My Project Lithium Battery Caught Fire

By anyone who is not blind, delusional, biased, senile or has had one too many glasses of hateraid ol chap.

 

"YOu DOn'T knOw whO I Am, BUT bUY tHeSE DoZEn eXpeNsIVe dOODADS to Get INcreASed MPg. USE my LInk tO SAve sOme CASh."
"Okay, I bought one and it caught on fire."
"LIAR!!! Tell Us WHo YoU aRE!!!"

 

See my proposed action plan in post #223 in your Signal Soother Test thread.

 

@Mr. F

Follow the troll train the link to my thread where I told old chapman who I have met from the forum.

Otherwise Im not sure what kind of personal info you want to know about me or why it matters to you.

Honestly it seems like you have mental issues typing like a keyboard warrior who would never meet anyone in the first place.

 

Seriously people, get a life. My NiMh battery caught fire FFS, I posted photos of it sometime back on this forum, yet I still had some members posting it was false
I have tortured a lot of LFP cells when I was initially designing our BMS and battery systems for off grid house batteries, and they simply do not catch fire .... they vent their more volatile parts of their electrolyte, it might look like smoke, but it is actually a dense cloud of vapour that settles very quickly, but they can't actually catch fire, they do not generate their own oxygen, so any fire would require oxygen from the air outside the cell casing and something to ignite it.

It requires cobalt in the chemical make up to generate oxygen inside the cell when over heated, then you have all the requirements for a battery fire, LFP, LYP and lithium titanate do not contain cobalt, Sodium ion doesn't contain cobalt either, so no chance they will catch fire either.

Sodium ion is a cell chemistry still developing and has been over 3 to 4 yrs, there are over 700 different combinations of anode, cathode, electrolyte mixes and more still in the lab.

Even though popular social media experts seem to consider the electrolyte is salt water, that was abandoned in the very early testing, the water breaks down and shortens the cycle life, the non active plate (anode and cathode relate to the direction of electron flow, charging or discharging) is not graphite, hard carbon and graphene are popular at the moment, but CATL is already on its second commercial version, so it's way too early to say what the ultimate combination will be .... but you can bet it will come out of China ... they are just so far ahead of the game in battery technology now the rest of the world would be some what foolish to even attempt to play catch up ......
Will sodium ion be the chemistry type to replace lithium ion ..... who knows, it will be the one that can charge the fastest, discharge at a consistent current rate from 100% SOC to 5% SOC without serious degradation of capacity or internal resistance over 10,000 cycles (that equates to 3 cycles from 100% to 5% every day for 10 yrs) yet remain cost effective .... sodium ion is up there with the best of them at the moment ......

T1 Terry

 

@T1 Terry
You sound like an intelligent person, which is refreshing. Thank you for taking the time to respond to my accusations.
Looking forward to continuing this conversation with another rationale adult.

A key difference is that you designed a BMS into your LFP system, whereas NexPower did not design a BMS into their LFP packs. So then all it takes is one cell overcharging and then it's game over. They added insult to injury by later creating the "Signal Soother", which masks cell failures to the one remaining OEM component that might otherwise detect said failure.

Would your company allow you to sell an LFP product that only monitors stack voltage every ten cells (e.g. 1-, 10+, 20+, 30+, etc)? Do you agree that is a recipe for disaster?

Please search youtube for several counterexamples. While fires are less common with LFP cells, they can and do happen, both directly & indirectly (e.g. due to heat spread into nearby combustibles). I have a few addenda below.

Yes, you have described the most common LFP failure mode. However, while LFP batteries are vastly less fire-prone than other lithium chemistries (e.g. NMC), they're not completely immune to fire.

I agree. Specifically, LiCoO2 is the primary catalyst for self-sustained oxygen generation in 'standard' lithium cells. The same precursor also decomposes into carbon monoxide and lithium oxide (the white crystalline solid that gets deposited on nearby surfaces during thermal runaway).

However, I must clarify that while LFP cells aren't self-sustaining during a fire, they are still capable of burning (i.e. producing flames during a thermal event). Yes, non-LFP lithium is more likely to run away, but the fact remains that LFP cells can burn if not properly monitored. Please consult your references online for numerous examples.

