huge lipo fire , not cool

[Jeremy Harris]

still no info to use to analyze how the fire started. at least with the fire chroot reported we had some closure and understanding that it was a short.

since this is a metal box, it has to be analyzed to see if there is somewhere inside that indicates that the cells might have shorted out to the box initially to provoke the thermal runaway if that is what it is. if there was foam inside the box, it might have ignited itself initially too.

I agree, but looking at what we can see I'm not sure there's going to be much left in the way of clues, even with some better internal photos of the battery box. My money would be on a short, but that's based very much on the patterns of mechanical damage I've seen, and TBH that's only been a very small sample.

There have been a fair few pack builds pictured here on ES over the years that have worried me, but I've usually been reluctant to wade in and be overly critical, as often the builder has put a lot of work into them. Perhaps we should be more critical of what we see as potentially bad practice. TBH, I just don't know whether the potential benefit from pointing out serious flaws is worth the disruption it might cause to an otherwise peaceful thread.

 

[etriker]

still no info to use to analyze how the fire started. at least with the fire chroot reported we had some closure and understanding that it was a short.

since this is a metal box, it has to be analyzed to see if there is somewhere inside that indicates that the cells might have shorted out to the box initially to provoke the thermal runaway if that is what it is. if there was foam inside the box, it might have ignited itself initially too.

I agree, but looking at what we can see I'm not sure there's going to be much left in the way of clues, even with some better internal photos of the battery box. My money would be on a short, but that's based very much on the patterns of mechanical damage I've seen, and TBH that's only been a very small sample.

There have been a fair few pack builds pictured here on ES over the years that have worried me, but I've usually been reluctant to wade in and be overly critical, as often the builder has put a lot of work into them. Perhaps we should be more critical of what we see as potentially bad practice. TBH, I just don't know whether the potential benefit from pointing out serious flaws is worth the disruption it might cause to an otherwise peaceful thread.

For sure ! We let hk off way too easy on their quality control. We should reject sellers that treat us like they do and sell so many bad packs and for sure not suggest to others online to try them !

We really could do our ebike thing without them that is for sure !

Say no to hk lipo !

 

[ZOMGVTEK]

Most of the smoke was probably from the Neoprene mat, that stuff smokes really bad.

Before plugging in a bulk charger, it's really a good idea to check cell balance. The vast majority of LiPo fires happen as a result of improper bulk charging. I'm not saying thats definitely at fault here, but it sure is suspicious.

Really, any considerable amount of LiPo should be used like it can start on fire at any point. Charge and store in a garage, shed, outside, or somewhere where fire and smoke isn't that bad.

 

[migueralliart]

From the horror stories ive seen in the forums i do agree that lipo is scary. You should take the neccesary precautions these are my tips

1- All lipo enclosures in my bikes are not permanent. I take my lipo off the bike within 2 minutes.
2- This allows you to see wether there is a puffer after every ride.
3- I check all cells with a cell log before riding ALWAYS
4 - I never discharge more than the C rate of the battery and i mean for 20C stuff i dont even go past 5C
5- I stick to the rules of never below 3.6 never more than 4.2
6- This is the most important thing. I chrge and store my lipo in one of these and inside my garage

Bought it used on craigslist for 40$ and this thing WIll contain a fire. I drilled some holes at the front that points to empty space. These will be more than enough to vent the smoke. The top is heavy so i dont lock it.

 

[Jeremy Harris]

From the horror stories ive seen in the forums i do agree that lipo is scary. You should take the neccesary precautions these are my tips

1- All lipo enclosures in my bikes are not permanent. I take my lipo off the bike within 2 minutes.
2- This allows you to see wether there is a puffer after every ride.
3- I check all cells with a cell log before riding ALWAYS
4 - I never discharge more than the C rate of the battery and i mean for 20C stuff i dont even go past 5C
5- I stick to the rules of never below 3.6 never more than 4.2
6- This is the most important thing. I chrge and store my lipo in one of these

Bought it used on craigslist for 40$ and this thin WIll contain a fire. I drilled some holes at the front that points to empty space. These will be more than enough to vent the smoke. The top is heavy so i dont lock it.

Nice box, and great tips, pretty much what I do now after my NiMH battery pack fire scare a few years ago, except I bought a small metal tool shed and fitted it on a concrete base outside.

