Checkthisout
Solar Wizard
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This is why we need to know if the breaker is interrupting both positive and negative.
Shunt snapped and caused a fire🔥
- Thread starter nezjnr
- Start date
This is why we need to know if the breaker is interrupting both positive and negative.
robbob2112
Doing more research, mosty harmless
From what I can tell the wires out the bottom of the breaker are to the packs, the wires out the top are to the busbars and inverter. So shorting the way you desdribe should have popped the breaker
Positive and negative per breaker.
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Checkthisout
Solar Wizard
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To me it looks like the collapsed shelf held the batteries.
And hence the end bracket popping out would have allowed the wood to fall the pack was sitting on which means those cables were being yanked by the full weight of the FALLING pack onto the shelf end bracket. (About 1/16 wide steel without finished edges).
If each breaker is in fact a positive and negative then to me this is "case closed".
The positive and negative cable UNFUSED between the pack and breaker had their insulation cut by the shelf bracket and both came into contact with the shelf bracket and shorted out which led the massive heat and ensuing fire.
The breaker did not pop because the wires shorted between the pack and breaker, as Robby pointed out.
Sorry that happened OP. Some serious time and cashola invested in that setup.
OffGridForGood
Catch, make or grow everything you can.
Why are the breakers 3P?
hwy17
Anti-Solar Enthusiast
Probably just a Chinese breaker that is "dual rated" for DC but more commonly used on 3 phase AC.
Personally I don't like DC breakers period and I won't use them in my DIY builds.
OffGridForGood
Catch, make or grow everything you can.
China also make 2P breakers.
So, why did the OP use 3P breakers?
I also wonder what amperage they are rated for.
I use DC rated breakers, but I also put fuses on all the critical circuits, I feel fuses are more reliable.
Breakers make maintenance and tinkering easier.
Checkthisout
Solar Wizard
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As Robby pointed out the breakers all popped as they should have except for the one that we believe had a short before its input.
OffGridForGood
Catch, make or grow everything you can.
Checking over my own system today,
It was a good day for this, solar was excellent and the PV was over 9kW for several hours.
I figured, well lets try a few things and 'see what happens'
First up, I checked how the incoming PV power was being shared between all the packs - checked out nearly equal, 168A incoming, approx 27A on each of 7 packs.
Okay, well what if some packs were to drop out?
I have DC breakers between each pack and my main copper bus bars on the ESS, so I shut one pack down. The others picked up the additional current.
Okay how about 'trip' a few more,
Current increased on the remaining packs.
When I had only two packs online, and all the others off, the current was nearly 85 Amps on each of those two remaining 16s packs. Everything was fine, I had the laser temperature meter - terminals warm but not hot. okay let's see what happens with just ONE pack.
I flipped the breaker on the second-last pack, and the only remaining pack on-line now was going to see 168A ...
"Click" - the BMS shut down charging on overcurrent (my BMS's are all 100A). Interestingly, I have 125A DC breaker between the ESS bus POS and the pack - it didn't trip.
Each pack also has it's own 2P 125 DC breakers, and that didn't trip either. I think the BMS is faster-acting in this situation, since the breaker would take time to heat up under the excessive current, but the BMS is nearly instant.
Anyway the JK did it's job, and shut off on over-current.
So with the final pack shut-down by the BMS, this cut the battery power to my inverters, they need battery 'available' so they shut off on a 'low battery' fault. Leaving me standing in the dark - except for the light from a nearby window LOL.
Restarted everything, all was fine, running normally as usual.
Excess current doesn't cause any harm, if the BMS does it's job. If not, the breaker should trip and cut off the current, but only if the breaker is sized correctly. Looking at a trip curve, it could take considerable time for my 125A breakers to trip with 168A current.
I wonder what the OP's breakers were rated for, and if this perhaps lead to the dominos falling - overheated cables short to the edge of the shelf-angle leading to heating up and fire, venting the cells that then also catch fire, collapse the shelf leading to the broken shunt and other damage we see.
It was a good day for this, solar was excellent and the PV was over 9kW for several hours.
I figured, well lets try a few things and 'see what happens'
First up, I checked how the incoming PV power was being shared between all the packs - checked out nearly equal, 168A incoming, approx 27A on each of 7 packs.
Okay, well what if some packs were to drop out?
