LiPo fire destroyed my beach cruiser. Warning for others!

A

AussieRider

1 kW
Joined
Jul 30, 2010
Messages
358
Location
Seaford, Australia
G'day folks.
Had a disaster last night that I'd like to share as a warning for all.
I built this beach cruiser about 3 years ago. I've had great use out of it & it was my first choice when I wanted a ride or to get groceries.
I thought I'd been looking after the LiPo pack ( 2x4S, 2P ) as it had no BMS. I monitored the charging & every 5th cycle I pulled the packs out & balance charged them.
The bike was reliable and a joy to ride until last night. I'd had a great days ride & run until LVC kicked in. While charging the charger stopped with "cell voltage error".
I just reset & left it UNATTENDED as it was getting late. NEVER LEAVE CHARGING LiPoS UNATTENDED!!!
Anyhow, this is wot I found the next day..
edenburn3.jpg
the seat was still there, but it was just crispy ashes that blew away with the first breeze.
edenburn2.jpg
The batts were in the right hand pannier.
eden3burn1.jpg
Even the alloy rim melted.
edenburn4.jpg
I thought that after living with this bike for 3 years I had this LiPo care caper down pat. This proves I was wrong.
I always reckon that the best mistakes to learn from are someone elses. I hope you can take this with you and not lose your prize build.

A sad AussieRider.
 
Dude I'm glad it wasn't worse! . . . Thankyou for the documenting and warning.

Besides the good info you posted like not charging unattended, some more info could further help some that could currently have bad use habits.

What was your LVC set at for the 8s?
The lower this is set, the more chance a weak cell or two can fall dangerously low, 'wearing' on cells and posing more threat when charging.

Did you check individual cell levels before charging?
One should always do this imo (before/during/after). Limit charge current if cell/group is low but still within spec voltage. EXTREME caution with charging extremely low voltages.

Did you bulk or balance charge?
Imo, if you HAVE to balance regularly, you've got subpar cells or you're using the batteries too hard- either too much current or discharge depth or both. I think it's always a good idea to attend a charge, even if the back is bms'd.

///One more general question: What was the age of packs, and approx cycle amount?
 
Nutspecial, you made some good points.
LVC was set to 24V, that's 3V per cell. I did notice the motor slowing a little just before cutout.
The motor is only 200W to be street legal in AUS so I don't think the packs were overworked but maybe over discharged.
I checked the batteries temps after runs & after charging & they were never more than warm to the touch.
Chargers are set to 5A during CC mode. With two 6000mA packs in parallel, that's 2.5 A or about 0.5 C.
I was bulk charging. I balance charged every 5th or 6th time. Cell variation was 0.03V initial at the last balance charge.
The packs were 3 years old, the original set when I first built the bike & had about 150 cycles on them.
Maybe they were crap cells, but more importantly, if I was there like I should have been, I may have smelt something & saved my cruiser.

AussieRider.
 
Hmm! Well that's a conservative charge, though possibly not as much or debatable @ lipo cell voltages below 3.5v. I'm thinking that charging at even .5c @ levels possibly 3v or below caused a runaway. Also, I think it's advisable to never recharge when batts are noticably above ambient temp, to be safe. Also, I'm sure age/cycles works into the equation too.
Did you happen to confirm cell levels before charging? Some groups could have been well below 3v based on how they start to imbalance even at 3.3-3.5v.

I always drop charge rate way down even just below 3.5v /cell. They come up so fast even at the highly reduced amperage. That has worked to charge cells way low @ even 1 - 2v (.01c rate), though those likely shortened the reasonable service life of the pack.

Thanks again for posting. I think I can tell you feel fortunate even though the cruiser took heavy damage. If homeowners etc can't help, hopefully it's repairable. Again, even with a bms I wouldn't trust lithium, especially lipo, charged unattended.
 
Sad for what happens, I have 2 different good friends that had a serious lipo accidents here, lately, and I know what shocking that could be. Your accident is way less serious if that can be of consolation: One of them seriously damaged his RH hand (2 months to fully recover) with a big KFC due to his mistake, obviously, since He connected the RC charging plugs to the lipos first, and then kept the 2 male banana plug that goes into the Charger in his hand together, vaporizing all the metal right in contact to his palm (I have true hardcore picture of that, that I'm considering to post in the lipo disaster thread)...the other was bulk charging in his balcony a 12s lipo pack with an unproperly trimmered meanwell, but had in the small balcony also acrylic varnish, solvents and lot of flammable stuff. It was not unattended because He was in the bedroom from where you go to the balcony, but was very tired in the night and fall asleep, He lost everything but the life causing serious damage to his apartment and even to the upper floors of the building where other people lived. a neighbor guy waked him up, and in the time they was looking for an extinguisher the fire had broken the glass of the door, eaten the curtain and taken the bedroom. someone got a video of the final, spectacular, exploding fire (varnish etc.) from the front building....and I'm considering to link at it too.