FWIW, I've only ever seen puffed cells from two causes:

The first is duff cells delivered from the supplier. HK are a bit notorious in my personal view for sending out packs with duff cells, I reckon that around 5% of the packs I've received have had duff cells, all have been Turnigy branded. None of the Zippy packs I've had have had any duff cells, but I've probably only had around 20 Zippy packs, versus maybe 50 or 60 Turnigy packs.

The second cause has been operator error. I once allowed a pack to completely discharge (I left the bike turned on for a few days in error) and compounded the error by trying to retrieve the pack with a gentle charge. I had a few puffers fairly quickly, and ended up leaving the pack outside on a bit of concrete for several days, then I discharged it by connecting a big resistor across it, got the voltage down to near zero and binned all the cells (after cutting all the leads off).

I've not (yet) had a lithium battery fire, but then I'm more than a bit cautious, both in the way I put packs together now and in the way I charge and monitor them. Maybe it takes a fire to ram home the message that these things, irrespective of manufacturer or cell chemistry, have the potential to cause serious damage if not treated with care and respect.

 

[etriker]

There is other places to get rc lipo.

http://epbuddy.com/index.php?main_page=index&cPath=22_23

Alot of the rc kids are bragging these up.

 

[hydro-one]

"Most of the smoke was probably from the Neoprene mat, that stuff smokes really bad."

i would have to disagree, the smoke was from the batterys, it was INTENSE SMOKE. I was lucky to witness this, now i see why people die from smoke, not fire.

My guess is A) failed bulk charger (overvoltage). b) bad cell discharged pack over the week. puffed and overvolted during charge this bad cell was likely caused by denting, chafing or whatnot. I dont think it was a short because the pack was fine and wasnt moved at all, just plugged in to charge. I will be looking at the case to see if there is any sign of arcing anywhere, and i will be checking the charger for overvoltage. Other than that i dont think we will know what actually happened.

I will find out about those points as soon as i can. thanks for the comments!!


ps there is nothing wrong with HK lipo!! ive had 500 cells without a dud on arrival. mabye one dud after several cycles.
that epbuddy lipo is probably hk lipo rebranded

 

[kfong]

There is copious amout of white and black smoke from lipos, you get streams of black soot everywhere. Until you seen or had a lipo fire, you really can't imagine the danger it imposes. They are nearly impossible to put out as well. Until the lithium chemistry burns off, you pretty much have to find a way to contain it until it does. These large 10 or more amp hour packs will bring fear when they go off. That's just a huge amount of energy to be released at an uncontrolled rate.

 

[bigmoose]

...There have been a fair few pack builds pictured here on ES over the years that have worried me, but I've usually been reluctant to wade in and be overly critical, as often the builder has put a lot of work into them. Perhaps we should be more critical of what we see as potentially bad practice. TBH, I just don't know whether the potential benefit from pointing out serious flaws is worth the disruption it might cause to an otherwise peaceful thread.

For what it is worth, I think we should start being as critical as is constructive to help improve the safety of battery designs. I know a lot of us have spent many an hour in design reviews (quoted author included). At least in the reviews I participate in, the focus on "is it right and proper and meets requirements, or does the design need revisions."

Again IMHO we need to develop and disseminate "best practices" for these battery systems. The alternative of "random" fires is not an acceptable outcome. For example, the original design used neopreme rubber likely for insulation, abrasion and shock absorption. If neopreme is not the right choice, what is? We should evolve towards that "best design practice." The only way I know to do that is to assess current designs, and identify suspect weak points. As for folks with thin skin, I know I would rather have my designs openly criticized on this board than have to throw my wife out the bedroom window, follow her, and watch our home burn to the ground because of one of my "experiments." Also, random failures that cause a fire, or shorts that cause a fire, are still failures "that count" in my book and need corrective action in design, material choices, and in fabrication practices.

I said to my wife a week ago, that I wonder if large electric vehicles will prove to be viable or not. I described to her my thought that the battery is a cauldron of angry electrons just trying to get out. And if there is a pinpoint breakdown of a 0.003 in thick insulator (of which there is likely hundreds if not a thousand or two square feet of in a battery system) all those electrons catastrophically escape and call upon their neighbors to break jail also. I added that there would never be an electric car parked in our garage, and any charging would be fifty feet downwind of our house...

For info I am attaching the A123 battery design standards to OEM's. This report was publicly distributed as an appendix to this: REPORT OF INVESTIGATION:
HYBRIDS PLUS PLUG IN
HYBRID ELECTRIC VEHICLE
Prepared for:
National Rural Electric Cooperative Association, Inc.
And
U.S. Department of Energy, Idaho National Laboratory

It presents some design features that A123 feels are mandatory for successful use of their cells. Some directly carry over to LiPo.

