Need help Figuring this FIRE out!

[Juan Gonzales]

Hi Guys
Im new here, and this has been though to post. be lenient..

A few months ago I made a DIY Battery Golf car Replacement for a friend.
Here are the Specs:

3 X 48v 20ah
16S2P
A123 LFP 3.2v 20Ah Cells
Interconnect was done with screws
80v fuse at the main positive
The charger used was QuiQ, set to charger Trojan 1275.

I need help figuring out why this battery catched fire.
The only thing I know is that my friend called me 1 hr before these pictures telling be the cart would not run. like its not charging.
Asuming the charger was overcharging the batteries, these cells should not have catch fire.
I have my head scratching






This was the middle battery that did not seemed to have fire damage:



This battery also went into thermal Runaway. Thats the only damage I could find on this one.

 

[mrzed001]

It seems bad ?

Hi Guys
Im new here, and this has been though to post. be lenient..

A few months ago I made a DIY Battery Golf car Replacement for a friend.
Here are the Specs:

3 X 48v 20ah
16S2P

16s3p maybe ?

A123 LFP 3.2v 20Ah Cells
Interconnect was done with screws
80v fuse at the main positive
The charger used was QuiQ, set to charger Trojan 1275.

I just checked the cells. https://www.alibaba.com/product-detail/SUNTE-A123-3-2V-20Ah-67Ah_62466712848.html
I would not recommend pouch cells. They are too easy to damage.
Did you built this battery ?

I need help figuring out why this battery catched fire.
The only thing I know is that my friend called me 1 hr before these pictures telling be the cart would not run. like its not charging.
Asuming the charger was overcharging the batteries, these cells should not have catch fire.
I have my head scratching
View attachment 97499View attachment 97500

And this I do not understand. There are pouch cells, and at the end (top) is a big prismatic cell as I can see
That do not seem right.

View attachment 97502View attachment 97503
View attachment 97504




This was the middle battery that did not seemed to have fire damage:
View attachment 97518


This battery also went into thermal Runaway. Thats the only damage I could find on this one.
View attachment 97519

And I can not see a single BMS !

Was there a fire, or only the case melted ?

 

[Supervstech]

How were the cells protected from imbalance or over/undercharge?

Lithium NEEDS cell level protection. Without it, they fail… spectacularly.
Without a set of before pictures it will be hard to know what went wrong.

 

[A.Justice]

Did your packs have battery management systems? Li-po pouch cells without a BMS can fail to fire incredibly easily.

 

[RCinFLA]

No BMS and cardboard kindling.

LFP electrolyte will catch fire, but it is like fuel oil, high flash point temp and high vapor temp. Normally bloating occurs first which is mostly CO2 gas so when cell finally burst the CO2 gas encases the electrolyte spray keeping oxygen away from hot electrolyte.

Other Li-Ion cathode chemistries create much more oxygen within cell making them more likely to ignite electrolyte. Electrolyte is fairly similar between all Li-Ion chemistries.

Likely severely overcharged cells. All it takes is one cell to short out and its temp will cascade to other cells popping them off.

 

[Ampster]

No BMS and cardboard kindling

So it is a teaser headline, giving LFP a bad name. If I had to give it a title it would be, " Look what happened when I overcharged my battery without a BMS".

 

[mikefitz]

Having the charger set for Trojan1275 was a big mistake. These are lead acid batteries. Nominal charge and equalisation voltage are much too high for LFP.
The 123 pouch cells are specified for a maximum charge voltage of 3.60 volts, 57.6 for a 48 volt battery. The charger setting for flooded LA would have been around 59 volts with equalisation voltage around 62 volts.

A degree of care with design of the packs and correct choice of a charging system would have avoided this issue.
Hopefully nobody was hurt on this occasion.

Mike

 

[Juan Gonzales]

Hi Guys,
Thanks so much for your reply

Yes, I built the batteries for my friend.
each battery was 48v20ah 16S1P , they were in parallel.
There was fire engulfing the batteries after allot of white smoke.
They asked me if they could use the SLA Charger and I sayed yes asuming they would not pass 3.8v (knowing they could degrade faster, but asuming 0 posibility of a fire by overcharge) Obiously, I was wrong.
Thankfully, nobody was hurt. The cart was being charged outside.