That said, your strategies seems reasonably conservative and good to me, but not the LVC. If your LVC has been 3V per cell during all the 3 years/150 cycles, than, no matter of the Ch/Disch rates you uses and that you can balance even every time, those batteries have been abused, and are dangerous. I have a 3.45 LVC and always got all the promised Ah from my lipo packs.

Hope you get the bike rebuilt ASAP.
 
What voltage did you leave them at when storing? Were they all puffed the last time you checked? When I had first built my lipo turnigy 5ah pack I let it sit at full charge while not using it. After the summer each cell was puffed. After that I charged it to 3.8v for storing. Last summer I started using it again and noticed one string of cells had drained the voltage, pulled apart the pack and one of the puffed packs was split open. I since have other cells and made a second pack with them, always leave them at 3.8v storage and not a bit of puff. I also have 4 turnigy cells I have never used and sat at the 3.8v they shipped with 2 years ago and have no puff. I also had pack of $20 a cell 4ah battery space cells, these cells never puffed even when leaving them at full charge. I killed them by pushing too much current thru them but after having them for 5 years now, and after them being killed from over amp, there is still not puff at all. So now I know with cheap rc pack cells never leave at full charge. You get what you pay for, don't trust them to be a quality lithium battery solution.
 
Lucky result i think, when you think you got it all covered it bites you in the a hole complacency comes into this one with the cell error message and still charged away unattended.
Some rc chargers have a temp probe for charging that most BMS lack you can monitor individual cell voltage that BMS lack and most 18650 lithium BMS lvc cycles lipo cells to deeply, but you did not have one present so that's not to blame but you was cycling the cells down to 3v I find the absolute cutoff voltage to be around 3.4v but cells differ so i tend to use 3.5v underload and monitor the Wh used to get to 80% max never 100% deplete overtime it will kill any of the current lithium based cells.
Your storage charge of 3.8v is fine and balance charging every fifth cycle is ample enough but if you can with an aging pack do it every charge, The definitive way to check pack health is to IR test the cell and check its total Wh when discharged to 80% then add the 20% on with math if the packs appear to be slipping more than 80% of stock values no ifs or buts place them in a large bucket of salty water outside for 24hours check till cell voltages are 0V then dispose.
 
Thanks for posting that. It could have been much, much worse. It looks like the frame may be still OK and you could fix it with enough work.
 
Thanks for sharing AussieRider, well done, logically I think we only see a fraction of all the battery fires that happen because its too traumatic to share normally..

Considering your seat got barbecued into virtual oblivion I noticed that your saddle bags while also totally BBQed still hold some physical structure, is that because the saddle bags are made out of some kind of metal or leather or something? Its probably what saved the whole garage.
You lipo pack was relatively tiny being 8S2P? While we shouldn't be surprised that a pack that small could flame out that much its still an eye opener.
What were the Ah of the pack?
 
There was someone else on this forum that left there lipos charging and unintended and he for got about it and ended up burning up his garage
he was lucky his house was not burnt down and every one was OK in the house.

I my self is using Lipos and need to look at a large enough Lipo bag. Also might look at putting a smoke alarm in the bag :idea:
 
Glad you're ok. A few notes for yourself and others to avoid preventable errors such as you've described. A few small but key differences would have prevented your fire.

LiPo is mostly empty below 3.6V.
3.0V/cell LVC is too low without cell level protection. In an extreme case a single cell could be at 0V while the others are at 3.4V. This type of imbalance is likely the root cause of your issue.

Never ignore your charger warnings.
Graph discharge when possible to determine weak cells.
Use a proper meter to gauge tested capacity instead of relying on LVC.
Use cell level voltage alarms, particularly for discharge.

Good luck on your next build. On the bright side you still have your health and house. 3 years was a good long life-- time for a new setup!
 
Thanks for the kind words, support and most important for me and hopefully others, all the helpful advice. I hope to rebuild her. Beastie, the panniers were fibreglass. All that was left of the lids was the mat with a thick layer of soot. It may have contained the fire a bit. In the second & third pics you can see the melted helmet hanging from the T bar shifter.
SM, thank you for posting the pic of her in her prime. Until the rebuild though, I still have the chopper ( which was parked only a metre away! ). Could have lost it and 2 fresh out of the crate N.O.S EVT 4000s. Dumb luck. I was dumb, luck was with me.