These statements are particulary germane:

• Pack must have dual, redundant over voltage protection, with at least protection by hardware and one via software
• The voltage of every single series element must be measured and monitored
• in multi cell batteries, use cell balancing and/or individual cell voltage controls to equalize the state of charge of cells in series.

Bottom line: Bulk charging without individual cell monitoring is unsafe, period.

 

[Jeremy Harris]

ps there is nothing wrong with HK lipo!! ive had 500 cells without a dud on arrival. mabye one dud after several cycles.
that epbuddy lipo is probably hk lipo rebranded

Not sure if this is aimed at me, as I can't see any other criticism of HK in this thread, except for my observation about getting a few dud cells in Turnigy packs, something others have also noted in the past (see this thread for my experience and that of others: http://endless-sphere.com/forums/viewtopic.php?f=14&t=24179).

Having said that, there's no doubt at all that HK offer the best value choice, even allowing for the occasional duff cell. Having been told (in confidence) of the source of their cells, and knowing that these are pretty good (at least as good as those from the most expensive vendors) the only area of concern I have is over the assembly quality, which isn't that great in my view. Certainly the Zippy's seem to be better than the Turnigy's, but both are probably worth looking at carefully if you want the highest reliability.

It's very hard to beat HK cells in terms of the price/quality balance, especially when some of the very expensive brands actually use the same cells.

 

[wesnewell]

So the enclose was lined with neoprene like rubber mat. He said he checked the cells a week ago or so and they were perfect. as they always have been, packs never been balanced in prob 400 cycles or more. he said they were never more than .08v out. The pack was made with three pairs of 5a 5s turnigy 20c/ . permenently connected packs in parrelel, then strung in series for 15s 10ah pack

bulk charging with meanwell 7 amps. we have the charger and i will be checking the output voltage when i get there again. (first thing that might have happened). He carries the charger around in a backpack so it may have got damaged (and i had removed the zener z1 if anyone knows what im talkin about )


he claims the bike was not plugged in during sitting for a week. and had been used regularily until then. so imthinking its either a "charger" problem or a dented cell that went to 0 over that week.


DO NOT CHARGE IN HOUSE TRUST ME, the smoke and fire is INCREDIBLE, and this was only a small bike pack

Well, I think that says it all. 400bulk charges w/o balance. enclosed so you can't see them or check if they're getting hot/puffed, etc. The only other bad thing would be if the charger was set to something over 61.5V. This is why rc lipo gets a bad rap.

 

[Jeremy Harris]

Well, I think that says it all. 400bulk charges w/o balance. enclosed so you can't see them or check if they're getting hot/puffed, etc. The only other bad thing would be if the charger was set to something over 61.5V. This is why rc lipo gets a bad rap.

I'd missed that point about balancing. My experience is that going for more than about ten charge cycles without a balance charge creates a potentially serious problem.

I think the following might well sum up a possible failure cause:

1) Balance can only be determined at charge termination.
2) Measuring cell voltage at any other time does not give a reliable indication of state of charge.
3) It is highly probable that the true cell SOC was seriously out of whack, unless cell voltage was regularly checked at the point of charge termination whilst on charge.

The consequence of bulk charging a pack that is seriously out of balance, without providing some form of cell over-voltage charge termination, would be cell over-charge failure and fire.

I strongly suspect that the root cause may well be a failure to appreciate that cell voltage is not a reliable indicator of pack balance, except under two specific conditions; end of discharge, when all the cells reaches a pre-determined minimum voltage (usually around 3.4 to 3.6V) at end of charge or when all the cells reach a pre-determined charge cut off voltage (usually around 4.2V per cell) whilst still under charge.

Cell voltage measured at any other time is a poor indicator of pack balance, and may well give a false assurance that all is well.

 

[Alan B]

Hi Jeremy et al,

Out of my collection of Lipo, maybe 40 Turnigy and 15 Zippy I have experienced zero puffed Turnigy and one puffed Zippy from the factory. One Turnigy pack has wonky cell voltages, all the rest are normal for new batteries.

Interestingly enough after sitting a few weeks the puffed Zippy looks normal now, and the terminal voltage was always nominal. I have not cycled it yet, I expect it will not be normal.

