Last fire.. :-(

[Bob B]

Yes, I saw that picture of the melted post, and yes it obviously got hot and was "possibly/probably" ground zero of the fault. But, why/how could the rest of the cells burn up so uniformly from this "hot spot"?

I thought I saw a picture of that cell with the bus bar still attached .... but can't find it now. Which picture are you talking about that indicates a uniform fire?

 

[Posplayr]

So the second picture shows two different cell types which I assume were in two different banks. These terminals a hideous but I assume that is the result of the damage incurred. Whatever happened seems to have occurred with both sets with the exception on the lower-left cell that actually burned the post.

The other interesting thing I just noticed is, that if those cells are in order of the installation, the cell just above the burned post did not even get hot enough to melt the plastic tape. Now I'm wondering how those terminals all got so bad if they are not hot enough to burn the tape?

 

[mrzed001]

Up in smoke.......

I raise yours to:

scientific:
Up in smoke ... what did I wrong ?

or scholar:
Up in smoke ... learn from my mistake !

or my favorite:
Up in smoke ... I ducked up !

or cooler
Up in smoke ... WTF dude !

 

[curiouscarbon]

“I ducked up!” subforum ?

 

[Will Prowse]

Up in smoke... learn from my mistake!

Did your experimental battery or home built inverter experience a rapid, unplanned disassembly? Reverse polarity a $3K inverter, and see it go up in smoke? Share it here!

diysolarforum.com

Let me know what you think

This site is getting 9 million plus views a month, so this suggestion seemed most professional, and fun haha. Thanks Mrzed001

 

[mrzed001]

Up in smoke... learn from my mistake!

Did your experimental battery or home built inverter experience a rapid, unplanned disassembly? Reverse polarity a $3K inverter, and see it go up in smoke? Share it here!

diysolarforum.com

Let me know what you think

This site is getting 9 million plus views a month, so this suggestion seemed most professional, and fun haha. Thanks Mrzed001

It was @grizzzman 's line ... I only give it a little extra

May I suggest to move the current 4 battery fire case and 1 BMS burn case to this area ? (with the permission of the OP)
One of them is this thread.

upd: and the new Bluetti AC100 fire.

Maybe there are older ones worth saving and highlighting there ?

 

[Will Prowse]

Tag me in a thread that you want moved to the new section and I will do it

 

[Gazoo]

Now I'm wondering how those terminals all got so bad if they are not hot enough to burn the tape?

Maybe he dumped sand on them.

 

[Bob B]

Posplayr said:
Now I'm wondering how those terminals all got so bad if they are not hot enough to burn the ta

Maybe he dumped sand on them.

Yeah ..... I think that was probably a result of putting out the fire .... and maybe the smoke from the fire is corrosive as he showed in the pictures of his inverter that failed.

 

[Posplayr]

Maybe he dumped sand on them.

Yea maybe, but how did the sand get under the bus bars?

 

[Gazoo]

Yea maybe, but how did the sand get under the bus bars?

Good point. Why don't we ask?

@fhorst What happened to the terminals of your cells? Maybe you posted it and I missed it. Why do all the cells terminals in the photos above look so nasty Thanks.

 

[Posplayr]

Posplayr said:
Now I'm wondering how those terminals all got so bad if they are not hot enough to burn the ta


Yeah ..... I think that was probably a result of putting out the fire .... and maybe the smoke from the fire is corrosive as he showed in the pictures of his inverter that failed.

So in the first post, it looks like OP just dumped a bunch of sand on the lower level. At this point, I don't know if he was mixing cell capacities in that level or what configuration it might have even been in. We don't even know if the pictures of the disassembled cells are even in the order that they were installed, but perhaps they are and to the extent that they all look all very similar maybe it doesn't even matter.

If the cells were brushed off (with say a brush or broom), then we would have a better idea as to whether that crude on all the cells is bonded silica (ie. sand) or burned grease from the anti-corrosion treatment? It looks like it has bonded to the cells which are probably related to elevated heat, which would be indicative of high but balanced currents which is also an indication that all the cells were involved in a similar current loop (i.e. one bank discharging into the other). If this is the case, then a BMS with cutoff would have stopped the big current loop but would have done little for an internal short with the single cell.