AussieRider
 
I concur with everyone else here.

First, let me say, so sorry for your loss.
Second, as the others have stated, 3v cutoff is way too low. 3v per cell is not the point to stop running the cell. 3v is the point that cell damage occurs. I set my LV cutoff at 3.5 volts per cell and I charge up to 48.5 volts (12S pack).

I hope to see pictures of the rebuilt bike soon!

Matt
 
i think the real reason what caused the fire is the balance charger!!!

i never use balancer on BMS or charger, i told each of our cusomers, but but but i take notice of many many guys use li battery and lipo battery without BMS and use balancer for charging.

why cells will lose balance after some cycls, it is short circuit inside cell, we name that is is tiny short circuit. It is a certain physical property of each cell. There is no two same cells at all. We just choose or select some most simillar cells to build pack, after some times of charge and discharge, it aggravate the tiny short circuit, so we can see different voltage from cells, if we charge without balance the weak cell will be different with others more and more. and we should change the whole pack when we cant accept the shorter ridding range. It is this process to find which is the bad cell. It tell us do not use again and it dangerous.
But you charge with balancer inside BMS or charger, you will make different cells looks same, you will not know who is the bad one, so you charge and discharge again and again. The tiny short circuit becomes real short circuit inside cells, so it caused fire.

So do not balance cells again, guys!

The tiny circuit comes from tiny hole of plastic saperater and small thorn on the edge of anode and cathode once cutting.
 
Cryzymotor, I think some of your explanation has been lost in translation to English. Please do not take offence. I think my mistake was over discharging then not using individual cell balance charging. Also I may have damaged cells by storing partly discharge at an unknown level instead of recharging to a "storage" level. I do understand "tiny thorns" though. They are called "dendrites". In my early RC days with NiCads, we would revive old cells by burning the dendrites off with short bursts of 12V in to 1.2 volt cells. Crazy? Dangerous? You bet! There wasn't much between venting & BOOM but then it was the early eighties. OH & S? Bah! Humbug.
Would it work on LiPo you ask? Someone even more stupid than me can try it and write their own tale of disaster.
Seriously though people's, DO NOT TRY IT!!!! PLEASE!!!! You could end up writing your report in Braille with the stumps of your missing fingers.
Treat LiPo with care and enjoy Shooting.

AussieRider
 
cryzymotor said:
i think the real reason what caused the fire is the balance charger!!!

i never use balancer on BMS or charger, i told each of our cusomers, but but but i take notice of many many guys use li battery and lipo battery without BMS and use balancer for charging.

why cells will lose balance after some cycls, it is short circuit inside cell, we name that is is tiny short circuit. It is a certain physical property of each cell. There is no two same cells at all. We just choose or select some most simillar cells to build pack, after some times of charge and discharge, it aggravate the tiny short circuit, so we can see different voltage from cells, if we charge without balance the weak cell will be different with others more and more. and we should change the whole pack when we cant accept the shorter ridding range. It is this process to find which is the bad cell. It tell us do not use again and it dangerous.
But you charge with balancer inside BMS or charger, you will make different cells looks same, you will not know who is the bad one, so you charge and discharge again and again. The tiny short circuit becomes real short circuit inside cells, so it caused fire.

So do not balance cells again, guys!

The tiny circuit comes from tiny hole of plastic saperater and small thorn on the edge of anode and cathode once cutting.
Click to expand...

I agree that something has been lost in the translation of these insightful comments, and while I don't agree with the conclusion, there are important points worth understanding here.

One point is that using a balancing charger can obscure the degradation of the cells, since it forces them back into balance. This may be true if balance charging is used without a measurement of balance prior to charging, and if the balancing charger gives no data about the amount of balancing the pack required for each cell group. "Blind balancing", or balancing without data readout removes information (and most BMS's do this).

It is important to understand the condition of the cells, and never ignore the reality. Using a bulk charger and checking the cell balance manually shows the true tendency of the pack to the operator.

Even better is the balancing charger that charges the cell groups independently and shows the actual charge energy (amp hours) put to each group. This gives a numerical capacity indication of the balance situation which is especially important for chemistries like LiFePO4 that don't show capacity by voltage.

The other important point is that we need to react to changes in the pack condition. If the pack is doing anything unusual or different from previous behavior, we need to stop charging it, re-examine the reality and adjust appropriately. It may be time to retire or repair the pack. Continuing to charge it is inviting disaster.
 
