When we think of lithium battery fires, our mind normally jumps to battery-powered EVs smoldering on the highway. However, in a rare chain of events, lithium cells nearly led to the destruction of a beautiful classic Mazda in Pennsylvania last week.
On March 25, volunteers of the Lancaster Township Fire Department (LTFD) responded to a car fire at 8:12 PM, concerning a red 1982 Mazda RX-7 that had caught ablaze. The vehicle had been parked inside a garage, with the battery hooked up to a trickle charger, prior to ignition. Upon detecting a burning smell, the wife of the owner found the garage full of smoke and called 911.
The owner and his wife were able to quickly disconnect the battery, and push the rotary sportscar free of the garage. The well-equipped owner then fought the blaze in the car’s trunk with a pair of dry-chemical extinguishers. Fire crews then arrived, and followed up with a heavy dose of water. And yet, the car continued to smolder—with firefighters soon learning the reason. As is so often the case, an angry lithium battery was at play.
As a combustion-powered vehicle, one wouldn’t expect a Mazda RX-7 from the early 1980s to feature a lithium-ion battery. However, these cells aren’t just used in battery-electric EVs. They have become increasingly popular as replacements for traditional 12-volt lead-acid starter batteries. The reasons behind this are straightforward enough—the greater energy density of lithium-ion cells allows you to fit a lighter, more compact starter battery.
However, this comes with a tradeoff. Lithium-ion cells are more temperamental when it comes to charging—treat them incorrectly, and they will readily fail or, in extreme cases, catch fire. Physical damage or improper manufacturing can also cause a so-called thermal runaway event, where a chemical reaction in the battery releases excess heat that self-sustains to the point of violent combustion. In the event these batteries do burst into flames, they can be very difficult to extinguish, as the failed cells tend to keep producing heat that reignites the battery over and over again – even hours or days after being extinguished.
In the case of the stricken RX-7, firefighters were able to remove the battery from the vehicle. It continued to burn post-removal, with firefighters cooling the battery and continuing to monitor its temperature to avoid any chance of surprise reignition.
There are some interesting side details in the firefighter’s report on Facebook. The responders noted the vehicle “contained an elaborate sound system” in the trunk, where the battery was located and where the fire broke out. Photos also show a large gas bottle in the rear along with what appears to be a small compressor.
“Firefighters determined that the failure of the lithium-ion battery caused the fire in the vehicle,” read a statement on Facebook from the Lancaster Township Fire Department. According to LTFD, the owner also “expressed his disappointment with the battery that failed, noting that this was the second time the vehicle had caught fire.”
Notably, according to the battery’s spec sheet, this 12-volt starter battery does not have a Battery Management System (BMS). A BMS is a common inclusion on lithium-ion packs, used to monitor individual cell voltages to ensure they remain balanced, as well as prevent against over- or under-charge events that can permanently damage the battery.
In any case, the vehicle was lucky to survive its ordeal. Thankfully, damage was largely confined to the trunk, and the RX-7 and its gorgeous Wankel engine should live to see another day. The owner has been restoring the vehicle over 17 years, and has often taken it out to shows – we might hope that after some repair, it will be out gleaming in public once again.
Overall, this story is a good reminder that you don’t have to own an EV to suffer a dangerous lithium-ion fire. Even if you just own an E-scooter, or a regular car with a lithium-ion battery, you could end up in a situation like this one.
It’s important to always ensure lithium-ion cells are charged safely, and that any related wiring is properly maintained to avoid dangerous short circuits that could cause a thermal runaway event. In the case of a fire, it’s important to remember that cells can reignite even after they appear to have been extinguished.
There is a lot of fear and uncertainty around lithium-ion cells; we’ve seen EVs banned from transport ships and even Teslas burning underwater. Ultimately, though, it’s worth remembering that ICE cars tend to catch fire more often than EVs anyway. Plus, fire departments do have the equipment to deal with these situations, and do so on a regular basis. The trick is to work safely and be prepared, without unnecessarily worrying about what is fundamentally a very useful battery technology.
Image credits: Lancaster Township Fire Department, Limitless Lithium, Amazon
I have an Antigravity Li-ion battery.
But… They have a pretty sophisticated BMS, with a low voltage shutoff to protect the battery and enable an emergency start feature. I also have the charger meant for Li-ion batteries, which I don’t put on that often.
This guy was playing with fire!
…twice apparently.
Mmm hot taco.
He may be able to restore the damage visually but good luck getting rid of the smoke/burnt smell embedded in the fabrics.
Entropy is a b**ch and some things just can’t be undone.
Also, it was the second time it caught on fire?! Mmmmmmmk
“with the battery hooked up to a trickle charger, prior to ignition. “
I’m guessing that’s the root issue right there. You don’t trickle charge Lithium batteries. And you don’t want to keep them at 100% while unused.
