House burned down

[B-ManFX4]

I have read every post in this thread. My sincere best wishes to the OP and his family. That is a horrible experience. If there is a donation web site someone please post a link - I will gladly contribute. I can't imagine the depth of the loss they are now going through. Amazing courage to post the information he has - you certainly open yourself up to question / ridicule / speculation / etc. Thanks for sharing - I am going to make a few additions to my power room based on your experience.

I myself have two 16s 304AH banks in two separate Apexium boxes. I am trying to visualize how the fuse that the fire inspector says was the root cause could have started a fire intense enough to ignite a chain reaction. In my system, the fuse is literally the last thing between the BMS and the positive battery post connection. For the fuse to blow there would have to be massive current flowing either into or out of the battery.

That leaves me with a few possibilities:

1. My inverter / chargers suffer some catastrophic failure and start dumping mega amps into the battery AND the inverter / charger AC input breakers failed to trip.

2. Something in my inverter chargers failed and the battery started dumping mega amps into them AND both battery BMS's did not disconnect AND the battery output fuses didn't blow.

3. If a single cell in the 16s string internally shorted there could be massive current flow within the battery itself - but how would the fuse at the end of the string blow? The current within the cell to cell short would be "behind" the fuse - the current would not be flowing out to the load.

In the OPs case I don't believe the fuse caused anything to happen. I believe the bank had an internal cell failure, a fire ensued, something on the load side is damaged by the fire and then started conducting hard enough to overload the fuse. Had the fuse popped or not, it would not have mattered - the excessive current draw was behind the fuse and the fire was already initiated.

On an RV forum I frequent, a member posted pictures of a LiFePO4 cell that he and his wife both saw flames shooting out of a bottom corner of the cell. The system was not in use at the time. The corner looked like a blow torch had been used from the inside out. Several others commented that "LiFePO4 can't burn like that" and his response was "My wife and I both saw the flames and I threw the entire battery outside of the RV." In the pics he posted it appeared the cell ruptured the bottom corner facing outward so the flame was not directed at the neighboring cells. I have been searching for that thread but have not had any luck finding it yet.

Based on what I have read in this thread, I am going to make a few changes and additions to my power room. These will include new ionization smoke detectors that also have a relay in the base. That relay will be wired to a Tyco 500 amp contactor placed immediately after the fuse inside each Apexium box. If either smoke detector is activated the relays will de-energize the battery circuit to the inverter / chargers. I am also going to install a ducted fan that will vent to the outside world in the hopes that a cell off-gassing event will be mitigated enough to prevent ignition or explosion.

Finally - my power room is concrete slab with 3 wood framed stud walls. I am going to sandwich 5/8" Firecode X Drywall - 1/2" cement board - 5/8" Firecode X Drywall for the three exposed wood stud walls and the ceiling. The 4th wall is cinder block so no burn potential there.

 

[kolek]

I am saying that a bad cell from the same batch would have shown its colors earlier than now.

@robbob2112 Correct me if I'm wrong, but I think you're making 2 assumptions:

First, regarding the cell venting a couple years before the fire, you're maybe assuming that the probability of getting a faulty grade A battery from Luyuan is higher than the probability that the OP made a mistake somewhere in his build or in his treatment of his cells. To me, this is improbable. Maybe we agree on this point.

Second, you are assuming I said bad cells maybe caused the fire, and actually what I'm saying is whatever caused the cell to vent originally may have also caused the fire, but we'll never know, because the OP said he didn't investigate the original venting incident, and just chalked it up to a faulty battery.

Anyway, I have nothing more to add, at this point I just hope the OP recovers soon from this terrible incident. Good luck OP and thanks again for helping us learn.

 

[RV8R]

So, after 4 to 5 years of working flawless, the 100 kwh lifepo4 battery caught fire at night and burned our house down. Luckily our family just made in out on time.
Inspection of the fire expert revealed that a melt fuse melted, and created an arc between the 2 points wich ultimatly started the fire.
So i learned to not use melt fuse anymore, plus once the house is rebuild, i will put the new system in a seperate shed outdoor.

@Jejochen

I am very sorry that happened to You & Your Family, & I am glad all of you made it out alive & seemingly not physically injured.

I wanted to post here & state how grateful I am for your bravery & reporting of your personal disaster. Your selfless act of bringing this to the attention of other Forum Members, I Believe has caused pause & review of our DIY systems with safety at the forefront;



Post in thread 'Spinoff from house burning LFP vs AGM vs Lead Acid - Why not just run the older tried and true stuff?'
https://diysolarforum.com/threads/s...older-tried-and-true-stuff.83282/post-1081401

 

[kolek]

I probably meet 3, if not all 4, of those criteria

I can hear someone in the background complaining "I swear, she loves those batteries more than me!!" lol

 

[Shimmy]

If you add a Class T fuse for each 16S string, there won't be a problem. No contactor needed.

