House burned down

[Brucey]

Batrium bms i thought and still think is a great bms. I have no idea why 1 central bms for 112 cells is "bad". If something is wrong with the system design, thats possible, but thats not the bms to blame, it did always a great job.

If you had a watchmon and a relay/disconnect per string, you have more fine grained control of things and potentially wouldn't have this potential series to series cascade failure.

In the design you had there is no way for the Batrium to clamp down/disconnect a problematic string. All of that energy is free to do what it wants because it is all behind the single watchmon contactor. I would say the warnings that are provided in the Orion BMS documentation about parallel string without ability to disconnect individual sytings would also apply to your Batrium watchmon design but they only have a small section about system qualifications and not using breakers ambetween the multiple banks

 

[Luk88]

So according to the OP, a grade A cell from Luyuan that had been treated exactly according to guidelines, spontaneously expands and vents for no reason.

I'd be very curious to hear expert opinions on this.

I'm not an expert, but I sure do have an opinion

Can this actually happen, and if so, what is the rough probability of it happening? I would have assumed it's practically impossible, or maybe 1 chance in 10,000. I thought these cells are extremely stable, especially the "real" grade A ones from Luyuan, and if they do expand and vent, you must have done something to provoke them.

Not blaming the OP of course, just curious because many of us on the forum have grade A cells from Luyuan and if they are spontaneously failing, that is a major concern.

IMO, this is electrochemistry with huge amounts of energy stored separated by very little material. There is always a possibility of material failure, or process failure at the plant. Separator weak spot, bad mixing of solids that happened in one particular spot etc. No doubt a huge percentage of such issues cause cells to fail QA tests, but things do slip. Although rare, we do have EV car fires now and then and they have always had the best quality cells. Personally I think a chance a cell fails like this based on a manufacturing issue is much lower than 1 in 10000. But probability exists.

And if large number of people use these cells... sadly some houses will burn. There is a reason why there is regulation in my country that there has to be smoke detection in the same room as domestic batteries(also some silly regulation, like if tyhe battery is installed underground it needs to be elevated by 30cm - I never heard flooding is generally limited to 30cm...why not 10cm, or 1m?). Earlier in this thread someone posted a link to show a small CO2 air displacement fire extinguising system. If I had a large lifepo battery in my house I'd definitely install this in a room where it's at. Or consider the battery enclosure a furnace. Make it from heavy gauge steel and vent it outside. Lifepo is probably the safest lithium chemistry there is, but still it contains flammable liquid under pressure (in case of failure and subsequent heat buildup). It just takes a spark to ignite it. A spark, like from a blowing melt fuse.

Personally I don't have more trust in ready made batteries. Some are equipped with fire supression, but what kind? Is it going to displace oxygen in the entire room? If yes, it can be potentially as deadly as a fire itself if the user is unaware, if not, I'm not sure how it can work.

 

[Brucey]

If you had a watchmon and a relay/disconnect per string, you have more fine grained control of things and potentially wouldn't have this potential series to series cascade failure.

In the design you had there is no way for the Batrium to clamp down/disconnect a problematic string. All of that energy is free to do what it wants because it is all behind the single watchmon contactor. I would say the warnings that are provided in the Orion BMS documentation about parallel string without ability to disconnect individual sytings would also apply to your Batrium watchmon design but they only have a small section about system qualifications and not using breakers ambetween the multiple banks

Note the section at the bottom, if there is a breaker (or in your case fuses) between each bank, that's not what Batrium considers multi string and you need a watchmon per string.

 

[Zwy]

What voltage is the system?
Just under 3kW on a single phase.
Is that the last info the bms recorded? Last info of the solar assistant?

Not off Batrium, appears to be Victron, look at the icon on the upper left.

The reason WHY a single bms is bad for several strings of cells is, you have no data for issues causing the bad cell.

Not true.

You have no data for issues discharging each string.

I'll give you this one, but when using a BMS for each 48V battery, can one view all the batteries and cells at the same time on one screen?

Rhetorical.

Same reason why a single fuse is bad for three sets of batteries.

OP had a fuse for each 16S 48V set.

Zero protection for the other strings, if one goes bad...

Batrium has plenty of data, way more than the standard BMS. Also has way more settings and adaptability.

 

[Zwy]

Note the section at the bottom, if there is a breaker (or in your case fuses) between each bank, that's not what Batrium considers multi string and you need a watchmon per string.

View attachment 212777

View attachment 212779

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

As for multi bank, of course you would need another Watchmon CORE. And another shunt trip.

 

[G00SE]

I probably read your post as this cell doing that now in this event, not three years ago.

It is an interesting observation. Might not be relevant to the event we are discussing. But what caused a luyuan grade A cell to vent to begin with

 

[Tulex]

It is an interesting observation. Might not be relevant to the event we are discussing. But what caused a luyuan grade A cell to vent to begin with

My thought is that the reason we don't see this in manufactured batteries is that they don't put the cells we can purchase in them. Chances are that even though the numbers look good on the cells we can buy, something probably shows up in testing that they don't like. These cells are "Grade A" as far as capacity goes, but not necessarily in quality. We are literally buying batteries at the bargain outlet/Mr. Seconds.

 

[robbob2112]

This post is nothing without a suitably explosive video!!! Where are The Mythbusters when you need them?

Enjoy!

