15s . We are talking about 0.225v gain across the 15s remaining.... if the other cells were at rest, fully charged, at 3.45 they might not even be high cell voltage disconnect.
I seriously doubt we are talking about more than 100 amps for less than a minute. Certainly nothing to blow a fuse over.

 

[MattiFin]

It would only be a 3. 2v drop and the other 15 cells would soak that up in mere seconds across the 15s . We are talking about 0.225v gain across the 15s remaining.... if the other cells were at rest, fully charged, at 3.45 they might not even be high cell voltage disconnect.

Very good point. Current dumping from other cells would be a major problem only on battery banks with cells in parallel.
Also fuses should have no problem disconnecting the string with one battery failed to zero ohms as currents involved are only about 1/15 of invidual cell short circuit current. (3.3v voltage difference between the strings but ~15x series resistance of invidual cell)
Fuse also needs to break only 3 volt potential, again very easy task for even something less capable than class-T.

 

[Shimmy]

It would only be a 3. 2v drop and the other 15 cells would soak that up in mere seconds across the 15s . We are talking about 0.225v gain across the 15s remaining.... if the other cells were at rest, fully charged, at 3.45 they might not even be high cell voltage disconnect.
I seriously doubt we are talking about more than 100 amps for less than a minute. Certainly nothing to blow a fuse over.

So in an inverter short scenario how does the battery not get disconnected from the inverter... and why is the fuse considered the ignition source? The fuses are significantly less likely to see currents in excess of their interrupting rating as currents are shared and external resistance comes into play.

For an unmaintained system I get how there could he multiple failures that went unnoticed, but that doesn't seem to be the case here.

 

[PotusGobbleBottom]

I Got a 6s 20Ah lipo battery with one cell at 0. Should I charge it?
Or should I put it in parallel with a 6s and see what happens? Kidding. 6s is very different than 15-16s