diy solar

diy solar

EG4 3000 EHV-48 fire. Been running a 12 panel system with 2 EG4-lifepower batteries and the EG4 3000 EHV-48. Added the battery rack and 3rd battery

Even if they have the gauge correct, it sounds like the insulation is wrong.

Also, what happened to the over current protection? If the inverter shorted the 48v DC bus, the breakers on each battery should have tripped. What are they 100 amps each?
So a max sustained current of 300 amps. With a typical breaker trip curve I'd expect a shorted DC bus to pull 1000's of amps.

I wonder what the interrupt rating is on the EG4 battery breakers? It may be they aren't rated to interupt the high short circuit current that the cells can provide.
Gauge is #4, I think I will add an additional breaker to set. None of the battery breakers tripped and the cable away from the fire was not hot.
 
Sounds like the inverter shorted the battery side.

You have fuses on each battery, but I would say you needed to fuse the battery input of the inverter. That's why the wires burst into flames.
That is where my thinking is going and the only place the wires were close was going into the inverter. I will separate the wires and add a breaker then run the wires to the rack in conduit.
 
Gauge is #4,
4 AWG? That is part of the problem.

If there is a 100A fuse on each battery, the combined current without blowing the fuse is 200A or more. That is too much for a 4AWG wire.

1656215643637.png

It appears there was a combination of problems.

1) Something inside the inverter created a resistive short that drove the current up very high, but still below the trip point of the fuses and BMSs.
2) The 4 AWG wire became a heating element.
3) The most likely place the wires got the hotest was at one of the crimps or ring lugs. In this case, it was one of the two where the wires were connected to the inverter.

So.... we do not know what caused the original short, but I am starting to get a picture of why it evolved into a fire.

Edit: Added the following:
To correctly set this up, there should have been a 100A fuse where the two positive wires come together or the wire should have been large enough to handle 200A.
 
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4 AWG? That is part of the problem.

If there is a 100A fuse on each battery, the combined current without blowing the fuse is 200A or more. That is too much for a 4AWG wire.

View attachment 100124

It appears there was a combination of problems.

1) Something inside the inverter created a resistive short that drove the current up very high, but still below the trip point of the fuses and BMSs.
2) The 4 AWG wire became a heating element.
3) The most likely place the wires got the hotest was at one of the crimps or ring lugs. In this case, it was one of the two where the wires were connected to the inverter.

So.... we do not know what caused the original short, but I am starting to get a picture of why it evolved into a fire.

Edit: Added the following:
To correctly set this up, there should have been a 100A fuse where the two positive wires come together or the wire should have been large enough to handle 200A.
Looks like it needs a 100 amp fuse added to the system as the wire size doesn't look like it can go any bigger into the inverter. Still doesn't solve why it shorted.
 
Sounds like the inverter shorted the battery side.
You have fuses on each battery, but I would say you needed to fuse the battery input of the inverter. That's why the wires burst into flames.

Yeah, sounds very plausible.

And of course we are wired in a very similar way. Fuses at the batteries (and MCBs where the battery leads combine) but no over-current protection for the inverter input itself!

I have a spare fuse and holder, time to get it out methinks.
 
There is one photo showing resistor and maybe transistor smoked. (out of focus). That doesn't fit idea of undersize cable being the cause.
The battery wire insulation just kept burning, and reigniting after extinguished? Do you know if the entire cable was hot or not?
Questionable pedigree of the wire. How about cutting a piece of the insulation and testing its flammability, compare to the UL listed insulation you have.

I'm wondering if the electronics that popped put out a flame which ignited bad insulation.

FR4 PCB material is self-extinguishing. Googling that related to wire, only a couple of types as self-extinguishing. But in this case, after extinguishing the smoke or fumes were hot enough to reignite.
 
They are all Chinese inverters.
Yes but you have the Chinese products that are made for Chinese Domestic use and also end up being exported to third word countries because they cannot comply to any kind of Western Code and these have very low prices.

Then you have the one's that are made for export to First world countries and those are typically designed abroad and the BOM are picked by the designers to Pass the code in the intended countries.
Whats happening now is a lot of low end made for Domestic sale Chinese Inverters are making it into the American market.

Outside of Inverters, since 2020 Amazon has become flooded with these kinds of products in just about every category.
 
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3000w÷48v= 62.5 amps is what the inveter is capable of so it could be fused just above that. Two 48v/100ah batteries could deliver 200 amps (9600w) before tripping the battery breakers. I don't know if it would have saved you, but when you rebuild you may want to fuse each EG4 (or whatever you replace it with) according to the potential inverter output.
 
There is one photo showing resistor and maybe transistor smoked. (out of focus). That doesn't fit idea of undersize cable being the cause.
The battery wire insulation just kept burning, and reigniting after extinguished? Do you know if the entire cable was hot or not?
Questionable pedigree of the wire. How about cutting a piece of the insulation and testing its flammability, compare to the UL listed insulation you have.

I'm wondering if the electronics that popped put out a flame which ignited bad insulation.