Without any further clarification, I can summarize what it looks like:

1.) One post on one cell was basically destroyed indicating an imbalance in the cell current flow and a likely short in and around that post. Any current flow to that damaged post would have to be balanced by the current leaving the opposite post. Since the opposite post is not damaged there was obviously a much higher generation of heat developed at that point.

Now one could claim that it is a dirty post that caused elevated heat, but that does not explain why all the other cells seem to have dumped their energy into this cell. Nor does it even explain why there would have been elevated currents which are clearly indicated by the state of all of the posts. The sand appears to be bonded/heat oxidized to all the posts and not simply sitting on top.

This is not from a normal load charge/discharge cycle. It is indicative of high elevated currents through all cells. However, the heat of this fire which may have in the OP's own words "been hotter than a bakery oven", since it did not even melt the aluminum cases, it was not much above 1100 deg F melting point of AL except in the direct proximity of the burned post. The evidence points to a long sustained drain of energy from many if not all the cells into the short at the single post.

2.) Had there been separate BMS's with disconnects on the parallel strings, the big energy dump would NOT have occurred. The single cell that shorted would have expended itself, and that string would have been disconnected by the BMS. The fire might have lasted for 1 hour instead of 24 hours, involved only that single cell, and left the remaining cells largely intact if not totally unaffected.

We can conclude this because, with all the energy that was expended, even the damaged cell still only melted a small portion of its thin aluminum case! The crude on all the other cells strongly suggests that they all were under high load and dumped their energies into this single post, and as such this single cell was subjected to a much higher thermal stress than any other post but that sustained current dump still did relatively minor damage to the cell. Essentially if the cell was so damaged that it could not support a current then the source of energy release would have been removed.

Finally, I feel compelled to make the following statements not to disparage the OP, but more to provide some explanations for any other DIY'er that may look at the thread in horror and be dissuaded from building their own DIY battery bank.

Caution of LiFePO4 is warranted but also understanding that the OP violated some fundamental best practices (i.e. no BMS with an automatic current disconnect) also needs to be understood. The violation of this best practice seems to be the primary contributor to the cascading meltdown of something that would have otherwise been easily confined to a single cell. While the OP seems to be very diligent in his efforts to construct this battery system, those efforts are based on what amounts to a trial and error process where error means "smoke release" from the electronics.

There are other best practices being violated (i.e. spaghetti wiring) which in my estimation did not contribute to this melt down, but that doesn't mean that it might not create some other problem further down the road. One of the biggest problems with trial and error development (one not involving understanding the engineering and designing to mitigate risks) is that there is a presumption that something is safe because it has not failed yet when in fact it may be that it just has not bitten you yet. I think this episode is an example of that where the potential danger of running without a BMS was not fully appreciated.

In the engineering domain, something called Failure Mode and Effect Analysis (FMEA) is part of a set of standard practices for analysis of what can go wrong/fail and in the event of those failures what the effects of those faults are predicted to be. A cursory FMEA of parallel strings of cells will quickly lead to the realization of the potential for unprotected (e.g. no BMS) parallel strings to dump all energy into a single shorted cell.

What is FMEA? Failure Mode & Effects Analysis | ASQ

Learn when to use the failure modes and effects analysis (FMEA) and the general procedure an organization should follow through an FMEA example at ASQ.org.

asq.org

Hopefully, this provides some potential explanations for the incident and I think is far more productive than coming up with funny names for this thread. We have to appreciate the OP's willingness to share this disaster in the hopes of avoiding similar things for himself but also for others in the future. Any form of jokes/comedy is in my opinion misplaced, inappropriate, and immature which ultimately counter to the stated goals of this forum for sharing information and will lead to dissuading any future OP's from sharing their failures.

 

[curiouscarbon]

The names, I think, are meant more to cheer people up after feeling bad from the error/fail, than to ridicule but they are non-technical in nature
Speaking for myself, I have invested a decent amount of hope into these systems I'm building. When they fail, emotionally, that'll probably be not as fun as the successful commissioning part. That's why it's important to be kind. But if I did something that caused it to go up in flames, then at some point I might need to hear something that makes me feel uncomfortable. Hopefully I'll be ready with thick skin and they'll be respectful ?

