The Video I've been waiting for for years. I've always wanted a competent persons perspective on ebike fires with technical background. The only people that seem to speak on these are experts on extinguishing fires not on how they start.
I work for QBP and provide support for FAZUA. Watching this is so amazing because I've explained so many of these topics to consumers and dealers. Great job, NAILED IT!
One thing I've done with all of my home-made batteries is to wrap them in a layer of fiber-glass fire blanket under the PVC cover. Not only does this help reduce the chance of a fire spreading, but glass is an excellent electrical insulator, and it offers an abrasion layer to protect the batteries underneath in the event of a crash. I also use the JK-BMS. These are really nice as they have active balancing (meaning they can balance during both charge and discharge), have two temperature probes, a bluetooth GUI, and lots of programmable safety features, including over temp, under temp, short circuit, over current, over voltage, under voltage, etc.
This is all good, but nothing the bms does can make up for a situation with low quality cells that go into thermal runaway all on their own even when always kept with nominal operating conditions. So in addition to those precautions, you should still only use top tier cells, even if they cost a fair bit more per wh than generic ones.
@@GrinTechnologiesAbsolutely! I do bike touring, so last thing I want is to get stranded by a battery fire or failure. Also, in my experience top-tier batteries last longer, and so pay for themselves anyway.
Great talk Justin, I have followed you for years and am amazed at your great work. I remember when you had a contest to name the cycle analyst. I' ve had 2 fires, both my fault, no one hurt. Lipo - I hooked up a 3 series to a 4 series ? thinking I was hooking up my light. oops, then hooked negative to positive on a 4 series, in the dark again, , and I felt the heat, not a fire just a wire heated up melted the solder so that broke the connection. Now I use Li ion on my bikes, they work great. I add a lipo as a booster pack sometimes but I make sure I hook it up carefully in the light.
Lol, thank you for advice of this matter. But It is best to keep my preference of normability of my uses of all 4 of my ebikes of the extreme need of avoiding these scenes of ebike fires. I lived thru wildfires and even in my home and FIRES is a moment in life no one needs to witness of experiancing ( its total dredd ) and myself with ebike use, I rather ensure I have no need to mess with the ranges of specs. Im sure its useful to many but for me I just keep em simple. Ride safe and be safe and thanks for your experience of this matter.
Great video, seeing the stuff that OG ebikers had to deal with back in the day makes me thankful for how much easier it is now. It seems like I got interested in ebikes at the perfect time.
I think I'd add to your presentation the danger of leaving the battery exposed to sun on very hot days. That may cause a rise in internal temperature and subsequent explosion. Happens with GPS units stuck to the windshields of cars. That might've been the scenario in the case of the scooter by the subway station in your leading slide. Grin rocks, learning a lot from your videos.
The early days portion of this video is so fascinating to me. I got into this in 2016 and the not-so-distant past seems like such a mystery to me. Someone needs to write a book.
The ebike movement really started in earnest as a thing in the late 1990s. There was some stuff in the 1970's that never went anywhere, but by the 90's you had zap, Currie, aerovironment, heinzman, Ev warrior and a bunch of other brands setting the stage for what was to come.
@arobertson87 I got in in 2003 when the Voloci ebike from new Hampshire debut.. NIMH batteries were terrible, needed to be topped of just prior to leaving, and the sag in winter was tremendous. I hen went to NICads from Justin , heavy as heck, nd they would get super hot.
I only started in ebikes in 2014 so have the same feeling as you. I did used to race R/C cars during the Nicad & Nimh era so I know how big a step Li Ion & Lipo were :)
Great presentation! Thanks for taking the time to compile all these years of experience and distill it down to concise and coherent messages. The Grin mission in full effect and always a bit entertaining too!
i used to fly rc helicopters and air planes with this amazing older man i had met at the flying field. He was charging his batteries one night in his garage connected to his home and one of them failed causing a fire. He had his lawn mower in the same garage with a gas can which then exploded igniting his car and eventually the rest of his home. When he told me this one day i was super shocked it just seemed like something that doesnt really happen to people you know. After losing his home and it was a very nice home his wife was so angry she left him and filed for divorce. One week later the man had a heart attack and died. It was really super sad because he was the nicest guy i had ever met and so helpful at the flying field with his knowledge of batteries and charging. Goes to show it doesnt matter how much you know about batteries they are still unpredictable and could ignite at any time for no reason. Please charge your batteries outside away from your home because once these fires start they do not go out.
Wow - such a good presentation, particularly case histories! This brings to mind something paranoid that somebody said to me years ago: "Never charge an unknown/suspect Li-Ion battery anywhere that you wouldn't start a campfire"...
I ran a hobby lipo 14s8a pack without bms but was very careful when charging it. Eventually I got a Bluetooth bms and found out that 5 of 14 cells were dropping below 2v whenever standard throttle was used, and immediately recycled the pack. Thankful I never experienced a fire, always kept the battery in an ammo can just incase
Definitely a lot of close calls that happened in between all the various actual hobby LiPo battery fires. Glad you were taking precautions, and please keep spreading the message that every lithium ebike pack (and especially a hobby grade LiPo pack) needs a BMS!
Fantastic talk! I hope the regulations don't make ebikes even more unafordable. Wish there was a way for governments to just ban the sale of unapproved cells. I just finished building a custom full suspension commuter ebike and it was one of the most fun/rewarding projects I have ever done. Ripping over all the speedbumps here in Vancouver has never been more fun 🙃
Very good presentation. Ryobi has been using Chinese EVE 18650's for about 4 years. Power tool fires do happen, but yes they seem quite rare for how many power tools are out there and how much they get abused. Speculation is: the energy density of cells used in power tools is far lower, 1.5 or 2Ah, compared to 3-3.6Ah used in some ebikes. Lower energy density means less flames, gas, and heat are emitted (non-linear), less chance of thermal runaway. Add to that the cells have high discharge ratings, so should heat up less and hopefully designed to age better. A major concern with cheap Chinese packs is not the brand of cell used, but that they can be using recycled mixed cells that are poorly matched. You might have a pack with an old, lower capacity, high ESR cell right in the middle. That one is going to get hammered, and probably start heating up the most. For a BMS to handle that failure you'd have to have a probe on every cell which is not realistic.
