ScropusGobbleBottom
Corn Pop was a bad dude.
Good point here as well 3v doesn't like to arcFuse also needs to break only 3 volt potential, again very easy task for even something less capable than class-T.
Good point here as well 3v doesn't like to arcFuse also needs to break only 3 volt potential, again very easy task for even something less capable than class-T.
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.
Because fire dept. Guy thinks that was the hottest spot. And that is usually where the fire originates. There is probably some truth to the location, tho, not necessarily the fuse.why is the fuse considered the ignition source?
I don't think the fuse is to blame. The OP reported that some of the cells had leaked and he had to replace them. Most likely some cells shorted.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.
I look at it this way, if the fuse had not melted and not created and arc, there would not have been a combustion source. I have had leaking LFP batteries before, but they did not self ignite. Yes the cells shorted, and that was what caused the fuse to melt. Shorts themselves cause current to flow but do not necessarily create combustion if a fuse does its job. I may be splitting hairs but from a risk management viewpoint I came to the conclusion a Class T fuse would have mitigated the risk of a short.I don't think the fuse is to blame.
It's a relay. Doesn't matter where in the circuit it is to operate. You shouldn't have anything between the positive of the battery and a class-t but as short as physically possible cable that's sized large enough to carry the current surge that will open the 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.
I believe it's a chicken/egg thing. We don't know that the fuse was the combustion source. The fuse could have blown because wires melted from the fire and shorted.I look at it this way, if the fuse had not melted and not created and arc, there would not have been a combustion source. I have had leaking LFP batteries before, but they did not self ignite. Yes the cells shorted, and that was what caused the fuse to melt. Shorts themselves cause current to flow but do not necessarily create combustion if a fuse does its job.
Meh, argue with REC. There’s verbiage besides the schematics but I can’t be arsed to look for it.It's a relay. Doesn't matter where in the circuit it is to operate. You shouldn't have anything between the positive of the battery and a class-t but as short as physically possible cable that's sized large enough to carry the current surge that will open the fuse.
One big difference between your setup and the OP is he was working at 48v verse 12v.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.
Yes, anything is possible. I am just going off what the OP said about the fuse melting and arcing. He did say that the fire inspector referred to that general area as the combustion source. My takeaway from this thread was the importance of Class T fuses in the right places to mitigate the consequences of a short in a cell or in wiring.The fuse could have blown because wires melted from the fire and shorted.
Yes, the fuse is to blame for the fire. The cause of the fuse failing is most like due to a cell shorting internally. Follow along with the rest of us.I don't think the fuse is to blame. The OP reported that some of the cells had leaked and he had to replace them. Most likely some cells shorted.
Yes, the fuse is to blame for the fire. The cause of the fuse failing is most like due to a cell shorting internally. Follow along with the rest of us.
Class T fuses only. If a Class T was used, and one cell shorted internally, all that would probably have occurred was the Class T fuse would blow, power would be cut off to the battery containing the bad cell. The cell may have vented but it would not have started a fire.
What part of anything I have written in this thread you don't understand? If you believe you don't need a Class T fuse for this application, then do as you desire. My posting is to possibly prevent someone from making a mistake that leads to catastrophic failure.
We don't know what cells were used, whether these were some sub grade cells, how the cells were cycled other than most likely the discharge was not high due to the large size of the bank.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?
Have you looked at the specs? Interrupt is similar to Class T, but I'm not certain how the Class J is constructed. According to what I have seen, the Class J has a time delay. That may be too long with a very large current flowing.What if you used a Class J fuse?
You don't know that. The fire inspector said so, but that's a convenient answer. Fuse can blow for many reasons. The reason that caused this fuse to blow could have also been the source of the fire.Yes, the fuse is to blame for the fire. The cause of the fuse failing is most like due to a cell shorting internally. Follow along with the rest of us.
I'm 99.999% certain it was the fuse.You don't know that. The fire inspector said so, but that's a convenient answer. Fuse can blow for many reasons. The reason that caused this fuse to blow could have also been the source of the fire.
What if you used a Class J fuse?
Where the hell's that coming from? I have class T fuses. That has nothing to do with anything.I'm 99.999% certain it was the fuse.
The 0.001% I'll leave up to you.
I will only add, if you don't think you need Class T fuses for this application and attempting to justify your position because you don't have Class T fuses installed, I can only wish you the best of luck.