Lithium battery fires

[Greynomad]

A QUESTION OR TWO FOR T1:

It seems the media are reporting at least one lithium battery fire a week ATM.
Mainly eScooters, with a few phones for variety.

Q1: What makes eScooters so vulnerable to fire?
Is it a different chemistry?

Q2: Should we be concerned about switching AGMs to lithium in m/homes & caravans?

Q3: What variety of lithium chemistry is safest?

Q4: In the event of a fire, how do we deal with it?
Notable recently was a battery fire at an electric bus factory in Melbourne.
The fire brigade simply covered the battery with several tons of dirt and left it to burn itself out.

[Busman]

Ray, as you have specifically directed this question to T1 I will leave him to deal with it.
Sufficient to say, those of us that moved to the right variety of Liths years ago do not worry about your concerns, indeed in the last 6 months I have built and installed a 20 Kw Lithium battery for our house, have similar size in our mh.

[native pepper]

Q,1 Lithium-ion, is very volatile, burns and explodes. The reason they use it is because it's cheaper and had a better density, which I believe is changing.

Q2. not if you use lifepo4, which think they now call LFP. It's much safer and really hard to ignite, overheat or cause any problems.

Q3, It may have changed, but Lifepo4/LFP) is the safest to my knowledge and been using it for 17 years and still full capacity in my home and bus. However discovered yesterday my 120ah portable pack had just 5.8v in it. Had noticed the charge controller was showing any charge a few days ago, but put it down to cloud cover at the time. Now it seems the charge controller has failed and discharged my pack, which was a shock. So put it on my lead acid pulse charger and last night it was sitting at 12.1v, be interesting to see what it is this morning after sitting all night.

Q4, smother the fire fast, don't use water as it doesn't work, but smothering it does keep it from growing and spreading until it burns out. if you can separate the cells and remove those undamaged you have a better chance of controlling the fire. But not a recommended action as Li fires are ferocious and extremely deadly.

When we were testing different lithium chemical make ups, we had extreme trouble controlling Li-ion and Li-poly fires, but lifepo4 were extremely hard to get burning and we had to drill a hole into a cell, then light the gases coming out. It was quickly quelled by smothering the cell and it didn't restart once un smothered. But li-ion and li-poly did restart and had to be smothered and saturated with water to reduce the heat. Strangely the lifepo4 wasn't that hot, only around the drill hole, but the others couldn't be touched until the next day and had to be covered the entire time until they cooled down. Even then didn't trust them so we buried them for a week to make sure they had stopped reacting.

Terry may reply differently and will certainly be able to provide the technical aspects of the questions, but thought our experience around 18 years ago may help by giving a different take on it. My late mate was certainly into experimentation and sometime felt we needed a nuclear bunker to stay safe, but to be honest, we never had a bad outcome and Slow hand was a stickler for safety. Many time asked him if he had yank genetics, as he loved to blow things up to find out what happened and how it worked.

Haven't blown up anything since his demise, got my blow up kicks on active service and helping my grandfather remove tree stumps with super and diesel in jam cans, plus during my building career. Had to get an explosive licence when in the building game, we used plastics to put in sewage and waste water pipes in rock on some sites and laid explosives for other builders on the estate and other places for them.

Remember one occasion, we used a bit to much in a trench only 1m from the side of the house, I put in 1/3 stick in each hole and my mate half sticks and it cleared the houses each side of us of tradies in seconds, knocking out a couple of windows. Especially the plumber who was working in the bathroom right beside the trench who was my brother in law at the time, he nearly had a heart attack was really pissed off, shook the house so bad he ended up on the floor outside the bathroom. But we couldn't stop laughing and took him to the pub for lunch. Don't think the others on the estate took any notice of our siren, flags and call out were going to let off a charge.They had got used to us clearing rock, but after that day they cleared out when anyone saw us opening the explosive trailer. We changed our tactics, so we made sure we knew exactly what was put in each drill hole. Still smile about it, especially seeing a mat hanging of the high transmission lines and white faced tradies shaking like leaves.

[T1 Terry]

A QUESTION OR TWO FOR T1:

It seems the media are reporting at least one lithium battery fire a week ATM.
Mainly eScooters, with a few phones for variety.

Q1: What makes eScooters so vulnerable to fire?
Is it a different chemistry?

The first thing to etch into the memory is, all lithium chemistry cells generate heat internally if the cell voltage goes below or above their safe working voltage.