I think that the issue cryzymotor is encountering with cells that don't stay in balance is caused by a couple of things.

First, the cells being used probably don't have very good QC, so they don't match each other very well even within the same batch, because the defective ones weren't weeded out at the cell manufacturer.

Second, the cells are probably being used beyond their actual capabilities (regardless of what the vendor *says* they are capable of, which is often not realistic, and probably doesn't reflect what the manufacturer actually rates them at).


When quality cells are used, that have been sorted well by the manufacturer, with defective ones removed from the supply chain, and they are used within the actual capabilities of the cell (not the extremes they might be able to do momentarily, but what they can realistically sustain without changing the characteristics of the cell, heating them up, etc), then during their expected lifetime they may not *need* any balancing.

As one example, I am running EIG NMC 20Ah cells, rated at 5C, and peak usage is around that, while typical usage is much lower (probably around 1C or less). There are balance wires on the pack but not attached to anything; no BMS, just occasional monitoring for testing. They stay balanced, even after years of use this way, using only bulk charging.

The only cells I've had any issues with were a single one that began to fail with higher internal resistance after several years, so it sagged more at higher currents, and three cells from a separate lighting pack that was accidentally run down to 0v once, but which still worked at lower currents; it's even been run down very low once after taht and only one of those cells died (puffed up) because it actually reversed voltage a bit. The other two cells still work at their reduced current rating, and are still in use now (with the original high-Ri cell in the same pack, also working at that reduced rating).

THey also do not heat up on their own, from use, in any of the testing I've done, because they are actually capable of more current delivery than the manufacturer rates them for, unlike many of the "generic" cells of various types which are rated higher than they can really deliver just for marketing reasons, as those manufacturers probably have no reputation to protect, I'd guess, and no warranties to worry about honoring, unlike EIG (and others that realistically spec their cells).


As an example of improper specifications, I've got a pack of 13s4p 18650 cells, which while probably genuine, are spec'd by the pack vendor for much higher currents than they can realistically sustain in that pack configuration (nowhere to shed their heat, for starters), and since the BMS allows this current, they'll get out of balance when used at the higher rates pretty easily, and the BMS will detect LVC on a cell and shut off the pack, even though it actually has plenty of capacity left if it were used at the lower rates the cells are realistically capable of, instead. The cells also wouldn't get hot if they were rated realistically.

Then there's various "who knows" stuff like the RC LiPo packs I've got, where even when new they didn't stay balanced, even when used at much lower rates than the pack vendors spec them for (and manufacturer specs are unknown, as the actual cell manufacturers are not known), and various cells could die (puff up) even just sitting there at median charge levels, while not in use.


So there are a number of factors in play
 
Oh wow,... this made my stomach churn bad and I'm glad it wasn't worse, as it easily could have been tragic. I shudder at such a loss of my similar cruiser. And thanks for posting what many may have been embarrassed of for whatever reason,... fact is, ALL batteries are potentially dangerous, and more should be aware that it's far too easy to become lax in our use of them. Regardless of the incident rate,... handle enough of them, and the incident WILL arise!!! And batteries in many forms are part of everyone's life.

Believe it or not,... I can recall the increasing popularity of the first newly introduced 9V "transistor" batteries in the late '50s early 60's!!! Something you jus didn't throw loose in the top drawer or drop into your change pocket (yes, we commonly carried coins in our pockets then!). Since then my, my young early intrigue and interests grew, and have kept me well aware of various new and evolving battery technologies in a great many fields of use. And I HAVE NEVER lost the concern of their inherent potential dangers, and try hard to make others aware as well!!! Too many assume batteries to be safe,... or safer than those of the past. And others get lax in their manner, while knowing quite well the risks involved. But each new development and application brings new hazards as well,... jus as those early 9V's did. AND,... I am not without an experience in battery meltdowns, violent explosions, fires, and other serious damage. No loss of life, nor serious or serious injury, thankfully,... and property damage has also been minimal. Due in part to safety and awareness.

Whether a "note pad" or flashlight, cell phone, hover-board, bicycle, automobile, portable speakers, WHATEVER,... make sure others are aware of the battery technology used and the proper use and handling of such. YOU jus may help others prevent a serious injury or tragedy.

and again,.. thanks.
And my bet, is that your next build will be jus a bit different,... having a personal experience and knowledge that others may lack.
 
Thanks people's for the support. I & hopefully other will gain.
I'll doc the rebuild in a new thread. This time with LiIon & a BMS with other changes as well.
Eden3 will return!

AussieRider
 
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