I will post photos in order, (ther´s a limit of 10 per post)
These are from the most damaged battery, lets call her #1

 

[Juan Gonzales]

These are when the battery was installed:
















These are the closeup of Battery #1, the most damaged one:

 

[sunshine_eggo]

@Juan Gonzales

I hope you have learned that LFP batteries MUST have a BMS.

 

[Juan Gonzales]

Having the charger set for Trojan1275 was a big mistake. These are lead acid batteries. Nominal charge and equalisation voltage are much too high for LFP.
The 123 pouch cells are specified for a maximum charge voltage of 3.60 volts, 57.6 for a 48 volt battery. The charger setting for flooded LA would have been around 59 volts with equalisation voltage around 62 volts.

A degree of care with design of the packs and correct choice of a charging system would have avoided this issue.
Hopefully nobody was hurt on this occasion.

Mike

Hi Mike,
Thank you so much for your input.

I learned the lesson with "correct choice of a charging system"
Now I´m digging into the "A degree of care with design of the packs"

@RCinFLA your post was very helpful.

No BMS and cardboard kindling.

LFP electrolyte will catch fire, but it is like fuel oil, high flash point temp and high vapor temp. Normally bloating occurs first which is mostly CO2 gas so when cell finally burst the CO2 gas encases the electrolyte spray keeping oxygen away from hot electrolyte.

Other Li-Ion cathode chemistries create much more oxygen within cell making them more likely to ignite electrolyte. Electrolyte is fairly similar between all Li-Ion chemistries.

Likely severely overcharged cells. All it takes is one cell to short out and its temp will cascade to other cells popping them off.

In my head, that still does not explain why it catched Fire.
Do you think the cardboard was the culprit? Carboard was used in the past for LFP Cylindrical cell covering.


@sunshine_eggo
Agreed about the BMS. Well past that. want to improve the design.

 

[sunshine_eggo]

In my head, that still does not explain why it catched Fire.
Do you think the cardboard was the culprit? Carboard was used in the past for LFP Cylindrical cell covering.


Still does not explain the Fire.

You seem to have a belief that LFP will not catch fire. It absolutely will if abused. It's among the "safest" of the Lithium chemistries. It is NOT fireproof.

 

[Bob B]

If you don't fully understand the need for a BMS ... you should ask questions about that.

 

[RCinFLA]

This was the Boeing 787 airliner battery taken out in Japan. It was lithium cobalt oxide chemistry. At least the golf cart doesn't fly.

 

[Will Prowse]

The electrolyte can still combust. I like to think of LiFePO4 as safe as a stack of wood. Of course it will catch on fire if you get it hot enough. Many things will combust if you get them hot enough on this oxygen rich planet.

 

[PeSCaLo]

The electrolyte can still combust. I like to think of LiFePO4 as safe as a stack of wood. Of course it will catch on fire if you get it hot enough. Many things will combust if you get them hot enough on this oxygen rich planet.

@Will Prowse Thats a great explanation.


So since these cells are probably Second life, Which do you think was the most likely source of ignition, the electrolyte or a design issue, (connections)?

 

[HRTKD]

The middle battery received the least amount of damage most likely because it saw fewer charge amps than the outer batteries.

 

[BradCagle]

Yeah, BMS a must, and even more so a must the higher the series. It would have prevented the overcharge of the pack, and shutdown even if only a single cell was too high.

Also did you top balance before you assembled?

 

[Juan Gonzales]

Yeah, BMS a must, and even more so a must the higher the series. It would have prevented the overcharge of the pack, and shutdown even if only a single cell was too high.

Also did you top balance before you assembled?

Yes, Top balanced all cells before assembly

 

[BiduleOhm]

Which do you think was the most likely source of ignition, the electrolyte or a design issue, (connections)?

My educated guess: cell voltage imbalance because of no BMS + higher lead acid charge voltage = at least one of the cell got past well above the absolute max safe voltage (4.2 V) for LFP.