I check the cell voltages at the end of bulk charging while the charger is still connected, and even after dual daily cycles for 1500 miles they are still well balanced, and after disconnecting the bulk charger the cell voltages continues to be a good indication of the balance they have. This testing represents over 100 cycles of use and 90% of that has been bulk charging. At the start I alternated bulk charging with balance charging, but have not balance charged since going to bulk charging on both ends of the commute and have not balance charged since making that procedural change months ago.

I started a project to make a bulk charger monitor and control that looks at each cell voltage during the charge cycle for safety. This may be an alternative to a full BMS or always balance charging - a system that recognizes overcharging of cells and stops the bulk charge and alerts the user. My design also checks against bulk charger overvoltage conditions as well, backing up the power supply regulators. Onboard a simple and reliable low voltage cutout system may be the appropriate tool to prevent overdischarge. Together these solutions provide a network of protection that may meet at least some of the underlying requirements for safety.

 

[etriker]

"Most of the smoke was probably from the Neoprene mat, that stuff smokes really bad."

i would have to disagree, the smoke was from the batterys, it was INTENSE SMOKE. I was lucky to witness this, now i see why people die from smoke, not fire.

My guess is A) failed bulk charger (overvoltage). b) bad cell discharged pack over the week. puffed and overvolted during charge this bad cell was likely caused by denting, chafing or whatnot. I dont think it was a short because the pack was fine and wasnt moved at all, just plugged in to charge. I will be looking at the case to see if there is any sign of arcing anywhere, and i will be checking the charger for overvoltage. Other than that i dont think we will know what actually happened.

I will find out about those points as soon as i can. thanks for the comments!!


ps there is nothing wrong with HK lipo!! ive had 500 cells without a dud on arrival. mabye one dud after several cycles.
that epbuddy lipo is probably hk lipo rebranded

If you think hk lipo is quality stuff then for sure you should not be messing with lipo at all.

Look what you have done playing with hk lipo ! ! !

And this forum is turning into the lipo fire forum !

How many this year so far ? ? ?

Reading about all these fires really bums me out !

You need to learn how to use a regular bicycle ! ! ! People like you give evs a bad name ! ! ! Not cool.

 

[Jeremy Harris]

Sounds like a good way to go, Alan. The high capacity, but low voltage, pack on my electric boat has a permanently wired voltage monitor, with a 4 pole switch to turn it on (it's an 80Ah, but only 4S, pack). This works very well, I can turn the cell voltage monitor on when charging and keep track of the voltages at charge termination.

One of my Turnigy packs gets out of balance by around 1 Ah after around a dozen bulk charges. I keep meaning to strip it and find out why, but TBH have been too lazy, as the bike gets used a lot and none of the cells has ever puffed. The cell voltages are always within around 40mV or so when I check them with a Cellog, it's only when I do a balance charge that one sub-pack takes a fair bit extra energy to charge. It's consistent, and something I've always put down to a variation in cell capacity from normal manufacturing tolerances. This pack is now a couple of years old, with a few hundred cycles, so maybe it's time to replace it.

 

[kfong]

Thanks Bigmoose for the post, I was surprised I was not able to cut and paste from the PDF. I wonder if it was A123's way of not being quoted due to liabilities. Anywho, I liked the mention in the specs of state of heath by monitorirng the history of a series cell at beginning and ending charge indicating the internal resistance changes over time. Something not provided by current RC chargers I'm aware of, just the overall internal resistance currently. I also noticed the A123 have a vent release area at the top and bottom end of the pack. I wonder were the saftey venting area if done with Lipos is normally directed, if at all? A useful best practice thread for lipo installers would be a start. Since this is a DIY group and many tend to do it their way. Directing them to a thread might be a good approach.

I for one prefer the packs to be housed in a fireproof container such as a metal or carbon fiber housing on the bike. This to me seems to be a good way to contain the fire and reduce collateral damage. Obviously it makes visual inspection difficult, but cell level monitoring and charging is implemented. Unfortunatly even I don't have my housings completed and this is going on 2 years now. Hopefully this winter I will make progress in this direction. I have found the hard shell provides good protection to the lipo cells during the many trail crashes I had over the 3 year span.

 

[hydro-one]

Etriker, , show me your perfect battery pack, at least i have 10 evs on the road, how many do you have. suck diesel fumes. i ride a pedal bike just fine and my ebike , and my peddle bike are alot cooler than yours.

charge outside and all is well. I have thousands of miles on my hk lipos . they have been a good value to me. and i dont even own a balance charger anymore, my packs are matched so well.