The next thing is some lithium chemistries can generate oxygen when heated past a safe range, LiFeP04 or easier remembered as lithium ferrous cells or LFP, lithium titanate or LTO are the exceptions, they can not produce oxygen internally so require oxygen from the air outside the battery case. This might help a bit, https://lithiumhub.com/explaining-lithi ... emistries/ look at the radar charts, the benefits v the drawbacks of different lithium chemistries can be easily visualised and a judgement call regarding the priorities can easily be made ....

One thing stands out, LiPo (lithium polymer) doesn't seem to appears on these type of charts ...... they are often referred to as "hand grenade" batteries, they go bang with very little provocation.

The e Scooters use the cheapest and most energy dense, therefore lightest, cells to build their battery ..... LiPo https://en.wikipedia.org/wiki/Lithium_p ... )%20(PMMA) are synonymous with hobby model planes and fires.
The cause if operating a cell outside the safe voltage range, in these cells, 2.7v fully discharged and 4.2v fully charged.
Because they are built to a price, either no Battery Management System or very poor quality BMS modules are used. A good quality BMS will monitor individual cell voltage full time and disconnect the load, if a low voltage cell is detected, or the charger if a high voltage cell is detected.
They also use cell balancing known as active balancing where the cells are each connected to either a capacitor or an induction coil https://www.sciencedirect.com/topics/ea ... e%20losses. are used to soak up some of the capacity from the cell until the voltage is equal between the cell and the storage device. Then all the storage devices (capacitors or induction coils) are linked together so the capacity and voltage in each unit is equal, then it reconnects to the cell it is looking after. If the storage device has a high voltage than the cell, it discharges its stored capacity into the cell till the voltages are equal, if the storage device is now a lower voltage than the cell, it again absorbs some of the cells capacity until the voltage is equal .... then the cycle repeats, sometimes multiple times a second, until the high voltage cells have moved their excess capacity to the low voltage cells. At this point the battery is considered to be balanced.

The cheap and nasty BMS modules simply look at the over all voltage of the whole group of series connected cells and use a resistor to "burn off" any excess capacity that is causing a high cell voltage. The load application is tripped when the cell meets a certain voltage threshold, often higher than the safe maximum voltage for the cell, and they rely on this crude method of cell balancing to keep all the cells at or below the safe maximum voltage. A resistor gets hot the more energy it burns, this is basically how an electric kettle or bar heater works, just a wire resistor load across the supply. This means only a small resistor can be used without additional means of removing that heat, generally in the range of 0.005 amps ... bugger all if the charger is trying to push in 5 amps and there is nothing to turn it off.

They then mount this nasty package inside the plastic case that hold all the cells in an easy to handle unit. There is no method of cooling the cells or the resistors being used to balance the cells, so heat builds up.

As I mentioned in the start of this ramble, take a cell outside its safe operating voltage range and it will produce heat. LiPo is the worst for oxygen generation when the get hot, but anything with cobalt in the mix is also very susceptible to this problem. Keep the cell voltages stable and within the safe range and cool the cells, and a battery fire is very unlikely, more likely a short circuit outside the battery drags the internal voltage of the battery below the safe threshold, heat is generated, if it is a chemistry that self generates oxygen (lead acid is included in this group) them an explosion and fire will result.
A fuse close to the battery positive terminal, capable of extinguishing a DC arc at the system voltage, with a rupturing capacity within the safe max discharge limits of any cell within the battery, and the external short causing a battery fire is eliminated ..... cell voltage and therefore cell temperature is critical to the safe and long cycle life of a lithium chemistry battery .....

T1 Terry

[Swisslulu]

We first met T1 and Margaret at the UWE Kerang in 2012 - our first trip in our Kedron caravan. We were so impressed with T1s lithium presentation that Erich decided this was the future. Over the next many months and under T1s guidance, Erich built a 100aH LIFEPO4 battery to install in our LC 200 series to power a 38 litre Engel fridge. That battery is still serving us well today and so is the fridge (with some TLC by BobnBev in 2018). In fact, it is currently in the rear of our flat towed Suzuki GV. It does require a bit more monitoring these days (cell balancing) but still does the job.

In 2013 at Muckleford, the 3 AGMs in the Kedron were replaced with 200aH Lifepo4, built and installed by T1. We sold that van in 2014 and installed 400aH on a fridge slide in the new to us van, again guided by T1. In 2020, we switched to a MH and, due to the complexity of the install, we ventured to Mannum for T1 to install 400aH Lifepo4 and 840 w solar plus assorted inverters, chargers etc. A mad run home to Qld due to Covid but all is still functioning as it should.

We are now heading south and hoping to catch up with the usual suspects in SA. That is after a windscreen replacement having been rocked by a truck south of Moree today! Hoping for replacement in Ballarat next week.