Why is that not realistic? A thermal probe is less than a dollar. Also, the BMS should in most cases be able to identify the cell by voltage difference/current on the balancer.
@@llejk Have you ever constructed a pack before? Manually soldering and running probes is a huge pain in the ass and will drive up the cost. The BMS doesn't care about the voltage difference unless its exceeded the min or max voltage, at which point it shuts off. Its not going to know a cell is in a hotspot, and even if it does, you'll just get constant nuisance trips.
as an RC pilot I learned all about how to keep your stuff from exploding in flight or while charging.. the hard way. And I always just assumed that the same kind of mistakes (maybe even intentionals) were being made in ebike factories. And that's what this video pretty much says! You can get the entire battery and charging system for less than half the price if you take out all the designed-in safety features, and there are manufacturers out there serving that market.
Timely video, thanks. I am just a newbie in ebikes. My first effort is a rebuild/upgrade. The new battery is coming from a company that seems to have a good and long term rep; worst being that the battery is less powerful than described, the company seems responsive to these complaints. The final check in their favour was that this battery was designed to make the most out of my specific battery enclosure.
THANK YOU for this detailed, necessary presentation. It gives me peace of mind because my 2 wheel drive E-CELLS Super Monarch Crown uses 2 SAMSUNG batteries, 15 Ah and 20 Ah. (Downtube and under rear rack). I'm not surprised that Dave Clevelend, the designer of E-CELLS e-mountain bikes, uses SAMSUNG because all of his components are high quality. -> Actually lithium iron phosphate batteries weigh only about 20% more than Li-ion batteries of equal power but have TRIPLE the charge/discharge life to any chosen %.of maximum charge relative to its new state of 100%.
Excellent video, i have holding off on the ebike because of the fire risk. I found it difficult to understand this issues and why these were happening and this is exactly the kind of information i needed.
You fail to mention UA-cam video's being posted of amateurs building DIY lithium batteries packs also upgrading chargers so they charge faster. Not only are they putting themselves at risk also other from lithium fires. The whole industry in sales and repairs needs regulation, so standards can be increased.
Agreed that the proliferation of YT vids encouraging DIY battery assembly encourages a lot of people to do things that they shouldn't. Part of the reason is that there is zero ebike service and repair industry and the ebike manufacturers do everything to discourage a healthy aftermarket,leaving no option than DIY repair. Re faster charging, There is generally no problem charging lithium cells up to 0.5C charge rates, while most stock chargers are only like 0.2C or less. So upgrading to a faster charger is quite a reasonable thing to do as long as the actual connector type on the port supports it. This is not a battery fire risk.
My bike is extraordinarily unlikely to combust, because I’m the battery and the motor. By the time I’m old enough to need an e-bike I hope they’ll have the battery tech figured out. But the crappy fuses and bad construction are going to be with us as long as there’s a profit incentive
I’ve purchased ebike batteries from china, and i was dismayed at the poor construction build…balance wires crossing over the top of the cells, without adequate insulation, and poor support for the cells, allowing them to move, and chaffe inside the case…a timebomb ready to go off.
Great talk. Lots to consider in building my next diy bike. Current bike uses a pack from Epower and i shopped on price not really knowing all the details.
Lets say you keep your battery at around 20% charge when you're not intending on using it. Does it stand to reason that further decreases the chance of a cell suddenly catching fire? (would a battery at 80% charge be more likely to catch fire then a 20% of the same bat?) Another question: what are the chances Lithium ion battery's from hand held gaming consoles that haven't been charged up in 10 years to make a fire ? (asking since I have an old psp, and a nintendo DS, and a couple of old samsung batteries around) - I never realized being undercharged/empty could be a hazard too - should I just get rid of these?
What I would suggest is to charge your Li battery inside a closed self cleaning oven. My thinking being that these ovens can handle 600⁰ F temps or higher. Also charge the battery when your are awake and in your living place. This being advice for most appartment residences. Another method is charging the battery in metal trash can in a safe area. Feed back me if you have any ideas on what i just suggested.
I've been charging my ebike battery inside my oven for quite a while now. I also babysit while it's charging, and make sure it's unplugged as soon as it's done.
Thank you for this great presentation. It is shocking how hard this information presented here is to find. I dabble with DIY ebikes, I use reclaimed A123 batteries. They seem very stable. I take a hit in capacity and weight, but have huge gain in amperage both charging (4C) and discharge, and safety
The original A123 cells were really one of a kind, most of the inexpensive lifepo4 available now doesn't come close to matching the ruggedness and C rate capabilities of those old cells. So yeah, if you don't mind a hit on weight those are some great building blocks.
About overdischarging: This will probably not immediately damage a cell. If you leave it around for days or weeks, then it will damage the cell by chemical processes. If you recharge it immediately, then probably not much will happen. For security I store my battery in a large ammo box, together with some liters of water in plastic bottles. You need about 600 Wh to vaporize 1l of water. And about 90 Wh is needed to heat 1l from 20°C to 100°C. So I hope, this will stop a fire as early as possible.
