Cell fire clean-up?

[robbob2112]

The AC charger is a INTELI-POWER 9100 mod # PD9180AL.

The DC to DC charger is a Renogy 12V 50A DC to DC Battery Charger with MPPT

BTW - if it hasn't been mentioned we all appreciate you hanging your system out there so we can all learn

... it can be hard to have some dick tell you that you are doing things wrong...



Does the Renogy DC-DC charger have any way to set the cutoff voltage or is it listed in the manual....Do you have the bluetooth option so you can set the voltage profile? I see it has a Li profile, but that usually means Lithium Ion instead of LiFePO4 batteries and that can mean a less than ideal charge profile. If it will let you do 'custom' that can be better than the default Li



So here is the working theory - you are driving 5 hours - the DC-DC charger is doing its thing, but the cuttoff voltage for charging is higher than the one for the BMS or it doesn't have one and relies on the BMS to cut things off.... in any case it just keeps trying to push current into the batteries.... you other battery does its thing and cuts off the current... the burned battery tries to cut it off and in fact things it did... but at least one MOSFET is shorted and it keeps allowing current and eventually you let out the smoke.


Looked at the manual - I can't find anything in it to show the output voltage is adjustable - seems to be made for FLA batteries and that is it. This means it is never actually charging your batteres to full.... It needs to charge to 14.6v and hold there for a little while to let your cells equalize and balance.... once disconnected they will settle to 13.6......

Will defer to the egg guy on how much trouble this is in the long run.... I don't think it will actually hurt so long as it gets 14.6 from some source... like the DC-DC charger or solar panels and a MPPT.

 

[Shroom37]

The specs you list are for the PD9180. I have the PD9180AL with an output of 14.4VDC

Input: 105-130 VAC 60 Hz1300 WattsOutput: 13.6 VDC, 80 Amps(9180AL) – 14.4 VDC, 80Amps

I agree with you on no adjustment on the Renogy DC to DC cutoff voltage. I'll have to check the voltage with my meter and see exactly what it's putting out.

When I put this system together I don't remember anyone talking about the charger doing the heavy lifting in regards to not overcharging. Seems like I just thought, wrongly I guess, that the BMS took care of that.

I'll try to tear the system down tomorrow and clean up the mess. Then put something together that will get me back home.

Thank you all for your input. I've learned a lot and had many of my questions answered.

 

[robbob2112]

Ok,

The charger is for lfp batteries - charges 2 stage - 14.4 until current drop the 13.6 after that ... but seems like it never fully cuts off... or if it does the manual doesn't say.

Would be interesting to know the exact voltages it is outputting and if it turns off completely at some point.

Also ascreencap of your bms settings....

All it would take is a slightly off, 0.5, voltage from the charger to allow your issue to happen

 

[Daddy Tanuki]

so i did not bother to read all the posts, sorry busy day. but I had two (2) DALY's that had issues like this after a lightening strike. they would claim to have cut off power, but did not. the App said that charge mosfet was off, but voltage continued to flow. I was able to prove it by watching closely with a volt meter attached. the good thing is my SCC were all set to shut off at a 54 volts, and my cells were well enough balanced so that they pretty much rose together and then stopped at at the 54.4 without overshooting and damaging anything. I would bet you have a bad BMS that is still allowing charging in some fashion.

after replacing these fried BMS's I have had zero issues since then.

 

[tabascoz]

so i did not bother to read all the posts, sorry busy day. but I had two (2) DALY's that had issues like this after a lightening strike. they would claim to have cut off power, but did not. the App said that charge mosfet was off, but voltage continued to flow. I was able to prove it by watching closely with a volt meter attached. the good thing is my SCC were all set to shut off at a 54 volts, and my cells were well enough balanced so that they pretty much rose together and then stopped at at the 54.4 without overshooting and damaging anything. I would bet you have a bad BMS that is still allowing charging in some fashion.

after replacing these fried BMS's I have had zero issues since then.

Had the same issue last week with Daly. Growatt charger cutoff set to 57.6v (16s) and still two-three cells ended up with 3.78/3.80v. I'm changing the whole charge strategy and thinking about other security controls to be in place to prevent it from happening again.

 

[Daddy Tanuki]

Had the same issue last week with Daly. Growatt charger cutoff set to 57.6v (16s) and still two-three cells ended up with 3.78/3.80v. I'm changing the whole charge strategy and thinking about other security controls to be in place to prevent it from happening again.

mine were fine until the lightening strike. it was not even close to my house but I am guessing that ground current or something was high enough to mess up something delicate inside the BMS's. at the same time it toasted a charge board on my magnum.

Fixed the magnum replaced the one BMS that I knew was bad, the other two seemed OK but I was wrong almost a year later later I discovered the above. fortunately I had defense in depth. the SCC's were set low enough, and the cells were close enough in balance that none of them overcharged...