For details on how a Lithium battery should be charged, have a look at this link
https://batteryuniversity.com/article/bu-409-charging-lithium-ion
And specifically in that link is the statement:
“Li-ion cannot absorb overcharge. When fully charged, the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium and compromise safety. To minimize stress, keep the lithium-ion battery at the peak cut-off as short as possible.”
When storing lithium batteries, ideally you only want them to be at around 40-50% charge
That’s the part that stuck out to me, too. I always store my lithium motorcycle battery with a partial discharge. I also followed the manufacturer’s instructions and got a charger meant to work with lithium batteries. Overcharging a lithium battery is no joke!
Edit: Also, that battery doesn’t have a BMS, which, yikes!
No BMS? Well that’s a recipe for a thermal event.
Ya think? Na, that will never happen!
Whoa, no BMS in an automotive li-ion 12 volt? No wonder it flamed up.
I’ve always been a huge fan of lithium batteries for everyday use, and I’ve heard these charging recommendations a few times.
Personally I’ve always fully charged my lithium ion batteries before storage, and this has led to 0 failures in 16 years and more than a dozen power tool batteries and even more toy batteries from different brands.
The only failure I’ve ever had was with a few months old lipo battery that I stored at 1/2 charge.
I will keep doing what I’m doing, although I’m sure the recommendations are correct, because you can’t practically store your power tool and lawn batteries at 40% charge.
Buys lightweight sports car. Buys lithium battery to save weight. Fills trunk with amps and speakers.
I was thinking along the same lines. On a motorcycle or e-bike, or even a stripped out track car, the reduced weight would have benefits. But for a regular car, with all its features intact, I don’t see much of a point beyond a custom job that requires the battery to be relocated to a smaller space. The weight savings are negligible.
And probably used a trickle charger meant for lead-acid batteries.
My guess is that because of the system there was a draw on the battery. So they they bought Li not for weight but for more capacity. Then when it still drained the battery they hooked it to a trickle charger.
So what I’m hearing is keep my nimh traction batteries and lead acid starter in my Ranger, got it thanks.
This is precisely why my Prius is still using NiMH and not aftermarket lithium.
Why is that amp the size of a suitcase? Do they need like 20,000 watts RMS?
FWIW, that heat sink may have helped contain the fire from further thermal runaway.
I was thinking about just this reading that post the other day about aftermarket Leaf batteries. 900 lbs of lithium cells from Alibaba, DIY installed: what could possibly go wrong?
Thank God for the new tariffs.
That will save us from having the cash to purchase defective shit from Amazon and China as well.
A beautiful win for us all.
Very unfortunate for the owner. Hopefully the damage isn’t so bad that the car can’t be repaired.
I have not been able to trust of justify aftermarket lithium car batteries yet. I used to spend time around a facility that housed hundreds of collector cars. The ones that had lithium batteries were always a PITA, and that’s in addition to their history of increased risk of fire.
I can’t wait for solid state batts to reach mainstream. Even if they offer no extra capacity, the resistance to thermal runaway alone will be a boon for automotive.
That’s a very sweet RX-7, even if I’m 30+ years past the point where I could dig the ground effects kit.
Given the car/upgrades, I gotta assume this owner knew enough to use the right kind of trickle charger on the lithium battery. I’ve got a few different trickle chargers/jump starters in the house, but they’re all for standard lead-acid battery chemistry (some even say so explicitly on the unit, and some don’t). I’d be a bit curious as to WHY the car was even ON a trickle charger: I’ve got a lithium battery jump box/battery pack thingy that I keep in my old Volvo (w/a 8-9 year old lead acid battery) and going by the % of charge display on it, its state-of-charge decreases very slowly when idle, even after months of just sitting around in the back seat. I’d have thought a lithium car battery (that replaced the original lead acid one) would also be good at sitting around w/o draining too much, perhaps rendering a trickle charger unnecessary altogether.
Anyway, I’m relieved the whole Mazda didn’t get cooked. Sure, it looks like a mess, but hardly unsalvageable. There are only a finite number of RX-7s left in the world, and IMO we can’t afford to lose more of them.
The low self-discharge of Li batteries has been a game-changer for me. Now I can pick up a random power tool that’s been sitting for weeks and it just works. I can walk out to a bike that’s been ignored all winter, hit the starter button and it just turns over. About the only thing that compares is the low self-discharge NiMH batteries like IKEA sells.
I’m going to guess the trickle charger was for a mystery current drain.
you beat me to it. Car audio on that scale makes me think there could have been a current draw.
I’ve been signing the praise of Sanyo Eneloop since the dawn of Mankind. I haven’t bought any single-use battery for decades.
“Sanyo Eneloop”
Panasonic, not Sanyo
Panasonic bought Sanyo…
So…. this is VERY relevant to my job, and previous jobs.