Insufficient information to make that determination. The Mega Fuse was the second failure we can see based on the shunt data.

It is likely that the fuse would have provided string isolation, but relying on the fuse for that is a misapplication. Your primary protection for string isolation should be a string level contractor or shunt trip. The fuse is there to protect the contactor and the wiring.

 

[Jejochen]

Hi all,
I'm really not asking for anything, but someone asked, so here is a link of an action my friends set up:

Steun veerle jochen en hun kids na brand | Steunactie.be

Veerle jochen en hun kids , verloren alles door een woning brand. Help mee zodat ze terug hun leven kunnen opbouwen

steunactie.be

I wanted to "report" this fire to you all as in my opinion it is the right thing to do as it maybe can help others prevent it, and i wont say its easy.
Im typing this literally from a hospital bed. Adrenalin makes you go trough the first days, but now i know theres a rebound.

I have not read it all, but i can certaincly say when a new system is installed, it will be with the "t" fuses. Wishes i knew about them years ago.

Be safe guys.

 

[Zwy]

if I'm interpreting this picture correctly, the 16s strings didn't have separate fuses, as the fuse is after the common bus bar ?
View attachment 212805

Far right are the fuses, holders have a black cover.

 

[robbob2112]

@robbob2112 Correct me if I'm wrong, but I think you're making 2 assumptions:

First, regarding the cell venting a couple years before the fire, you're maybe assuming that the probability of getting a faulty grade A battery from Luyuan is higher than the probability that the OP made a mistake somewhere in his build or in his treatment of his cells. To me, this is improbable. Maybe we agree on this point.

Second, you are assuming I said bad cells maybe caused the fire, and actually what I'm saying is whatever caused the cell to vent originally may have also caused the fire, but we'll never know, because the OP said he didn't investigate the original venting incident, and just chalked it up to a faulty battery.

Anyway, I have nothing more to add, at this point I just hope the OP recovers soon from this terrible incident. Good luck OP and thanks again for helping us learn.

#1 - I assume that something caused a cell to short... a case to case short would do that by shorting out 1 cell.... an internal short of 1 cell would do that as well.... the whole battery bank charging to a lesser voltage than its companions would potentially do that, uneven cable length could cause this but would probably have been an issue before now....

User's regular schedule with a thermal camera only proves nothing was wrong that was physically/visibly detectable.
The earlier math shows what happens in the event of a short or bank imbalance.
And whatever it was we will never know.

#2 - You are correct, I was assuming that.

 

[Zwy]

Insufficient information to make that determination. The Mega Fuse was the second failure we can see based on the shunt data.

It is likely that the fuse would have provided string isolation, but relying on the fuse for that is a misapplication. Your primary protection for string isolation should be a string level contractor or shunt trip. The fuse is there to protect the contactor and the wiring.

I strongly disagree, Class T on each 16S string to ensure no current will flow.

I'm building another bank and I will not be relying on the JK BMS's to cut current in a catastrophic failure but will rely on the Class T fuses. I want nothing with a mechanical operation.

 

[Zwy]

3 phase system
The data you see starts at midnight and ends 4 hrs later

Can you zoom in the last hour or less?

 

[k490]

This is why my batteries will be enclosed in steel with 1/4" plate steel on top. Haven't had time to weld it together yet been busy with other projects soon it will be built. The box will weigh 250lbs itself I have casters already roll it around my garage. The only thing that keep this from burning down your home is incase it in steel. After reading this thread I might even add more steel to it I have some 1/2" steel plates was going to use for target shooting, but might weld this on the box also.

How many of you have reviewed your insurance policy carefully? I went thought mine it's 78 pages there was 10 pages of exclusions nothing directly related to lithium batteries, solar, or unpermitted electrical work. 50% of the homes probalby have un-permitted work done unless they are brand new.

This is all I could find maybe they could try and throw at you.

 

[Supervstech]

I would like to understand how OP had 7 strings tied to a single set of watchmons...

It looks like each bank was a full set.
Parallel should be done all together, so all cells are tied to a single bussbar, then put those in series.

Pics of the build in depth would be great.

 

[Hedges]

Class T or any other fuse only stops current flow after some time/current curve is exceeded.
A bad cell and reverse current could continue for an extended time, certainly enough to totally cook, outgas, rupture a cell, unless the configuration of paralleled strings drove enough current to eventually blow the fuse.