FET disconnect and Solenoid Contactor are two components I am forcing myself to include in all my builds going forward, to protect against fire.

Earlier in the thread, @fhorst made it clear that this was a disaster, mitigated by support from family helping to replace the hardware.

The fact that nobody was hurt (that I read, sorry if i missed a detail) and that the system will be rebuilt are what make me feel safe enough to be a little lighthearted in this specific context...

I am so glad only hardware was lost. These cells can be manufactured again, but loved ones cannot.

Extremely grateful for everyone trying to analyze what happened so that everyone can be a bit safer going forward!

 

[Gazoo]

Hopefully, this provides some potential explanations for the incident

Thanks for the novel but I would prefer an explanation from the OP regarding the terminals.

 

[Posplayr]

Thanks for the novel but I would prefer an explanation from the OP regarding the terminals

You are welcome to disregard my postings, although you seem to have difficulty with that.

 

[Posplayr]

The names, I think, are meant more to cheer people up after feeling bad from the error/fail, than to ridicule but they are non-technical in nature
Speaking for myself, I have invested a decent amount of hope into these systems I'm building. When they fail, emotionally, that'll probably be not as fun as the successful commissioning part. That's why it's important to be kind. But if I did something that caused it to go up in flames, then at some point I might need to hear something that makes me feel uncomfortable. Hopefully I'll be ready with thick skin and they'll be respectful ?

FET disconnect and Solenoid Contactor are two components I am forcing myself to include in all my builds going forward, to protect against fire.

Earlier in the thread, @fhorst made it clear that this was a disaster, mitigated by support from family helping to replace the hardware.

The fact that nobody was hurt (that I read, sorry if i missed a detail) and that the system will be rebuilt are what make me feel safe enough to be a little lighthearted in this specific context...

I am so glad only hardware was lost. These cells can be manufactured again, but loved ones cannot.

Extremely grateful for everyone trying to analyze what happened so that everyone can be a bit safer going forward!

Intent and perception are two different things. I have certainly seen several posters in this thread refrain from making the situation any more difficult for OP. I'm certainly sensitive to that as well, but recognize that understanding the root cause is in everybody's best interest whereas "cheering people up" at OP's expense is not.

 

[Gazoo]

You are welcome to disregard my postings, although you seem to have difficulty with that.

I don't know where you are coming from with the "you" thing? As far as I know this is the second time I have replied to you. Maybe I forgot another time? I enjoy reading your posts but I want to hear from the OP and would like for him to have a chance to respond.

 

[Posplayr]

I don't know where you are coming from with the "you" thing? As far as I know this is the second time I have replied to you. Maybe I forgot another time? I enjoy reading your posts but I want to hear from the OP and would like for him to have a chance to respond.

That is all well and good but you seem to be under the impression that I am getting into the way of that. This is the second time you have mentioned that. Maybe you should tell the OP rather than me.

 

[mrzed001]

Guys, play nice

 

[Mcgivor]

So in the first post, it looks like OP just dumped a bunch of sand on the lower level. At this point, I don't know if he was mixing cell capacities in that level or what configuration it might have even been in. We don't even know if the pictures of the disassembled cells are even in the order that they were installed, but perhaps they are and to the extent that they all look all very similar maybe it doesn't even matter.

If the cells were brushed off (with say a brush or broom), then we would have a better idea as to whether that crude on all the cells is bonded silica (ie. sand) or burned grease from the anti-corrosion treatment? It looks like it has bonded to the cells which are probably related to elevated heat, which would be indicative of high but balanced currents which is also an indication that all the cells were involved in a similar current loop (i.e. one bank discharging into the other). If this is the case, then a BMS with cutoff would have stopped the big current loop but would have done little for an internal short with the single cell.

Without any further clarification, I can summarize what it looks like:

1.) One post on one cell was basically destroyed indicating an imbalance in the cell current flow and a likely short in and around that post. Any current flow to that damaged post would have to be balanced by the current leaving the opposite post. Since the opposite post is not damaged there was obviously a much higher generation of heat developed at that point.