Sorry, I do not intend anything so colorful. Instead I intend to use a clamp meter and victron shunt to watch the current and gradually increase it until past the rated amps and time the blow...not as much fun I know, but safer and more meaningful.

 

[SparkyJJO]

Sorry, I do not intend anything so colorful. Instead I intend to use a clamp meter and victron shunt to watch the current and gradually increase it until past the rated amps and time the blow...not as much fun I know, but safer and more meaningful.

I want to see dead short results.

 

[B-ManFX4]

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

To be fair almost all melted / burnt fuse holders are caused from poor connections, not from faulty fuses. There's a huge difference.

 

[kolek]

It is an interesting observation. Might not be relevant to the event we are discussing. But what caused a luyuan grade A cell to vent to begin with

Exactly.

Nothing against how the OP handled the situation, and hindsight is always 20/20, but if one of my grade A cells from Luyuan vented and swelled up suddenly, I would first assume there was something wrong with something in my system. Much more likely that I had made a mistake or there was a problem with my system than the Luyuan factory shipped a bad cell. My last thought would be the possibility that this grade A battery was faulty from the factory.

Of course we're just guessing with these estimates, but @Luk88 also just estimated that the chance of a grade A battery from Luyuan expanding and venting for no reason is maybe less than 1 in 10,000.

But the OP says he assumed the battery itself was the problem and didn't investigate:
"Imo the leaking cell was an exception. Sometimes things just break. Thats why i didnt gave it any futher attention."

Anyway, personally I would not be surprised if the two events, the case of the battery venting and the eventual fire which happened a few years later are related.

 

[robbob2112]

I want to see dead short results.

buy your own... I paid $38 for these, the largest part was for the ceramic holders...... and I don't have the setup to safely do a dead short.

 

[Mattb4]

Thinking about this a bit this morning an idea for a safety alarm besides the smoke detectors struck me. Perhaps a thermal detector for rooms that if the ambient temperature rises beyond a reasonable value (85F) the klaxons get set off and the sirens wail. Maybe some spot temperature sensors near equipment.

 

[robbob2112]

Exactly.

Nothing against how the OP handled the situation, and hindsight is always 20/20, but if one of my grade A cells from Luyuan vented and swelled up suddenly, I would first assume there was something wrong with something in my system. Much more likely that I had made a mistake or there was a problem with my system than the Luyuan factory shipped a bad cell. My last thought would be the possibility that this grade A battery was faulty from the factory.

Of course we're just guessing with these estimates, but @Luk88 also just estimated that the chance of a grade A battery from Luyuan expanding and venting for no reason is maybe less than 1 in 10,000.

On the other hand, what are the odds that the cell was fine from the factory, and the expanding and venting was caused by something external, maybe a problem with the BMS or whatever? The probability of that would seem to be much higher than 1 in 10,000. A battery is a relatively simple single discrete component, whereas in a system, there's lots of potential problems with lots of different components, and there's lots of external factors which could have caused that event.

But the OP says he assumed the battery itself was the problem and didn't investigate:
"Imo the leaking cell was an exception. Sometimes things just break. Thats why i didnt gave it any futher attention."

Anyway, personally I would not be surprised if the two events, the case of the battery venting and the eventual fire which happened a few years later are related.

I think you are beating a dead horse.... 3 years later with weekly routine checks and nothing... is it possible other cells were damaged? sure, but I think they would have shown their issues in the intervening 3 years.

 

[robbob2112]

Thinking about this a bit this morning an idea for a safety alarm besides the smoke detectors struck me. Perhaps a thermal detector for rooms that if the ambient temperature rises beyond a reasonable value (85F) the klaxons get set off and the sirens wail. Maybe some spot temperature sensors near equipment.

A raspberry pi with sensors tucked in around the room and in the gear. You can do the 1-wire sensors on it and tack on as many as you like. Each has its own ID so simple enough to label them all.

I used to use one on a wall behind and a few feet in front of a resistive heater to track ambient temp in a small room. But it also told me when the heater was on and off. I've since repurposed it to have a sensor in the aquarium and a sensor outside to tell when the water temp is low and give an alarm.

These sensors + a resistor tied to the pi in series. (I know out of stock, but many look alikes available)

https://www.amazon.com/gp/product/B00QGN0LKY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The actual sensor

https://www.amazon.com/gp/product/B007STHA22/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[SeaGal]

When you take the safety element and the time investment into account, buying finished batteries is just smarter for most people. Unless you're too cheap or too poor to afford pre-built batteries, or your life is devoid of other more worthwhile pursuits, or you're doing it for the sake of learning, and/or you derive some kind of perverse enjoyment from DIY battery-build projects.

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

 

[kolek]

I think you are beating a dead horse.... 3 years later with weekly routine checks and nothing... is it possible other cells were damaged? sure, but I think they would have shown their issues in the intervening 3 years.

So if it was you, you'd do weekly routine checks when everything appeared to be running fine, but not actively seek out potential causes after a grade A cell suddenly swelled and vented out of the blue?

 

[robbob2112]

So if it was you, you'd do weekly routine checks when everything appeared to be running fine, but not actively seek out potential causes after a grade A cell suddenly swelled and vented out of the blue?

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

 

[summit]

OP had a fuse for each 16S 48V set.

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

 

[robbob2112]

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

Read the whole thread the OP started on a power wall. He started with 3 strings and increased to 7 over time and totally reorganized things.

 

[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.