FR4 PCB material is self-extinguishing. Googling that related to wire, only a couple of types as self-extinguishing. But in this case, after extinguishing the smoke or fumes were hot enough to reignite.
The cable lower down was not hot, only the burning area. The section inside that was smoked was at the opposite corner. Fans were blowing smoke down and out the bottom near the wires, I wondered if it was the plastic sleeve that the wires went through that was on fire and burning the wire insulation. Cable ends were not discolored where they had been inserted into the buss bar.
 
3000w÷48v= 62.5 amps is what the inveter is capable of so it could be fused just above that. Two 48v/100ah batteries could deliver 200 amps (9600w) before tripping the battery breakers. I don't know if it would have saved you, but when you rebuild you may want to fuse each EG4 (or whatever you replace it with) according to the potential inverter output.
For our use I could fuse it at 100 amps just before it goes into the inverter.
 
3000w÷48v= 62.5 amps is what the inveter is capable of so it could be fused just above that. Two 48v/100ah batteries could deliver 200 amps (9600w) before tripping the battery breakers. I don't know if it would have saved you, but when you rebuild you may want to fuse each EG4 (or whatever you replace it with) according to the potential inverter output.
Careful..... that is not the full calculation.

It is good that you used 48V. That is at the lower end of the LiFePO4 voltage range, but it is also where the current will be highest in order to provide the needed wattage.

The efficiency of the inverter must be factored in. For this inverter, I would use a 90% efficiency. So that makes it 62.5/.9= 69.4. (If there is a load surge it will briefly spike higher.

You never want to run a fuse at its trip point so the fuse should be 69.4A x 1.25 = 86.8A. For a class-t fuse, you *might* find a 90A fuse, but since there could be brief surges that exceed 3000W and class T is a fast-acting fuse, I would go to 100A.

Note: I have found that this calculation usually comes up with a number that is the same or lower than what the inverter manuals recommend.... consequently this would be the minimum size fuse. If the manual recommends a larger fuse, you should use it and make sure the wire after the fuse can handle it.

Note: Some of the posts have said to put a/the fuse at the inverter. I would not do that. I would put it at the point the two positive lines from the batteries come together. This ensures the wire is protected.
 
Here are a couple of resources you might want to review:


 
Even if they have the gauge correct, it sounds like the insulation is wrong.

Also, what happened to the over current protection? If the inverter shorted the 48v DC bus, the breakers on each battery should have tripped. What are they 100 amps each?
So a max sustained current of 300 amps. With a typical breaker trip curve I'd expect a shorted DC bus to pull 1000's of amps.

I wonder what the interrupt rating is on the EG4 battery breakers? It may be they aren't rated to interupt the high short circuit current that the cells can provide.
Exactly, which makes me think the battery cables were undersized or long or something was limiting the current to less than the SUM of the battery breakers. Apparently, he didn't have a main breaker/fuse on the battery wire coming into the inverter. That's a no-no! When current is divided between battery banks, their protection breakers may not be tripped. It's the main breaker/fuse ahead of the inverter that offers the protection in this case. The use of a DC Sub-panel for battery banks would seem prudent.
 
I like the same setup off of the Will Prowse videos. Is there anyone else who has this setup, I've read about other problems but never fires with EG4.
The inverter did not catch fire. The wire insulation did. The inverter probably popped a FET and he didn't have a fuse/CB between the battery bank and the inverter. He was relying on the breakers in the individual batteries. So I wouldn't blame this on the inverter. The wires were not well protected.
 
Without an annotated three-line diagram I am hesitant to speculate, but to me this sounds more like a ground fault than a dead short. More specifically a ground fault for your first fire and a dead short (via ground) for the second.
 
The inverter did not catch fire. The wire insulation did. The inverter probably popped a FET and he didn't have a fuse/CB between the battery bank and the inverter. He was relying on the breakers in the individual batteries. So I wouldn't blame this on the inverter. The wires were not well protected.
At this point, I think it's still most likely that the inverter failed and found the poor insulation/wire gauge/breaker combo that created the fire.

I think it's odd that the OP says the other end of these main battery cable were not hot at the other end. That detail makes me doubt my supposed failure cascade.
 
I think it's odd that the OP says the other end of these main battery cable were not hot at the other end. That detail makes me doubt my supposed failure cascade.
A poor connection at one end leading to the cascade?
 
Copper is a very good thermal conductor. If a poor connection overheats one end of a battery cable, it will be very hot for quite a few feet.
 
Copper is a very good thermal conductor. If a poor connection overheats one end of a battery cable, it will be very hot for quite a few feet.
For a fast fault (1s<t<10s) I have seen one end of a 2' cable be hot and the other just warm. It usually depends on which side of the cable termination was the source of heat.
 
Copper is a very good thermal conductor. If a poor connection overheats one end of a battery cable, it will be very hot for quite a few feet.
Good point. If the inverter failure caused the wire to overheat, the whole wire would heat simultaneously due to the current flowing from end to end. However, if there were a loose connection at the inverter. Say, maybe he torqued down on the insulation and not the bare wire by mistake, then the wire would get very hot but only at the inverter end where the bad connection was at. When the connection finally got so hot it caused a FET to pop. IMO, this is more likely than a random inverter failure for no reason.
 
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