I'm glad to see Grin having this conversation and taking battery safety seriously. I was working in Ebike product development for a manufacturer in Seattle, and was in fact a Grin customer. When I took on that project let's just say things weren't well understood, and in fact dangerous. I pressed for standardization and increased safety measures, ultimately coming to the conclusion that in the future these batteries, BMS, and chargers should be certified by the U.L. I would go further to say that the BMS is not capable of monitoring individual cells, instead it tracks a parallel bank of cells. Should one of these cells be faulty it can lead to over charging of other cells on that circuit.
Realistically its people buying cheap, or scam batteries, which then have very cheap BMS's that in turn cause a disabalance and then have the cells explode. People should stop wanting to buy 48v 20 ah batteries for 150 euros or dollars, its not realistic, and will get you burned.
Indeed, BMS just tracks parallel cell groups. In our experience, the individual faults of a cell in that group are either: 1) Disconnection from the group, (eg from a bad tab weld or an internal disconnect within the cell can). This results in that group having less capacity than the other parallel groups, and during charging it will reach full charge first. The BMS circuit should stop the charging once that cell group voltage is high, but if the BMS circuit fails at its task, or someone charges from the discharge port where there is no overcharge protection, then it result in overcharging as you say. 2) Internal soft short. In this case, one of the cells has an anomalously high self discharge rate and drains the parallel cell group faster than the BMS is ever able to balance it, eventually resulting in this group all getting discharged to 0V. The BMS circuit in this scenario should prevent both the charging and discharging of the pack. If it is charged in a way that bypasses the BMS charge cutoff mosfets, then all the _other_ cell groups in the pack get slightly overcharged.
@@GrinTechnologies In the event a faulty cell or connection should become faulty there is not usually an indication to the end user that such an issue exists, they simply wait for the LED on the charger to turn green, perhaps notice a subtle reduction in range if they frequently check. But few do. It really needs to be black and white for the end user. I'm sure you're focused on the same things.
Those pack are just great. All the instances here were from like 2014 or earlier, when both the cells and the overall assembly techniques were not at the same level
Awesome talk Justin! I was expecting to hear about battery storage (ie metal containers to prevent fire spread) used during charging. Great info about buying named brands and avoiding issues in the first place. Thank you!
If you aren't confident in the source of your cells then charging in a place where fire would be contained and can't propagate is certainly a good idea. But with good cells and a good bms, this kind of step is hardly necessary. We're not a fan of either bosch or Shimano propriety systems, but they have 10's of millions of ebikes out there with no one charging in a metal box and no one having fire issues either.
That was a really good slow build to a conclusion I thoroughly agree with. Standards don't necessarily make things safer through Engineering but through keeping out small guys. While this may be good if there's no innovations yet to be found it kinda kills off innovation which is frustrating for us backyard tinkerers.
As long as the UL2271 will NOT adress the cell spacing or Thermal Energy Absorbing Material between cells the UL will mis the goal ! Thermal runaway is one thing but thermal propagation is also VERY IMPORTANT. I have this document and revised it completly and from now it will help but not help the best as it could.
Well do and thank you. What is the UL, NFPA, FM and NEC standards regarding Lithium batteries including charging and storage and do these need to be addressed
Failure sources: - R/C flight hobbyist lithium-polymer batteries out-performing gas for power, range - 7:44 [is this due to scale inefficiencies of small gas engines? could a micro diesel power plant driving main horizontal thrust prop + electric vertical-take-off and control rotors work efficiently? How does electric vs. gas scale to human flight machines?] - Water facilitating galvanic current between cells and through casing to cells - Tab weld failure 16:30 - Tab material overloaded 16:55 - Mechanical impact 17:20 - BMS circuit failure - electrical overheating within internal pack circuitry burns polymer casing materials = electrical not lithium fire Failre Consequences - eBike business fires 19:50 - eBike business fires (home auxiliary facilities) 20:50 Small Cell Packs > Large Cell Packs - easier to locate issues within pack - industry convergence on 1850 type cells pushed development and standardization for small cells - allows more granularity for overall form factor of battery pack - 1850's vary in quality / China market includes lots of counterfeit BMS DETAILS What is the problem the BMS solves? ~ 24:30 - eBike end user doesn't attend to any of it -- the management is baked into the battery -- down to each cell in the pack. - BMS and maintaining 1850 standardized-cell specks 25:10 - What are consequences of out-of-spec charge/discharge for battery cells ('cracking' the case/BMS to recycle individual cells) 29:00 -- testing indicates it's nearly impossible to use consumer methods result in fire. End users can't do it. Fires are defects (or extreme mechanical) CONCLUSIONS - 31:05 -- safety demands decades-long R&D / product evolution of a large company's small cells (1850's), ensuring safety even in extreme abuse cases, down to the cell level (BMS, internal circuitry all prone to various failure modes). - 32:50 -- cordless power tools do have fires, but rate is minimal -- and it's likely because typical consumer buys name-brand tools with proven cells in their battery packs - 31:50 -- we need incident reports to indicate the brand cell involved in fires UL listing now required in NYC- 34:15 - Doesn't require proven battery cells -- Samsung, Panasonic, LG - Forces massive cost to sell an eBike battery or whole eBike setup - $40,000 per battery design to go through UL testing How To Extinguish - 39:09 Run-away heating drives lithium battery fire - Water = yes: quench the heat - CO2 extinguisher (not common household) extinguishes flame and cools - Chemical ABC extinguishers (typical household) make a mess and won't address internal heating that restarts the fire
Bms circuits have sense leads to all of the cell connection points, which means a failure that shorts those leads together can result in very high discharge currents in pretty thin gauge wires
my ebike battery always stopped working quickly and was charged quickly. it was an 8s 24V lifepo4 the BMS only looked at the first 3 cell groups, which was fortunate because the 2nd and 3rd series were defective due to corrosion 1V and 2V and the rest 3.7V
Thank you. Before watching this video, I had decided I want an ebike. Halfway through this video, I had changed my mind, deciding maybe I did not want an ebike. By the end of this video, I've decided, yes, I do want an ebike, BUT I now intend to have a CO2 fire extinguisher as well... and will never, ever, ever walk away from a charging battery. Heck, after this, I won't even charge my flip phone without supervision. It seems to me, this battery industry is in serious need of some worthwhile regulations, controls, or checks & balances. Safety first. A cheap battery is nothing next to the price of a home... or skin grafts... or a funeral. The bucks saved are not worth it. Peace of mind is an amenity that will sell. Somebody needs to step up and make that amenity happen, even if it means complete manufacture of the battery, start to finish - no outsourcing or importing anything beyond raw ingredients. Clearly, there's a market for that. Until then, seems like getting an ebike will be like playing Russian roulette. Maybe, they should all be charged in the middle of the yard, with a 100-ft extension cord, and housed in an outside shed (or kiln), custom built with climate controls. My, my, it just gets more and more expensive to have a battery with cheap components. Where is supply and demand in this? I want better. I'm sure most others do as well. If not addressed, people will stop getting electric bikes, because, if they haven't done so already, insurers will bilk or cancel ebike owners' homeowner's policies due to the risks. That, or they'll just start denying claims for losses of and to homes, other people's property, and actual people. Ouch! And renters...? Sounds like grounds for eviction to me, like boiling gasoline on the stove or having a meth lab on premises. So, yeah, I would pay for safety, regulation, controls, and a spot-on final product. Until we have it, I will equate the ebike to a Ford Pinto. What a shame.