The pack was checked every few charges for balance, good point about SOC during checking for balance. The pack was never going out of balance, to me that means all is well. The enclosure wasnt full, and he looked at the cells fairly often to see puffing. plus a puffed cell would have shown an out of balance voltage i would expect. It is possible he had been missing one of the packs when checking or something like that, and one got damaged during a crash (many crashes, guy crashes alot)

charge outside always

 

[etriker]

Etriker, , show me your perfect battery pack, at least i have 10 evs on the road, how many do you have. suck diesel fumes. i ride a pedal bike just fine and my ebike , and my peddle bike are alot cooler than yours.

charge outside and all is well. I have thousands of miles on my hk lipos . they have been a good value to me. and i dont even own a balance charger anymore, my packs are matched so well.

The pack was checked every few charges for balance, good point about SOC during checking for balance. The pack was never going out of balance, to me that means all is well. The enclosure wasnt full, and he looked at the cells fairly often to see puffing. plus a puffed cell would have shown an out of balance voltage i would expect. It is possible he had been missing one of the packs when checking or something like that, and one got damaged during a crash (many crashes, guy crashes alot)

charge outside always

You just don't know how many people I have shown my bike to and had them look right back at me and say, yeah but the batteries will explode on that thing.

And now you have shown they are right ? ? ?

I think we should really try and not give the ev haters any more ammo. Like you just did with this thread ! ! !

You did it to save a few bucks, right ? And sold out evs.

 

[hydro-one]

i dont give a frock about ev haters. I only deal with ev lovers. if you hate ev's you are either really ignorant, stupid, or you had your house incinerated by one, in which case you already love them. :lol:

The kind of people i dont like are ones that try to smear products because of some hidden commercial interest. and then offer up the solution to the problem which is to buy thier products. ]

 

[kfong]

Mistakes happen even in large companies with stringent regulations. Accusations becuase someone rains on your lipo party is silly. I for one feel Hydro-one was very responsible. I wonder how many have had fires and have not talked about it. We might never find the root cause, but the fact remains. Lipo fires can happen and what you do to reduce such risk is really useful info to know and not assume that a fire will not happen to you.

 

[etriker]

i dont give a frock about ev haters. I only deal with ev lovers. if you hate ev's you are either really ignorant, stupid, or you had your house incinerated by one, in which case you already love them. :lol:

The kind of people i dont like are ones that try to smear products because of some hidden commercial interest. and then offer up the solution to the problem which is to buy thier products. ]

If you love evs then do what ever you can to not cause a new lipo fire thread on this forum.

So far you are a big ev fail ! ! !

 

[Jeremy Harris]

Take a tip from me, hydro-one, just stick etriker on ignore if he's posting here with his usual in-your-face aggression. I did this a couple of months ago, and can say it saves a lot of aggravation when you don't get to see his stuff, as the guy only seems to post in order to provoke an argument, rather than take part in any sort of civilised discussion.

 

[hydro-one]

yes i will try to not cause a fire , obviously.

Are you suggesting that i should not have posted this thread, because it will scare people away from evs? If it scares them from bulk charging in thier house, thats exactly what im trying to achive. I know there are alot of lipos around here, not all of them are that "good quality" epbuddy lipo that the rc guys are chirping about, and I want everyone to know, even if you are very careful with them they still can go boom.

as for mistakes i made in the design and dissemination of said lipo pack, yes im working on correcting that.

jeremy, yes but its an argument i can win lol

ps thanks for all the great posts guys, i really value all this discussion, bigmoose you are very right to be concerned about the future of large evs. Thats why i probabaly will never "go big".

 

[etriker]

I really don't care.

I care about all the other people that might find and read this thread and hopefully they will not buy hk lipo and start a hk lipo fire thread.

Just the words "bulk charging hk lipo on electric bikes" pisses me off ! ! !

I am really getting tired of the lipo fire threads !

 

[etriker]

yes i will try to not cause a fire , obviously.

Are you suggesting that i should not have posted this thread, because it will scare people away from evs? If it scares them from bulk charging in thier house, thats exactly what im trying to achive. I know there are alot of lipos around here, not all of them are that "good quality" epbuddy lipo that the rc guys are chirping about, and I want everyone to know, even if you are very careful with them they still can go boom.

as for mistakes i made in the design and dissemination of said lipo pack, yes im working on correcting that.

jeremy, yes but its an argument i can win

I will help you out.

Rule #1 of building a good battery pack. Use high quality cells. #1 rule.

HK lipo may well be the lowest quality li ion cells there are.

These may well be the best.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=36589