A BMS and contactor should isolate the string if cell voltage gets out of whack. But does it open contactor and stop charging current when string voltage or cell voltage is too low? In OP's system, overall pack was discharging, one string may have been charging, something BMS probably doesn't measure (no shunt per string). What does it do if a single cell is far out of balance and low? Does it try to allow charging, or shut everything down? FMEA has to be performed to design failure handling.

Fuse may have been source of ignition, maybe even of combustible objects rather than gas. But something else was the failure, causing over-current. Unless electronics failed and drew excess, it seems battery string/cell failed and started over-charging cells and outgassing them. Bad cell may have become short/low impedance drawing enough current to blow the fuse. I figure fuse may have been the match which started the conflagration.

Even if a better fuse that didn't blow with blast of plasma, a room full of flammable gas is a bad thing. Light switch could set it off when someone walked in.

Fuses needs to be one rated AIC for max fault current available. Should be safe for explosive atmosphere if that is a possibility (in a boat or a battery room.) Should be enclosed to protect people if it blows up. There are videos of how different sorts of fuses blow (with a test dummy), and enclosures for fuses & breakers to protect people.

Even if the initiation of fire was at the fuse, unless there was something combustible like paper or wood that it ignited, I'm disinclined to blame the fuse. More likely vented flammable gas.

But maybe the inspector is doing OP a favor by pointing at a commercial (UL listed?) part as the cause. He can say that with a straight face, regardless of the environment provided.

OP had said the battery systems he was installing were approved, for insurance purposes. Were they similar to this one? Need to revisit them and modify?

 

[Jejochen]

I would like to understand how OP had 7 strings tied to a single set of watchmons...

It looks like each bank was a full set.
Parallel should be done all together, so all cells are tied to a single bussbar, then put those in series.

Pics of the build in depth would be great.

Watchmon 4 was build for this. Just daisychain all the cells like you would normally do, but dont stop at 16, stop at cell 112. In the software specify 16s, 7 banks. Done.

 

[summit]

Far right are the fuses, holders have a black cover.

yes exactly, thus these fuses are after the common B+ bar. But that picture was with the initial 3x16s strings configuration, not the later with 7-string. It's unclear if it was a single fuse zapped from the fire investigation report, as the fuses were co-located.

 

[Jejochen]

yes exactly, thus these fuses are after the common B+ bar. But that picture was with the initial 3x16s strings configuration, not the later with 7-string. It's unclear if it was a single fuse zapped from the fire investigation report, as the fuses were co-located.

Indeed. Fuse was 1 of the 7 fuses between banks and busbar.

 

[Luk88]

If anyone is interested in a really good fire detection method I recently evaluated a surprisingly cheap thermal Cctv Camera. Its model number is Dahua Kamera IP Dahua TPC-DF1241-D3F4 they come with different lenses, but this particular one (D3F4 on the end) is one of the cheapest(I paid $275, but then I returned it). There is a new model on the market called S2 and the old one one has certain software issues, for example too weak cpu for reliable AI person detection so it can be bought cheaply.

I evaluated one for security. The thermal image wasn't as good as I wanted at 100m+ distances, but now that I'm reading this thread I think it wouod make a great fire detector. It has such feature and it has a relay output. So no programming is necessary. If I had a large battery bank at home I'd put such camera facing it. Just an idea.

 

[kolek]

If anyone is interested in a really good fire detection method I recently evaluated a surprisingly cheap thermal Cctv Camera. Its model number is Dahua Kamera IP Dahua TPC-DF1241-D3F4 they come with different lenses, but this particular one (D3F4 on the end) is one of the cheapest(I paid $275, but then I returned it). There is a new model on the market called S2 and the old one one has certain software issues, for example too weak cpu for reliable AI person detection so it can be bought cheaply.

I evaluated one for security. The thermal image wasn't as good as I wanted at 100m+ distances, but now that I'm reading this thread I think it wouod make a great fire detector. It has such feature and it has a relay output. So no programming is necessary. If I had a large battery bank at home I'd put such camera facing it. Just an idea.

@Luk88 I can't seem to find that anywhere for sale for anything close to $275. Do you have a link?

 

[Ampster]

About being the fuse the source as the fire according to the fire inspector: i never said he said the fuse is the reason the system started to fail. Only it is there the fire started, and as he talked me through the entire research process, i strongly tend to agree with him.

Thanks, that is an important clarification. The system failure is the big unknown. Good luck with your recovery. I understand the melted fuse in a different light, or a different heat issue for that matter. Your unfortunate loss has generated a lot of constructive thought around safety.

 

[Supervstech]

Watchmon 4 was build for this. Just daisychain all the cells like you would normally do, but dont stop at 16, stop at cell 112. In the software specify 16s, 7 banks. Done.

Oh, so you should have BMS data for all 112 cells, no?