You should have no real fears on concerns about having an ebike that uses quality grade cells on the pack contruction. They are insanely reliable and robust these days. The Sanyo / Panasonic GA cell should be crowned as a superhero in that regards. Your life will be massively improved by having an ebike, and your risk of fire from conventional sources (toasters, heaters, bad household worrying etc) will be much hight than from the pack. The risk is buying a cheap generic ebike which cells of unknown provenance. Then you do introduce quite an unknown element of risk
@@GrinTechnologies Thank you for the response. That makes me feel a bit better about getting one. I'm looking at the Lectric ebikes - they make one that folds for tiny living spaces. I now like the idea of that battery being inside the bike frame. People tell me they are good ebikes. But... think I'll still get one of those extinguishers to have on hand, just in case. It's bound to be cheaper than my deductible - LOL.
There are also lithium battery charging safe boxes that you can buy. Though there's also a possibility they can spontaneously combust, so you'd have to take them off and put it in the box whenever you are storing it at home, if you want to be completely safe.
How about Sodium-Ion batteries for eBikes? I think I would be happy with a reduced range because I only do short journeys at a time (between 1 and 4 miles). I'm sure in densely populated areas many people would be happy with a shorter range but with the benefits of Sodium ion tech.
With good investigation technique, The real cause of these fires should be VERY easy to track down with basic statistical analysis. It may not even be the batteries themselves but the controllers they're connected to. We need to focus on BMS technology. I have a pack from a hover board that I couldn't destroy if I wanted to because it has overcurrent /short circuit and over/under-voltage protection 3.2 to 4.15v. I suspect most consumer packs are like this. This could also be caused by bad chip programming within the BMS. The charger used shouldn't matter if the BMS is well designed. I've been a lithium battery collector for a while and haven't had a single fire or even an overheating condition. I always charge my cells to the right voltage using the factory charger and quality hobby chargers with lithium battery settings. The fires I hear most about are from racing drones with their unprotected pouch cells being physically damaged over and over. None of my drone packs ever gave me issues aside from the occasional cell going bad. If not for the internet or media, I would have never known of lithium battery fires. I think it's far less common than the media would have you believe. The media loves sensationalism and lithium fires make for juicy content. Don't buy cheap cells and only trust Sanyo, Panasonic, Sony, Samsung or LG cells. Most other brands are hot garbage from China (a country who both relies on us economically and hates us politically). I think Samsung and Panasonic are the best but that's a battle I won't fight.
Thanks for your perspective. It's unfortunately that the fires themselves almost always destroy the all evidence as to what sequence of things caused it. But all the circumstantial evidence with ebike battery fires (hobby RC is a totally different scenario) suggests that most of the fires are not the result of faulty chargers or faulty BMS circuits, or customer misuse, but faulty cells. It doesn't matter how good your BMS circuit is at preventing overcharging or overdischarging, if a cell develops an internal short circuit and goes into thermal runaway because of poor process control and QC by the cell manufacturer, then your hoverboard pack can be just like the 100's of others that burst into flames during normal use. Agreed 100% on your final statement too!
Camera Overheating Use External Battery, cooler like small fan or cooling pad (no noise), lower ISO and most common is mismatched SD card class rating for video being recorded.
The sad thing is that because of these early hazardous batteries a lot of public transit will not allow any electric mobility devices on their services meaning the promise of connected transit needs to wait until they can be sure that all of the old cells are out of circulation, which could take years.
using a proven battery is a good idea. I’ve built battery packs from scratch, with success, however, I have found after years of testing, that tool batteries, such as dewalt, can be used with great success. Custom building a rack, to hold these batteries securely, and to multiply voltage to the desired value….and likewise, parallel to increase capacity. The only downside, is that batteries must be removed to be charged individually on its own charger. But, for safety, and long lasting durability, this does work well. Still using an ebike after 10 years with this setup, a hubmotor and controller from Justin’s ebike store👍, and 9 dewalt 20 volt batteries in a 3s and 3p configuration, that clip into a rack that fit securely inside the bike’s triangle frame, resulting in a 60 volt 12 amp/hr pack. I charge all the batteries full before inserting them into the rack, so there is no voltage difference between batteries. Reliable, predictable performance. 3 chargers can get all nine batteries charged and ready to go again in 3 hours👍. Thanks for the video! cheers from northern BC🇨🇦
Great video. Do the batteries you make have a fuse in line with the charging circuit? If not why? Do your batteries have the ability to monitor via bluetooth/app? Could not find this info on your website.