I have DC breakers between each pack and my main copper bus bars on the ESS, so I shut one pack down. The others picked up the additional current.
Okay how about 'trip' a few more,
Current increased on the remaining packs.
When I had only two packs online, and all the others off, the current was nearly 85 Amps on each of those two remaining 16s packs. Everything was fine, I had the laser temperature meter - terminals warm but not hot. okay let's see what happens with just ONE pack.
I flipped the breaker on the second-last pack, and the only remaining pack on-line now was going to see 168A ...
"Click" - the BMS shut down charging on overcurrent (my BMS's are all 100A). Interestingly, I have 125A DC breaker between the ESS bus POS and the pack - it didn't trip.
Each pack also has it's own 2P 125 DC breakers, and that didn't trip either. I think the BMS is faster-acting in this situation, since the breaker would take time to heat up under the excessive current, but the BMS is nearly instant.
Anyway the JK did it's job, and shut off on over-current.
So with the final pack shut-down by the BMS, this cut the battery power to my inverters, they need battery 'available' so they shut off on a 'low battery' fault. Leaving me standing in the dark - except for the light from a nearby window LOL.
Restarted everything, all was fine, running normally as usual.
Excess current doesn't cause any harm, if the BMS does it's job. If not, the breaker should trip and cut off the current, but only if the breaker is sized correctly. Looking at a trip curve, it could take considerable time for my 125A breakers to trip with 168A current.
I wonder what the OP's breakers were rated for, and if this perhaps lead to the dominos falling - overheated cables short to the edge of the shelf-angle leading to heating up and fire, venting the cells that then also catch fire, collapse the shelf leading to the broken shunt and other damage we see.
PotusGobbleBottom
Corn Pop was a bad dude.
Thanks for testing this.
robbob2112
Doing more research, mosty harmless
So, looking at pictures it looks like they are these breakers, you can read just enough off the cleaner one to see the make and start of a model but not the series or amps. Looking at the catalog I can't tell if they are rated for DC or not.
www.geya.net
GYCM3-160S Molded Case Circuit Breaker (MCCB) - Geya
GYCM8RT Series Thermomagnetic Dualadjustable Plastic Case Circuit Breaker - Welcome to the future of energy renewable, Geya Electrical’s foray into providing Solar...
www.geya.net
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robbob2112
Doing more research, mosty harmless
I think you are on to the real cause here. It makes the most sense especially when considering someone mentioned he had nuisance trips before
These are the breakers on the Battery/Busbar/InvertersSo, looking at pictures it looks like they are these breakers, you can read just enough off the cleaner one to see the make and start of a model but not the series or amps. Looking at the catalog I can't tell if they are rated for DC or not.
GYCM3-160S Molded Case Circuit Breaker (MCCB) - Geya
GYCM8RT Series Thermomagnetic Dualadjustable Plastic Case Circuit Breaker - Welcome to the future of energy renewable, Geya Electrical’s foray into providing Solar...
GYCM3 DC Molded Case - Best Circuit Breaker Manufacturer
GYCM3 DC Molded Case Circuit Breaker - the future of energy renewable and sustainable, GEYA
www.geya.net
3P 250A, Negative and Positve they were between the bus bar and the battery pack.
None of the breakers actually tripped, they were turned off after the everything was under control, aside from the last 3 which had suffered signifact thermal damage they may have internally tripped but the switch was fused, let me go ding it out with voltmeter.
Okay so Pack 10 The last one that had collapsed onto Pack 6 I couldn't get a ping even though the switch looks to be "On" and Also the BMS was completely melted down and scrapped. So the BMS may have tripped or may not have even had the chance as a the Cell or Cells overloaded.
Pack 6 I got a ding on the breaker that was attached so appears it never closed how ever that attached BMS must have shut down the pack and it doesn't appear all that damaged.
Interestingly Pack9 right next to 10 has a melted switch and is stuck but it appears to internally have opened because I tried getting a ding across it but couldn't get a sound.
From the data in home assistant and what little I can peice together It looks like this was all over in 15 minutes or so, from smoke to Fire department was under 10 minutes.
I've never had any nuisance trips on the DC side of the system.
My grid breaker to my Inverters would sometimes trip from overload due to being set to charge batteries but as they are also supplying load but lack any intelligence to scale back charge current sometimes there was too much draw and breakers do what they are supposed to do.