[T1 Terry]

Q2: Should we be concerned about switching AGMs to lithium in m/homes & caravans?

The "powers that be" have deemed anything with lithium in the chemical make up to be a ticking time bomb .... yet it's fine to put them under the house or certain brand name, mounted on an inside wall as a feature
By reading the first instalment of these rambling, anyone with the ability to think can see that not all lithium chemical combinations risk an explosion or internal fire, seems the makers of these rules lack such a skill or rushed through a band aid "solution" to the scare campaign generated by those with vested interests or in search of the next sensational headline ....

The AS/NZS3001.2:2022 standards and design rules state that any type of RV with lithium batteries installed after 18/11/23 can not be installed in any "living" area and must be installed outside the RV. This adds problems that the clever minds never considered. The red dust often experienced in some states is powdered iron oxide, add water and it forms a conductive electrical path, pass big current through this electrical path, and lithium batteries are excellent at delivering big current for long periods, it creates a sort of pig iron that creates a short circuit across the terminals. This effect is common to all types of battery, lead acid batteries just suddenly fail where they were working fine the day before, lithium batteries turn that short circuit into a big resistor, get real hot and melt their way into the plastic case of the battery.
Da Pope was a regular member here for some time and they experienced exactly this demise of a number of the cells in their battery, but a quick sort through and a suitable battery built from the none damaged cells had them up and running again. I had a few of those melted top cells at the workshop for a "show and tell" display, unfortunately they are no more along with all the "show and tell" items that clearly demonstrated what shouldn't be done.

Now add to the mix, these drop in lithium batteries, the voltage between the two exposed terminals is 13.8v, not 3.4v that caused the cell tops of the effected battery to melt, I wouldn't want that happening under the wooden floor of my RV .......

About the only way I would feel was "safe" for mounting lithium batteries outside the RV would be in a "boot" with a filter on the cooling air intake (to remove the red dust) and louvered vents to the outside to keep the rain out while letting the heated air from the inverter/s and charger/s in an attempt to control the savage summer temps and keep the equipment functioning ... they all shut down when they get hot, that mega expensive made in Aust product, more than most, Australia is not the climate for non fan cooled electronics, in fact, advances in thermal management are already required in some areas, you can't keep electronics below 40*C in an environment that is 50*C in still air in the shade .......

I've now retired from the RV and off grid battery installation business, only having the concrete slab where the workshop and equipment once was will do that to you, so, good luck to those still in the industry still doing installations, they'll need it.

T1 Terry

[T1 Terry]

Q4: In the event of a fire, how do we deal with it?
Notable recently was a battery fire at an electric bus factory in Melbourne.
The fire brigade simply covered the battery with several tons of dirt and left it to burn itself out.

That method works, a bucket or buckets of sand work the best. The sand melts in the heat to form glass, affectively sealing the fire inside, more sand acts as a heat barrier, after that cooling water sprinkled over the sand will gradually remove the heat .... once the chemical brew is cooled, it won't produce more oxygen and the internal battery fire will go out.

Don't think for a minute that lead acid batteries are safe from this fire bomb situation, cell over voltage or over current loaded become electrolysers, the perfect mix of hydrogen and oxygen to create a mega bang and fire ..... some might remember back to the "Pulsar" sandwich plate batteries and the internal shorts blowing guards and bonnets off car the moment the starter was engaged .... with the lead acid batteries mounted under the bed, can you imagine the wake up call that would give you if the other half got up early, switched the inverter on and made a coffee or boiled the kettle ... and a short circuit inside the battery occurred Yet, the "powers that be" still consider that to be a safe place to mount lead acid batteries

T1 Terry

[Greynomad]

T1,
A thought.
In your ideal installation, wouldn’t the boot require a filter on the louvres to remove red dust in the event that air would take the easiest route in to cool the battery?

[T1 Terry]

T1,
A thought.
In your ideal installation, wouldn’t the boot require a filter on the louvres to remove red dust in the event that air would take the easiest route in to cool the battery?

Yes, either the bin has an exhaust fan or the louvred hot air outlets have fans, wired to the fans for the inverter so they turn on when the inverter gets hot, or to a thermostat mounted on a piece of heatsink on the top of the bin to sense the heat generated by the DC to DC charger and/or the solar regulator. This is a must in every installation, no matter if it's inside the living area or inside a bin, the electronics should never be mounted out in the exposed environment, the moisture and dust will kill them if the mud wasps don't get them first .... ants love them as well, a nice warm environment ...

T1 Terry

[Greynomad]

Thanks for your comprehensive answers.
I’ll be looking more closely at batteries in RVs now.