Some BMS (so-called Smart BMS) will monitor the parallel cell groups in the battery via blutooth. You can detect odd behaviours very easily with these, without having to rip apart the battery.
No denying the early Chinese Li-Ion and Li-Po battery tech wasn't exactly safe to use. I had some bad experiences when I tried to adopt them for R/C cars. I waited a good long while for the Tech to progress before I could start trusting them again. Also educating myself on proper care and charging for Li-Po/Li-Ion went a long way. Nothing like Ni-MH that I was familiar with.
Hi, Thank you for this video. I just received an old electric scooter and an ebike, im looking into upgrading their motors, battery setup. Glad i came across your video. Every so often you'll see on the news about house fires starting from overloading or charging batteries killing family members. This might be a dumb question, but do you recommend any companies where they do have a reliable diy kits for my projects? Again, thank you for this informative video. Probably saved my home from Any future fires caused by buying batteries or counterfeit.
Molicell is an interesting player. At one point 20 years ago they were among the early leaders and did cell production near here in Vancouver. I know early on they had fire incidents, we don't hear too much about them now
They are for R&D, but all manufacturing went overseas a long time ago, partly to shield from liability after they had fire issues (I had a friend who worked in the plant back in the early 2000's)
Specs are labeled for a reason, to prevent one of the components from overheating. Its why I NEVER use a battery of placing on a controller a range of 36 to 48 ( 52v ok for 4b benchmark ) of my batterie at 60v or higher. As long as I KEEP ALL THE SPECS IN RANGE AN USING PROPER Volt's AND WATTS ,I ll be well safer than sorry as FIRES are NO JOKE ( wildfire survivor ) and NEVER RISK using components away from the spec range, its there for this reason alone.. Also CUTTING WIRES TO INCREASE SPEEDS is a SERIOUS NO NO, time will catch up with doing this for sure.
The nominal published ebike component specs in many cases are meaningless, especially with regards to voltage and power ratings. With regards to cell specs, even if you use the cell entirely within manufacturers guidelines, the risk of a spontaneous thermal runaway is always present with generic grade cells. Your recommendations here seem relevant but largely miss the point. Most ebike battery fires have nothing to do with using components outside of their spec.
Thanks for the video. I have a 10 year old Lifep04 battery. How old is too old? Should I recycle it before I have any issues? What about Lithium ion 18650s? Is Grin going to produce their own batteries again? I liked the idea of every cell being monitored vs a string of cells.
Note that there are no problems with Lithium Iron Phosphate chemistry batteries. Industry just doesn't use them because they are slightly larger batteries than lithium ion batteries 😢
We dealt with 5 different manufacturers of lifepo4 ebike battery packs back in the day (both in cylindrical and prismatic cells), and none of them had even close to the reliability or the cycle and calendar life we see with the current leading brands of li-ion. Would love to know how modern lifepo4 has kept up, but since A123 left the scene many years ago there doesn't seem to be any respectable manufacture of LFP cells in the caliber of Samsung, Panasonic etc Even at double the weight it still could have widespread use as an intrinsically safer alternative for sure.
@@GrinTechnologies they have gotten much better than the early days. But the main problem is with how they are being charged still. I built my own LiFePo4 pack three years ago for my ebike, and the capacity got better and has not demished at all. But the key to my success has to do with unidirectional impulse charging that uses little current so does not heat up the batteries at all, even though it is delivering 1 amp impulses at Mhz speeds. Its a method that can't be used on lithium ion because they are real finiky and likely explode. This method was invented by John Bedini for lead acid batteries, and the LiFePo4 ended up working great with it too. Unfortunately he passed, and not many of the battery chargers out there, and few of us are out here that understand it enough to build our own.
I've got a lifepo4 from 2019 that I am only now retiring because the voltage is dropping. There's no reason for most people to use a li ion battery on a bike in 2024. Lifepo4 is plenty powerful and lightweight. The tradeoff is completely foolish now.
Damn. As a ebike diy guy i am quite disappointed. I thought it was because of the charge/discharge protocol. But now he says its about the bad cookie in the lot that does a thermal runaway due to dendrite formation. This is so sad because i have so many batteries laying around. I realise my practise is unsafe. However i did manage to get thermal runaway by charging a overdischarged 18650. The reason this battery was flat probably is the dendrites: self discharge during charging= thermal runaway.
That's certainly what all the evidence points too. We're normally huge DIY advocates for those with the skills, but with lithium batteries the unknown risks inside the cells are just too great. If you are doing it, you should really only work with new top brand cells. Save the recycling / repurposing of used lithium cells to stationary power applications or other scenarios that can be properly quarantined.
Luckily battery quality and chemistry has greatly improved over the years, now we have chemistries like lfp, lto and sodium ion is starting to come to market that are much more stable You can find demonstrations on youtube of destructive testing of lto cells that are incredibly boring, but lfp is the best balance between volatility capacity and ampacity in most cases
There's an eBike battery sold in the UK that has been banned. Called UPP, it's in a triangular shaped pack that straps to the bike frame. It was sold on Amazon, eBay etc in the UK. Trouble is the authorities (OPSS) banned them on the big online platforms but the product was still sold from smaller online retailers. Just did a search and it's still being sold. They have caused a number of fires, and have a poor BMS (maybe non existent).