Taking a step back, do we really expect customers to care whether or not flames are emitted during an LFP thermal event? Either way they're going to have a bad experience, which is easily preventable by adding a BMS. Obviously having the car 'only' fill with smoke is a better outcome than also having it also burn to the ground... but are we really ok with a product that doesn't make even a passing attempt at preventing the thermal event from occurring?

Whether or not the cells sustain fire during a thermal event, engineering best practices require LFP systems to have a properly designed BMS system. That's why you designed a BMS for your system, right? The fact is NexPower chose not to add a BMS to their LFP products, which is unsafe because it leads to thermal events (whether or not there are flames).

I agree, and will reiterate that only a few sodium chemistries will ultimately 'win' in the long run... time will tell who picked the right horse. Five years from now we'll likely have a similar conversation regarding the "NMC vs "MnO" debate ten years ago.

Yes, I agree, and time will tell. Two additional deliverable are volumetric & gravimetric energy density... sodium has a long way to go there... if it can catch up, it will leave lithium in the dust.

 

No sure how up-to-date you are on the latest sodium ion developments, but testing shows the charge faster with less heat generated and discharge much faster with less heat generated and very little voltage drop ..... but it is a tad more linear than LFP, so that needs to be factored in. Their real advantage is the apparent zero damage to being discharged to 0V, I'm not willing to attempt reverse charging them yet, where a cell drops to 0V but those either side still hold voltage and capacity, so the current is dragged through the 0V cell effectively reverse charging it .... fatal for LFP cells, I'll wait until I finish torture testing these cells before I subject them to that though, just in case :lol:

I've had LYP cells held at 4.5v till all the electrolyte had boiled off (they won't go over that voltage while they can boil off their electrolyte) but after that, the voltage is meaningless, there is nothing linking the plates together, the heat becomes so high the plastic separator sheet melts and seals each plate.

Care to link an LFP fire video that wasn't caused by aluminium cell cases touching one another or an outside metal component linked to the battery negative?
Unfortunately, I no longer have the time laps video of a cell on charge with a gas flame mounted 50mm above the vent ... it actually blew the flame out, second test was 150mm above the vent and the vapour stream can clearly be seen below the flame and a very weak flame above it, still not enough oxygen mixed with the vapour to create a decent flame. At $200 per cell, two was enough to sacrifice ....

You mention a vehicle filling with smoke, that indicates combustion, so not the correct term I believe, it is vapour and smells so sickly sweet that no one could stay seated in the vehicle well before it built up to cloud stage ...... from that one would assume the event of the vehicle filling with a cloud of vapour would not happen.

As far as batch testing cells, you do realise the Toyota NiMh module system in the genuine battery only voltage tests in batches of 12 cells (6 cells per module and 2 module testing) but I agree, every cell should be voltage monitored and a charging/discharging cut triggered when the upper and lower extremes are met .... but not even Tesla monitor that closely .... MG does, but I see they aren't part of the US market ......

Let's look at a battery pack that monitors 4 cells in each group, take a cell above 4v or below 1v and the safe range for the other 3 cells plus the over voltage or under voltage cell adds up to a voltage that could be monitored ... not that I consider that to be an optimal arrangement, but enough to avoid thermal runaway .... so safety level monitoring, not, not optimal cycle life monitoring .....

I consider that proper cell voltage monitoring, whether a single cell or multiple cells in parallel is the optimal method and temperature monitoring is not required, but if series group monitoring is used, them temp sensing is a must. The next essential thing is proper cell balancing, not milli amps but 5 amps min that switches on at 150mv out of balance and off at 5mv, so the unit isn't wasting battery capacity nit picking that last bit or trying to balance unnecessarily because different internal resistances were causing the voltage differential, not actually capacity related ... a hard yet not impossible task for Prius 228v battery, 16 groups x 4 cells with an average voltage of 3.56 volts. The nom. voltage for a traction pack is 201v/16 groups/4 cells = 3.1v per cell, the sodium ion can handle 4v high to almost 0v low, 3 x 4v = 12v x 16 = 192v if every group lost a cell yet it attempted to fully charge the battery ..... it wouldn't be that hard to set a min and max voltage regarding charging and discharging ..... better to monitor every cell, but .....

T1 Terry