Now one could claim that it is a dirty post that caused elevated heat, but that does not explain why all the other cells seem to have dumped their energy into this cell. Nor does it even explain why there would have been elevated currents which are clearly indicated by the state of all of the posts. The sand appears to be bonded/heat oxidized to all the posts and not simply sitting on top.

This is not from a normal load charge/discharge cycle. It is indicative of high elevated currents through all cells. However, the heat of this fire which may have in the OP's own words "been hotter than a bakery oven", since it did not even melt the aluminum cases, it was not much above 1100 deg F melting point of AL except in the direct proximity of the burned post. The evidence points to a long sustained drain of energy from many if not all the cells into the short at the single post.

2.) Had there been separate BMS's with disconnects on the parallel strings, the big energy dump would NOT have occurred. The single cell that shorted would have expended itself, and that string would have been disconnected by the BMS. The fire might have lasted for 1 hour instead of 24 hours, involved only that single cell, and left the remaining cells largely intact if not totally unaffected.

We can conclude this because, with all the energy that was expended, even the damaged cell still only melted a small portion of its thin aluminum case! The crude on all the other cells strongly suggests that they all were under high load and dumped their energies into this single post, and as such this single cell was subjected to a much higher thermal stress than any other post but that sustained current dump still did relatively minor damage to the cell. Essentially if the cell was so damaged that it could not support a current then the source of energy release would have been removed.

Finally, I feel compelled to make the following statements not to disparage the OP, but more to provide some explanations for any other DIY'er that may look at the thread in horror and be dissuaded from building their own DIY battery bank.

Caution of LiFePO4 is warranted but also understanding that the OP violated some fundamental best practices (i.e. no BMS with an automatic current disconnect) also needs to be understood. The violation of this best practice seems to be the primary contributor to the cascading meltdown of something that would have otherwise been easily confined to a single cell. While the OP seems to be very diligent in his efforts to construct this battery system, those efforts are based on what amounts to a trial and error process where error means "smoke release" from the electronics.

There are other best practices being violated (i.e. spaghetti wiring) which in my estimation did not contribute to this melt down, but that doesn't mean that it might not create some other problem further down the road. One of the biggest problems with trial and error development (one not involving understanding the engineering and designing to mitigate risks) is that there is a presumption that something is safe because it has not failed yet when in fact it may be that it just has not bitten you yet. I think this episode is an example of that where the potential danger of running without a BMS was not fully appreciated.

In the engineering domain, something called Failure Mode and Effect Analysis (FMEA) is part of a set of standard practices for analysis of what can go wrong/fail and in the event of those failures what the effects of those faults are predicted to be. A cursory FMEA of parallel strings of cells will quickly lead to the realization of the potential for unprotected (e.g. no BMS) parallel strings to dump all energy into a single shorted cell.

What is FMEA? Failure Mode & Effects Analysis | ASQ

Learn when to use the failure modes and effects analysis (FMEA) and the general procedure an organization should follow through an FMEA example at ASQ.org.

asq.org

Hopefully, this provides some potential explanations for the incident and I think is far more productive than coming up with funny names for this thread. We have to appreciate the OP's willingness to share this disaster in the hopes of avoiding similar things for himself but also for others in the future. Any form of jokes/comedy is in my opinion misplaced, inappropriate, and immature which ultimately counter to the stated goals of this forum for sharing information and will lead to dissuading any future OP's from sharing their failures.

There are a few other factors which may need to be considered, first is the time line of events, power goes off early in the morning before sunrise, then restores later after sunrise, hense charging has begun, then the fire occurs.

Secondly the possibility of rodent damage to insulation is extremely high in Thailand especially in closed spaces like between the stacked battery arrangement, this can go unnoticed resulting in faults or failure. One of the many sense wires, which may have been missing insulation, could have contacted a busbar at excessive voltage for a single cell, this could overwhelm the cell to the point of failure.

Protection against rodents, especially in the tropics, is something to taken seriously, on my pickup alone they disabled the wipers, indicators, a fuel injector, fuel door release, eaten the cabin air filter and the engine air filter, all in three years since new. My main battery cables of a solar system, which were in an unsealed PVC duct, were stripped if insulation until they shorted, thankfully the overcurrent protection did it's job, they have also disabled a system by chewing through a BMS sense wire.