UPP is just one of a hundreds of overseas battery builders that sell direct to consumer in the west but don't have any accountability or liability in the same way that a western based company does when things go wrong. As long as that's allowed to be the case, then the competitive landscape is stacked heavily against the emergence of a reputable aftermarket battery business where only responsible players are involved, ie those who take responsibility and liability for what they sell. Unfortunately this also incentivizes companies that make products which use lithium batteries to create all kinds of proprietary connectors and communication protocols to inhibit any 3rd party replacement parts, which is a crummy situation for the consumer.
@@GrinTechnologies the lack of standards for connectors and interfacing charger to battery is frustrating. Makes public charging difficult or uneconomical.
@@klang426 EM3ev only sells genuine cells with best practice BMS. I own 3 from them that i use myself and I am really satisfied even after up to 6 years they are in service now. I opened one of these and they are best on market in my opinion, even outperforming genuine the big brands in terms of structural stability. I serviced about 10 ebike batteries in my life, changing BMS or cells, so i think i know what i am talking about. EM3ev is expensive but worth every cent. I will buy again from them as soon as one of my 3 batteries dies. I dont build batteries by myself anymore since they can do the job better then me
EM3EV is in a totally different category as UPP and way more reputable than typical chinese vendors. They take all kinds of extra safety initiatives and have a much richer understanding of battery tech than almost all the other chinese pack assembly houses we're familiar with.
I have a ebike and bought a few extra batteries. Have dry chemical, halon, and CO2 . Know water is not the best for battery fires unless you have a swimming pool to put the battery into. So it will cool and take oxygen away. But not good for thermal runaway. The halon are 20 pounders. Not sure if thats enough to cool down the fire?. They sell special extinguishers that they claim are made for battery fires . But think they are just a type of halon. The CO2 is a 20 pounder also. But it is huge. So leave it outside in storage shed. But might bring it into the house were ebike is. The halon and CO2 might work but have to careful. Because they both displace oxygen. So ready to throw battery or ebike out of the house just in case. But I have to be careful of the toxic smoke it put off also. You might want to make a video on what fire extinguisher will really do work. But they should have came out with one for lithium even before they started selling batteries. But fires and thermal runaway are two different animals .
Great breakdown of a growing issue. You can charge LFP cells safely from 0-100% which removes the wh/kg advantage of cadmium based cells, so there really is little reason not to use LFP as it is far safer. Also, the fact that ebike companies have cheen charging batteries outside of a fireproof case (which are surprisingly cheap) shows just how immature this industry still is.
This post is largely misinformation too unfortunately. You can absolutely charge lithium ion 0-100% with no safety issues, and the energy density advantage is pretty massive (almost double the weight with lifepo4). I would sleep better with Panasonic liion packs than generic Chinese lifepo4 batteries at my side for sure. But if you are on the market buying generic no name stuff, definitely choose lifepo4 over regular liion
Do you have a single source that states the Li-ion batteries can be regularly charged to 100% without significantly affecting their lifespan? Because every single scientific study done on the matter states the opposite. Or is this a "trust me bro" type statement? If you are stating that Li-ion cells, by any manufacturer, are safer to charge in your home rather than a LFP manufactured by a Chinese company like CATL or EVE, you frankly should step away from the industry. No wonder youve had so many fires, you are clearly completely clueless.
Partial charging to 85% or 90% does increase the cycle life, but even charging to 100% a pack with panasonic 18650 GA cells will provide a stunningly long cycle and calendar life. Source? We've been selling packs with GA cells since 2017, both with generic 100% chargers and our Satiator that gives people an option to do partial charging. Those batteries are now going on 7 years old, and when we have opportunities to retest them from customers they are usually still giving well over 90% of their original capacity, regardless of if they are being charged all the time to 100%. The calendar and cycle life performance is well beyond what anyone had dreamed of getting. To your second paragraph, that's not what was said. What was stated is that Li-ion cells from some very specific manufacturers (eg Panasonic, Samsung) are safer and more reliable the generic LFP. If you are going with generic chinese Li-ion, then hands down that is less safe than generic LFP. Perhaps you simply misread but the exact quote in the post was "If you are on the market buying generic no name stuff, definitely choose lifepo4 over regular liion" The reason that mainstream EV companies don't use LiFePO4 cells is that they are both twice as heavy and there are no obvious top-tier manufacturers of them. There really aren't any well reputed producers of LFP cells anymore after A123 long ago went belly up.
In Frankfurt, Germany.... There's no bike certificate shop that will accept some no name bike for repair. No name ebike is for use until something is broken.... Then you can get rid of it. AND must buy something with quality, reputation and repairablilty.
And yet i love my self built LiPo battery packs, even for e-mobility. As soon you know what risks are possible, you just have to act accordingly. I charge my LiPos always where nothing can burn around it, if possible the charging battery pack is also within sight, as well a CO2 fire extinguisher in case something really bad happens. For me, LiPos are still the way to go - cheaper, much more capable of drawing a lot of power (or even charging) plus i have enough experience with them. My 48V 10Ah LiPo pack for the performance scooter does better than the original 10Ah pack with LG cells. Its performance is also significantly increased uphill. Voltage sag on the original battery was like 5-7V when drawing about 3000-4000W, with the LiPo pack with same capacity its about 2V, mainly because they are high drain racing LiPo cells allowing in this 10Ah config for like 800A long term and 1600A short term (10 seconds). In watts we talk here about 40kW nonstop or up to 80kW output for 10 seconds! The only 2 batteries which were smoking and swelling were: 1) In a picture frame a original, even DEAD (
As long as you 100% own and understand the risks and use them accordingly that's all good, but it just takes one slip up with a non-BMS protected LiPo pack to have a real spectacular situation. Sounds like you have a good handle on what you're doing but you can understand why in general we'd heavily discourage most people from contemplating that route. FWIW, the burning ebike in this video thumbnail is from a DIY LiPo battery that someone had on an ebike parked here at Grin, no BMS circuit, inadvertently overcharged. Went from a puff of smoke to 12 foot flames very quickly.
