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diy solar

So this happened today

plaidcabin

New Member
Joined
May 3, 2021
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28
He was so proud of his new 48v parallel series configuration. Charging the cells up...
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How it ended up:

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Crank the brightness to see this aftermath photo a little better:
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I don't know what caused it, but he was not using any bms. I believe the inverter was a Grow Watt.
 
Since there is no details how the whole system is wired up it is hard to tell where the fire had started.
No BMS? No fuse or any OCP?
 
Since there is no details how the whole system is wired up it is hard to tell where the fire had started.
No BMS? No fuse or any OCP?


I don't have much information on the system, I think he had an all in one Grow Watt inverter and was using grade B 80AH cells. Bloating has been observed in these cells, for what ever that is worth.
 
Yikes! I'm starting to wonder if this LiFePO4 chemistry is as safe as it is touted to be.
 
I hope we get to see the pictures of the whole system before the accident happened and the details as to when the problem started.
May be someone drops a wrench or screwdriver or conductive material on top of that battery bank.
 
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Isn't it funny. OP says they don't know the cause or details as this was someone elses system etc...
YET Ohhh the Batteries must be a cause... Really ? Lot's of electrical gear involved, "Maybe" pets/rodents may have contributed. The love of Jumping to Conclusions and the Assumptions... Isn't everyone just a little bit sick of Chicken Little Isms yet ?
 
Wow .... getting to be way too much of this going on all of a sudden.

No BMS is a big concern, but these cells aren't supposed to start a fire.

No BMS is a big problem.
This cells can start a fire. No explosion like LiPo or NMC but cells can heat up. Also electrolyte can burn.

OK lets analize this pack, get the check list:
  • Cell compression, method? In this case cells not compressed. Not ideal but can work. Cells breathe so at 100% SoC bloat a bit and then when SoC goes down so is the bloating. No compression
  • Cells setup? In this case 5p16s setup (5 parallel and then 16 times this serial). Not ideal but can work. BMS would only saw the average V of 5 (!!!) cells. But no BMS so absolutely no protection.
  • Did you do a proper top balance of the cells ? What were your procedures, how did you do it ? No info. We can skip the rest.
  • Copper busbars on alu terminals. That is not ideal at all. Did you use noalox or carbon grease ? Terminals polished ?
  • What was charging the battery ? MPPT or PWM solar charge controller or an utility charger? Size, Type, connected solar panels number, Voc, Vmppt, Amppt ? Charging settings (bulk V, absorption V, float V, max charging current) ?
  • What was discharging the battery ? Inverter (size, type?), direct load ? Max discharging current/watt estimate ?
  • Cells electric separation? Standing on a non conductive base? Non conductive separator between the cells ?
  • Cells placement? Shed, garage, inside/outside? On the ground, on shelves, ... ? How protected from fauna (rodents, bugs) and flora ?
  • Ambient temperature? Cells and busbars temperature in high load/charge (hand test not warm is OK) ? Any extra cooling like fans ?
  • Humidity? Pipes near the battery, MPPT, inverter? Possible water, steam or condensation in the area?
  • Cable size/type to BMS and after that? Fuse after BMS, size?
  • Usage of the battery? Constantly charging, lot of time on max charge (SoC >95%)? Lot of time in minimal charge (SoC<10%)?
  • Where the battery floated? So SoC >95% and float V > 3,4-3,45V/cell ?
  • BMS is Daly. Which type, how many A? BMS still working ? Cell Volts in Daly the same as by measured with a multimeter?
  • schematic diagram of your system would be appreciated (maybe some pics from it and from battery).
 
No BMS is a big problem.
This cells can start a fire. No explosion like LiPo or NMC but cells can heat up. Also electrolyte can burn.

Could you please post your theories of how a cell can self combust on this thread?

 
Could you please post your theories of how a cell can self combust on this thread?


Already discussed in many topic. With video with professional tests and everything.

Also this is why the new topic was created: Up in smoke... learn from my mistake!
 
Already discussed in many topic. With video with professional tests and everything.

Also this is why the new topic was created: Up in smoke... learn from my mistake!
Sorry, but I searched your posts and didn't find the video you are referencing.

I did finds some videos you posted about lithium ion batteries ... but not LiFeP04. Could you please post the video again?
 
Sorry, but I searched your posts and didn't find the video you are referencing.

I did finds some videos you posted about lithium ion batteries ... but not LiFeP04. Could you please post the video again?

You can find everything in the Last Fire topic (page 8).
I put there even the BYD blade test.
And @HighTechLab his famous "double penetration" video where you can see how it glows inside the LFP case.
And after the second puncture .... the flamethrower.
 
You can find everything in the Last Fire topic (page 8).
I put there even the BYD blade test.
And @HighTechLab his famous "double penetration" video where you can see how it glows inside the LFP case.
And after the second puncture .... the flamethrower.

In the video you posted, the LTO and LFP cells swelled when overcharging, but did not catch fire like the lithium ion .... I have seen the HighTechLab video also, but I thought we were talking about thermal runaway caused by the cell ... not repeatedly stabbing it with a metal object.

We do know from that video, that if the cell is punctured the contents of the cell is flammable.
 
In the video you posted, the LTO and LFP cells swelled when overcharging, but did not catch fire like the lithium ion .... I have seen the HighTechLab video also, but I thought we were talking about thermal runaway caused by the cell ... not repeatedly stabbing it with a metal object.

We do know from that video, that if the cell is punctured the contents of the cell is flammable.

And as you know dendrites puncture the cells separator's almost the same way. That was the cause that created the needle test.
Also overcharge can cause almost the same effect on weak spots.

So LFP is safe. One of the safest lithium chemistry (only LTO is safer).
But because of the high energy density and the flammable electrolyte even that can cause fire.
 
He was so proud of his new 48v parallel series configuration. Charging the cells up...
View attachment 60059

Although not likely related to cause of fire, I would have alternated the stitch from one side to the other for each 5p of cells. Better balancing of current per cell that way.

Series charging without BMS could easily have bloated cells to the point of ripping the terminals out of them. That might pull a conductor loose, causing an arc for ignition.
The overcharging videos we watched had wires to a single cell, where that wouldn't occur, so they just vented.
 
LFP is safe. The haphazard way some people use the technology is what's not safe. A 5p16s battery is like playing Russian Roulette. A 5p16s battery without a BMS is like playing Russian Roulette with a bullet in all six cylinders! Murphy never sleeps.
Why?
 
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