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Melted Wiring in GSL Battery - Any idea what went wrong here?

Leaking cells do not cause fusing of BMS voltage sense wires, there is no sensible connection between these events.
Burned wires and burn marks on PCBs is inevitably a BMS design failure, some failure mode they did not consider when designing cell sensing and balancing circuits. In a normal BMS design those circuits are high enough impedance to prevent wire melting, so melted wires are certainly caused by a BMS failure. And seeing how there are multiple similar failures happening at different customer's systems just confirms a major BMS design fault.
It looks like people you are talking to are trying to shift blame from BMS to something else.
 
Also, when cells are overcharged to the point of leaking there would be other evidence, such as unmistakable, overbearing smell of electrolyte, popped pressure valves, signs of flowing and drying electrolyte, puffing of exposed cell surfaces, etc etc. Cell voltages would not measure normal values and would be all over the place.
 
electric said:
Leaking cells do not cause fusing of BMS voltage sense wires, there is no sensible connection between these events.
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There absolutely is a connection if the leaking electrolyte dribbles down or drips onto the BMS balance wires. It is very common especially in motor vehicles.
Also these Seplos BMS have been around for several years and I have never ever seen this type of problem with them mentioned before so liquid intrusion by whatever means and the pictures we have seen in this thread is the most obvious cause of the problem.
 
weirded said:
Based on his experience, the issue is caused by seepage from the battery cells, not external moisture. Apparently, the Flexnet DC component that’s part of my system adjusts the charge currents and voltages based on lead acid batteries, which creates conditions that are problematic for the LFP batteries and accelerate this issue. He recommended simply removing that component from the system.
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Can we confirm & verify the Flexnet DC component "adjusts charging based on Lead Acid" parameters?
Is there no control to change how the Flexnet operates for use with batteries Other than L-Acid?
 
OffGridForGood said:
Can we confirm & verify the Flexnet DC component "adjusts charging based on Lead Acid" parameters?
Is there no control to change how the Flexnet operates for use with batteries Other than L-Acid?
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According to Dave, there is essentially no way to observe or control this through the Outback software. He has done a number of systems with Outback and these batteries and strongly recommends simply removing the FlexNet.
 
weirded said:
According to Dave, there is essentially no way to observe or control this through the Outback software. He has done a number of systems with Outback and these batteries and strongly recommends simply removing the FlexNet.
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Just for my understanding, this flexnet component is specific to outback ?
 
weirded said:
According to Dave, there is essentially no way to observe or control this through the Outback software. He has done a number of systems with Outback and these batteries and strongly recommends simply removing the FlexNet.
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In other words, the Flexnet needs a HUGE warrning label applied to it that reads "For use with Lead-Acid Batteries Only" ?
So this type of failure doesn't happen to anyone else?
 
Sounds like a crappy BMS - it should protect the cells even if the charging source was doing something funky. That's its job. YOU HAD ONE JOB. Dangit.
 
SparkyJJO said:
Sounds like a crappy BMS - it should protect the cells even if the charging source was doing something funky. That's its job. YOU HAD ONE JOB. Dangit.
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Yet 10.000's of these are around and not one ( that I heard off ) was crappy.
I personally manage about 30 or so, a friend has uses them for the telecom / datacenter provider he works for, has about 1500 in service and he hasn't any of this..
What he did seem was a batch during Covid where a resistor was bad and had to be replaced

Still of the opinion that :
1 either the OEM took short cuts OR
2 cells were crappy to begin with, leaked, cause issues
 
My point was if the theory that the flexnet was causing issues was true, then the BMS failed at its job. Why it failed is up for debate.

Reality is right now we still don't know what the cause was.
 
Quattrohead said:
There absolutely is a connection if the leaking electrolyte dribbles down or drips onto the BMS balance wires. It is very common especially in motor vehicles.
Also these Seplos BMS have been around for several years and I have never ever seen this type of problem with them mentioned before so liquid intrusion by whatever means and the pictures we have seen in this thread is the most obvious cause of the problem.
Click to expand...
It's a simple issue of better or worse conductivity, where electrolyte conductivity is much worse then pure copper, so electrolyte which forms the short between 2 wires will boil off and evaporate much faster than wire would heat up to a point of burning PVC insulation.
 
I just relooked at the photo's posted but did not reread the thread.
With the case mounted up, the cells laying on their wide side and are not standing upright ?
 
Steve_S said:
I just relooked at the photo's posted but did not reread the thread.
With the case mounted up, the cells laying on their wide side and are not standing upright ?
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Correct, if you look at the first picture at the very top in this thread you can see the cells laying on their sides, they look like low capacity cells and there are a lot of them. If they have put several cells in parallel to make up the capacity, then you lose individual cell monitoring and one cell could take a crap and you would never know it.

diysolarforum.com

Gsl battery fires

Hey we’ve had a bunch of gsl 48v 200 ah batteries fail catastrophically, balance wires overheating. Any idea why these could be doing this? We’ve had four sites with every battery burning up. They are all using seplos 200amp bms. Most are being charged to 56v with 6 min absorption. At this...
diysolarforum.com diysolarforum.com
 
electric said:
It's a simple issue of better or worse conductivity, where electrolyte conductivity is much worse then pure copper, so electrolyte which forms the short between 2 wires will boil off and evaporate much faster than wire would heat up to a point of burning PVC insulation.
Click to expand...
I don't understand the point you are trying to make. Electrical corrosion can certainly conduct enough to cause problems.
I'm 100% certain that it could be condensation but is far more likely to be cell electrolyte leakage.
It would be great if the OP could show us all the cells in one of the damaged batteries.
 
Design flaw. They stacked and clamped many cells on their flat side without compliant foam sheets between cells that would allow them to expand as they age. This puts huge forces on the cells as they crush themselves against rigid fixture which causes electrolyte leak on BMS board below. Electrolyte reacts with solder on PCB and causes conductive reaction product to short BMS voltage sense wires. These batteries need to be recalled.
gsl-batt-fail.jpg gsl-batt-fail2.jpg
 
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