Just a quick look at the specs on the battery, and one single thing stood out for me:
This battery doesn’t have a BMS…
Take that and let’s assume that the quality of the LFP cells is from a bargain basement supplier (think the opposite of a CATL, BYD, etc..)
On top of both of those points, this was hooked up to a trickle charger. Was the trickle charger rated for this battery? Was the battery rated for the trickle charger?
Recipe for failure
No BMS? Oof. So no thermal, current, or over/undercharge protection and no cell balancing.
What could possibly go wrong?
If there’s no BMS, even the very best LiPO cells won’t prevent the battery to go kaboom.
True!
This is why those knockoff Leaf batteries would concern me. Using good cells doesn’t help if your shady electronics are not up to snuff.
Would the BMS be integrated in the battery or external?
Usually yes, internal to the battery. Sometimes they are external though.
How can you tell if it has a BMS? Is there something physical on the battery to look for or just going off a spec sheet?
I just googled the spec sheet, here:
https://limitlesslithium.com/products/retro-pro-56-limitless-lithium.html?srsltid=AfmBOorisVaAtc7lbWLH9EW8e6FnK4cFmhIzF75vnyr875Z7ini4C1e7
If it were me? I’d just stick with lead-acid for 12v, and on a classic/customized car… I’d put in a kill switch. Jay Leno recommends this to car collectors… because there are other way to start a fire in older cars that isn’t the battery’s fault.
Spec sheet. The only batteries I buy have been tested by Will Prowse at Mobile Solar.
Lewin kindly linked to the spec sheet in the picture’s caption.
Having no BMS can actually be a safe and reliable configuration if the configuration is a single string of LFP, all cells initially bottom balanced to 0.001V of each other before use, with consistent interconnects that aren’t allowed come loose, and a charger that will always shut off before overcharging the pack.
Jack Rickard of evtv.me has proven this, some of his EVs using this configuration which have gotten 6-digit pack mileage. He was using CALB CA100FI and CA180FI cells.
This design trick will not work for other lithium chemistries and will not work if the LFP is arranged in 2 or more parallel strings. If the batteries are not initially bottom balanced closely before use, you will have problems.
Unlike LiIon, LFP typically doesn’t catch fire when it goes into thermal runaway, but belches out toxic smoke and melts.
In virtually all other cases for lithium-based chemistries, you absolutely do need a BMS.
To be honest I’d be even more scared to go BMS-less with LFP. The voltage/capacity curve for LFP isn’t that accurate when the cells are in mid-range capacity-wise. Over time unless the voltage curve is calibrated I wouldn’t trust the capacity readout all that much.
In other words, Nova King way I’d touch LiPO and LFP without some sort of cell voltage monitoring and balancing mechanism.
I use some fairly high capacity packs for RC helicopters and charge them with multi-port chargers. Once I plugged the balancing lead into the wrong charger port. When I walked by I saw the voltage read-out at 4.25V/cell, freaked out, unplugged the pack, and left the pack outside the house for an hour in case it goes kablamo. Fortunately no damage was done.
I usually charge to 4.18V for cell longevity.
Decade old 20.8 kWh pack of CALB CA100FI in my GT6 conversion. All cells are still within 0.001V of each other.
Jack Rickard used BMSs in CALB packs as well, and gave them the name “Battery Murdering Systems” for a bunch of valid reasons related to premature pack death…
Nice!
I’m kind of a wimp when it comes to Li-based power source.
My RC heli can drain a 250Wh 12S pack in less than two minutes (but my flying skills cant.) That’s over 10HP. A comparable heli with glow engine peaks at maybe 1/3 of that.
Such power source deserves the most respect.
That’s enough “ifs” for me to never park it in a garage or structure that is attached to, or close to my house.
No BMS on an auto 12 volt li-ion battery… is negligence in the extreme. Not sure what they were thinking.
Lithium Ion needs a compatible trickle charger to prevent overcharging which can result in battery damage and potential fire. If the owner was unaware of this and used a regular trickle charger it may be the cause.
Or, based on the fact that the car has already had one fire, perhaps the owner is just a crappy/careless electrician.
Great. I replaced the lead acid battery in my motorcycle with a lithium battery. It’s directly underneath my ass.
Aftermarket seat warmer
“…noting that this was the second time the vehicle had caught fire.”
Fool me once, shame on me. Fool me twice, you can’t fool me again. I think after the first fire I’d reconsider things a bit.
Yeah, I wonder if that first fire was lithium related, or something else
Another news article on this incident said the other fire was years ago so my guess would be not.
Probably related to those massive amps overheating.
Or an oil leak from the Dorito engine.
Don’t think I’ve ever seen an RX-7 on air before, but it looks (looked) great. I hope insurance covers it and they can rebuild.
I have to wonder if the risks outweigh the benefits. How much time before insurance companies deny claims related to Li batteries when there are safer substitutes available (i.e., assumption of the risk)?