 

[Doug42]

probably not related but I have the same renogy DC/DC. Works well enough (Very annoying you can not adjust settings) but one day it fried my van vehicle battery (FLA under seat) through its function to top up vehicle bat when there is excess solar. I know this because it started hissing hydrogen. I have had limited trust since.

mine seems to default to 3.55V in CV/absorb mode.

This looks to me like the bms wires got shorted. That would do what the damage is.The bms wires may have gotten to hot from 24 hour balancing.

Cant be this because Shroom37 said disconnecting the main fuse stopped the over charge. Given that and a burned BMS, a shorted FET seems the most likely story

Great thread by the way, Im sorry for your troubles shroom, both bodily and battery, but thanks for sharing, food for thought..

@sunshine_eggo would you recommend fitting two BMS's in series? I cant think of any other way of adding redundancy to voltage protection at a cell level. I don't like the idea of relying on chargers params and balanced cells as second line of defense

Would it make sense if you were building 2 x 48V 280Ah batteries to instead of creating two separate batteries, parallel the cells in 2's and put the BMS's in series. set one with higher trigger values and the other acts as the main? might also be useful when checking your system that both BMS's are seeing the same things. Obviously max current is sacrificed but the inverter is often the bottle neck there

Or is there another way to add OVP redundancy? Or am I just wearing too many of these foil hats?

 

[sunshine_eggo]

@sunshine_eggo would you recommend fitting two BMS's in series?

No.

I cant think of any other way of adding redundancy to voltage protection at a cell level. I don't like the idea of relying on chargers params and balanced cells as second line of defense

A BMS on a properly implemented and healthy system should never engage protection in its lifetime besides initial confirmation of proper function, i.e., everybody should test that the OVP and UVP features work when commissioning a battery.

Would it make sense if you were building 2 x 48V 280Ah batteries to instead of creating two separate batteries, parallel the cells in 2's and put the BMS's in series. set one with higher trigger values and the other acts as the main? might also be useful when checking your system that both BMS's are seeing the same things. Obviously max current is sacrificed but the inverter is often the bottle neck there

Given the fact that BMS should nearly never need to work, you're talking about redundancy for a low frequency occurrence.

I can't envision what you're describing, so I can't figure out if it would work.

Or is there another way to add OVP redundancy? Or am I just wearing too many of these foil hats?

Maybe x2

 

[robbob2112]

Would it make sense if you were building 2 x 48V 280Ah batteries to instead of creating two separate batteries, parallel the cells in 2's and put the BMS's in series. set one with higher trigger values and the other acts as the main? might also be useful when checking your system that both BMS's are seeing the same things. Obviously max current is sacrificed but the inverter is often the bottle neck there

No, if you parallel cells using one BMS - i.e. 16s2p - then you loose visibility into the voltage of every cell... instead of that 2 batteries and 2 BMS is a much better choice.

And 2 BMS in series to do protection - you would have to turn off balancing on one of them or you would end up with them fighting each other... take off the tin foil hat, put it on the ground next to the crack pipe and back away slowly so as not to startle it

 

[Doug42]

put it on the ground next to the crack pipe and back away slowly

Yeah you are probably right.. keeps my ears warm though.. and I don't like littering, think of the turtles

Likely would be a Oedipus destiny scenario, get higher operating MOSFET temps on the BMS's due to double the current, next thing you know, your kids have seven toes

its just the healthy system bit that bothers me. I have done some off grid stuff for friends and I only see those systems once a year max. so I can see something going dodgy in a charger and bouncing off the BMS limit for a long time before I get eyes on it. maybe better friend training is the answer. Still would be nice to have a bullet proof setup for when trust is low.

If someone made a Self-controled fuse (SFC) rated for 200A and some simple 3.7V zener diodes as triggers, that would be an interesting product.. Just googled, not a thing, 45A x 4 maybe. but not ideal

 

[wpns]

Yeah you are probably right.. keeps my ears warm though.. and I don't like littering, think of the turtles

Likely would be a Oedipus destiny scenario, get higher operating MOSFET temps on the BMS's due to double the current, next thing you know, your kids have seven toes

its just the healthy system bit that bothers me. I have done some off grid stuff for friends and I only see those systems once a year max. so I can see something going dodgy in a charger and bouncing off the BMS limit for a long time before I get eyes on it. maybe better friend training is the answer. Still would be nice to have a bullet proof setup for when trust is low.

If someone made a Self-controled fuse (SFC) rated for 200A and some simple 3.7V zener diodes as triggers, that would be an interesting product.. Just googled, not a thing, 45A x 4 maybe. but not ideal

Look up crowbar over voltage protection, ought to be something in that space you could use to blow a fuse. 8*)