@@GrinTechnologies Yeah, i was a bit „greedy“ as well and used the old BMS instead of getting one with faster balancing i would probably need for multiple fast charges in a row. But as i used to do in the RC hobby, i love to monitor and see individual cell voltages so i have connected a LiPo checker additionally so i can control if anything gets out of balance. In my next DIY battery i will for sure get a proper and PROGRAMMABLE BMS, to set the maximum charging voltage to lets say 4,12V out of the box, hopefully with customizable CC/CV settings as well to allow for fast charging entirely to the 4,12V. Also a higher low voltage cutoff. I really avoid full charges and draining it until the BMS cuts off, in fact by reducing those limits by default, i can make sure the battery isnt even coming close to those limits (100% and 0%). A proper (oversized) battery should make up for the lost useable capacity. In fact the story you had, it should be basically CRIMINAL to use 2S or more Lithium cells without balancer or at least protection circuit for each cell. I would call this LiPo battery without balancer or protection circuit a reckless idea, danger and hazard for anything and anybody. Good thing it burned down without harming any person.
@@GrinTechnologies but i get your point, if possible i will also avoid LiPos, but high drain/low resistance LiIon cells are still expensive as hell and poor capacity such as the Samsung 25R as awesome this cell is. Would you say its better to build lets say a high drain 10Ah (2,5Ah 4P) pack or a 50% bigger one but with high capacity cells (21Ah, 3,5Ah cells in 6P). Can the doubled capacity make up good enough to maintain a useable low internal resistance in long term or should i stick to high drain/power tool cells to make sure the battery can withstand it also in some years? Thats why i use that much high drain LiPo cells… as soon they get „weak“, you KNOW they are done and need to be replaced, but until they get weak they maintain a spectacular performance incomparable to any LiIon round cell.
There are some 27100 emoli cells that are superbly good for ultra low resistance and high 'C' charge and discharge capability. But in practice, you really don't need high C cells for an ebike. I want to be able to have at least 1 hour or more of electric assist, so averaging 1C is fine and within the realm of virtually all cells. To your question, I would say hands down to build higher capacity energy cells then a low Ah pack with high power cells for a given power goal.
@@GrinTechnologies Yep i agree But i have for example a modified 2000W+ dual motor scooter with „just“ 48V10Ah battery, where those LiPos are a big advantage regarding to cycles and very short (fast going) trips.
They are super dull, literally nothing happened. The circuit interuptor stopped the current flow once the cell's internal pressure got too high and then the packs just sat there with no current.
How about ebike and scooter battery that won't charge, only in some minutes then stop? always stop at about 50% when charging and stop at about 50% when riding? only ride about 1 or 2 miles then stop.
Not that long ago, more than a few smartphone would heatup and battery would burnout in many cases user got burnt. But you didnt hear about it all that much but then again in those days, social media wasnt a thing yet. In time, smarphone battery safety improved greatly.You dont see smartphone fires anymore. Same will happen with mobility batteries. Eventually all the built-in temperature monitoring and inhibit function system safeties will prevent all possible battery overheat condition.
You actually don't see fires on properly built mobility batteries either these days. It's really mostly a feature of generic brand cells in an unregulated industry dominated by direct drop shippers from China. Sadly all "ebike batteries" get lumped into the same category. Monitoring the pack temperature won't really do anything to prevent those incidents at all, as the thermal runaway is caused internal to the cell. In those situations the BMS circuitry can observe that the packs getting hot but it can't do anything about it as it's not the result of external charge or discharge currents.
I'd need to see side by side test data to have a strong opinion. When we last tested resin potted batteries into thermal runaway during the early ligo development it didn't stop thermal runaway but it also didn't result in flames, just billowing clouds of smoke. See ua-cam.com/video/oBlac5gWLfI/v-deo.htmlsi=_IXqmhFAFaIFAEfR
We are generally very pro DIY, but when it comes to custom built lithium batteries you really really need to know what you are doing and have plenty of experience in spot welding, bms cable routing, enclosure design and waterproofing etc. We have a strict rule at grin of no DIY batteries allowed on the premises for a reason.
I believe the main cause of fires is using incompatible parts (ordering the wrong charger, wrong battery, wrong controller, etc). The other issue is people messing with it to make it go faster (there are videos on UA-cam showing people how to disconnect this or that to get more speed out of it). If you own an ebike/escooter, just use it as is. When you order parts (batteries, chargers, etc), make ABSOLUTE SURE that it’s the correct part. When I charge my escooter, I put the charger on a timer and I turn a fan on to keep the charger cool.
Unfortunately the belief you share here is not at all what our own first hand experience shows. It's true that some forms of tampering can clearly increase battery risks (eg bypassing a bms circuit), but anything else is natively protected by that very bms circuit.
The Video I've been waiting for for years. I've always wanted a competent persons perspective on ebike fires with technical background. The only people that seem to speak on these are experts on extinguishing fires not on how they start.
And you can't even really extinguish a battery fire...
I always enjoy a nice Justin lecture, high level or low level your presentations always have a good structure and are enjoyable to listen to.
Thanks for that feedback and appreciation, it's nice to hear and we can assure there will be plenty more to come
@@GrinTechnologiesstill not taking in to account the resources ,wich totally destroy the whole naratives.
Great Video with important info. Thanks
I work for QBP and provide support for FAZUA. Watching this is so amazing because I've explained so many of these topics to consumers and dealers. Great job, NAILED IT!