I never actually saw these breakers trip under overload, so perhaps they don't work but it does appear that 2 of them did trip during the event in particular the main damaged pack where insulation had melted off all the wires it tripped either from overcurrent or heat from the cells burning out.
I explained just above but the breakers were actually turned off after everything happend, how ever I believe all the BMS had cut off anyway, possibly damaged by the fire fighters, over current spike, heat.
All the stats I can see in home assistant show nominal Cell voltages in charge state 3.3V~ 40-70A incoming current to each pack, BMS were 250/125Charge Daly, Shunt 300A rating.
Then what ever happend showed a spike in heat as I'm geussing a cell popped and everything went dead pretty much same time.
2P DC breakers were upto 200A, for 250A you had to size up to 3P.
Packs maybe saw 70~80A briefly if the sun was really good, but most times they would run around 20-50A as the normal.
Cables were 95mm so felt no heat at that load.
I think the fusing of the cable happend during the event and it was only the positive lead that fused on it.
Even if they fused together the BMS was directly after the battery and before those cable so it would have cut out in the event.
I've begun pulling it all apart thoughm probably going to rescue what I can, put them all in some of those rack mount boxes you can buy these days, move them to Air Conditioned shed away from the house.
I will note, Pack 6 the bottom one had a completly destroyed BMS, I haven't got a really close look at it appears the front 2 cells Vented/Burned.
Pack 10 Above it, the BMS is still atached and outwardly doesn't look damaged how ever that pack looks to have lost the front 4 Cells at least.
Pack 6 last communicated with home assistant at 12:17:54 - Charging current reading
Pack 10 last communicated with home assistant at 12:12:21 - Charging current reading
Pack 10 didn't have any temperature updates recorded by home assistant for hours and nothing as the event happend.
Pack 6 spiked from 30C - 46C recorded at 12:17:22.
So I guess the event happend right around that time.
I went to work and took my bike out of the garage at around 6:30AM that day and everything was fine.
Pack 10 Above it, the BMS is still atached and outwardly doesn't look damaged how ever that pack looks to have lost the front 4 Cells at least.
Pack 6 last communicated with home assistant at 12:17:54 - Charging current reading
Pack 10 last communicated with home assistant at 12:12:21 - Charging current reading
Pack 10 didn't have any temperature updates recorded by home assistant for hours and nothing as the event happend.
Pack 6 spiked from 30C - 46C recorded at 12:17:22.
So I guess the event happend right around that time.
I went to work and took my bike out of the garage at around 6:30AM that day and everything was fine.
Those cables leading to the pack never went under that shelf bracket and they had enough slack on them that if the shelf/bracket broke and it dropped they still would not have been out of length and pulling on the breaker.
The breakers were for Positive and Negative.
If the weight of the pack were too break the shelf it would have been the other end where the battery weight is all going from middle to back of the shelf, the front end was barely holding anything.
It's really hard to tell what damage was done during the event and what was done from the chemical extinguishers, but if the panels were really struggling with the weight then being soaked and sprayed I would have expected all or at least some of them to have given in and collapsed.
I'm not sure what happend in the end, and I'll have to spend a lot of time cleaning it all up.
Daddy Tanuki
Solar Wizard
glad you did not run from some of the comments. this if investigated properly can be a real eye opener for some of the folks on the forum.
SilverbackMP
Solar Addict
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Same. Triple redundancy. My BMS (REC) uses contractors that I installed close as possible to the terminals, then a couple of inches past that I have 300A Blue Sea Class T fuses, then 250A MidNite/Carling breakers installed in the (MidNite) battery combiner box/bus bar.
I do have a “thing” that puts a tiny worry at the back of my head. I installed each of the shunts (except one) with good quality wood screws. I should have used through bolts. The pressure of that 4/0 wire on those shunts, contractors, and fuse holders screwed into today’s shitty plywood worries me a bit (used the best I could reasonably get (US birch), but Baltic is unattainium).
I did do this with one, but had to drill out the mounting holes a bit to fit bolts.
Always in the back of my mind that one could break free and land across cell terminals. Likely? No. But possible.
My boxes are an incredible pain the ass to access, but this post is a reminder that I should probably fix this at some point.
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