One thing I've done with all of my home-made batteries is to wrap them in a layer of fiber-glass fire blanket under the PVC cover. Not only does this help reduce the chance of a fire spreading, but glass is an excellent electrical insulator, and it offers an abrasion layer to protect the batteries underneath in the event of a crash.
I also use the JK-BMS. These are really nice as they have active balancing (meaning they can balance during both charge and discharge), have two temperature probes, a bluetooth GUI, and lots of programmable safety features, including over temp, under temp, short circuit, over current, over voltage, under voltage, etc.
This is all good, but nothing the bms does can make up for a situation with low quality cells that go into thermal runaway all on their own even when always kept with nominal operating conditions. So in addition to those precautions, you should still only use top tier cells, even if they cost a fair bit more per wh than generic ones.
@@GrinTechnologiesAbsolutely! I do bike touring, so last thing I want is to get stranded by a battery fire or failure. Also, in my experience top-tier batteries last longer, and so pay for themselves anyway.
Great talk Justin, I have followed you for years and am amazed at your great work. I remember when you had a contest to name the cycle analyst. I' ve had 2 fires, both my fault, no one hurt. Lipo - I hooked up a 3 series to a 4 series ? thinking I was hooking up my light. oops, then hooked negative to positive on a 4 series, in the dark again, , and I felt the heat, not a fire just a wire heated up melted the solder so that broke the connection. Now I use Li ion on my bikes, they work great. I add a lipo as a booster pack sometimes but I make sure I hook it up carefully in the light.
Lol, thank you for advice of this matter. But It is best to keep my preference of normability of my uses of all 4 of my ebikes of the extreme need of avoiding these scenes of ebike fires. I lived thru wildfires and even in my home and FIRES is a moment in life no one needs to witness of experiancing ( its total dredd ) and myself with ebike use, I rather ensure I have no need to mess with the ranges of specs. Im sure its useful to many but for me I just keep em simple. Ride safe and be safe and thanks for your experience of this matter.
Great video, seeing the stuff that OG ebikers had to deal with back in the day makes me thankful for how much easier it is now. It seems like I got interested in ebikes at the perfect time.
Love your chargers Grin =) Thanks for everything you do.
I think I'd add to your presentation the danger of leaving the battery exposed to sun on very hot days. That may cause a rise in internal temperature and subsequent explosion. Happens with GPS units stuck to the windshields of cars. That might've been the scenario in the case of the scooter by the subway station in your leading slide. Grin rocks, learning a lot from your videos.
Ah yes, that intense Canadian sun, and the blazing Vancouver summer, anything could combust under those conditions.
I mean didn't we already know this in the 80s and 90s
@@sankaplays3098 we already know alot of this information
The early days portion of this video is so fascinating to me. I got into this in 2016 and the not-so-distant past seems like such a mystery to me. Someone needs to write a book.
The ebike movement really started in earnest as a thing in the late 1990s. There was some stuff in the 1970's that never went anywhere, but by the 90's you had zap, Currie, aerovironment, heinzman, Ev warrior and a bunch of other brands setting the stage for what was to come.
@arobertson87 I got in in 2003 when the Voloci ebike from new Hampshire debut.. NIMH batteries were terrible, needed to be topped of just prior to leaving, and the sag in winter was tremendous. I hen went to NICads from Justin , heavy as heck, nd they would get super hot.
I only started in ebikes in 2014 so have the same feeling as you. I did used to race R/C cars during the Nicad & Nimh era so I know how big a step Li Ion & Lipo were :)
Great presentation! Thanks for taking the time to compile all these years of experience and distill it down to concise and coherent messages. The Grin mission in full effect and always a bit entertaining too!
Glad you enjoyed it, was something of a relief to get this all unpacked with the other conflicting messaging that we see filling the airways.
i used to fly rc helicopters and air planes with this amazing older man i had met at the flying field. He was charging his batteries one night in his garage connected to his home and one of them failed causing a fire. He had his lawn mower in the same garage with a gas can which then exploded igniting his car and eventually the rest of his home. When he told me this one day i was super shocked it just seemed like something that doesnt really happen to people you know. After losing his home and it was a very nice home his wife was so angry she left him and filed for divorce. One week later the man had a heart attack and died. It was really super sad because he was the nicest guy i had ever met and so helpful at the flying field with his knowledge of batteries and charging. Goes to show it doesnt matter how much you know about batteries they are still unpredictable and could ignite at any time for no reason. Please charge your batteries outside away from your home because once these fires start they do not go out.
Wow - such a good presentation, particularly case histories! This brings to mind something paranoid that somebody said to me years ago:
"Never charge an unknown/suspect Li-Ion battery anywhere that you wouldn't start a campfire"...
Thank you for this talk and great explanation. I’ll definitely be forwarding to my reps in nyc.
It was great to see this presentation in person. Thanks for sharing your knowledge, Justin.
I ran a hobby lipo 14s8a pack without bms but was very careful when charging it. Eventually I got a Bluetooth bms and found out that 5 of 14 cells were dropping below 2v whenever standard throttle was used, and immediately recycled the pack. Thankful I never experienced a fire, always kept the battery in an ammo can just incase
Definitely a lot of close calls that happened in between all the various actual hobby LiPo battery fires. Glad you were taking precautions, and please keep spreading the message that every lithium ebike pack (and especially a hobby grade LiPo pack) needs a BMS!
This is fantastic! It's 1 am and I can't stop watching! Thank you for sharing and hope to meet you some day!
Fantastic talk! I hope the regulations don't make ebikes even more unafordable. Wish there was a way for governments to just ban the sale of unapproved cells.
I just finished building a custom full suspension commuter ebike and it was one of the most fun/rewarding projects I have ever done. Ripping over all the speedbumps here in Vancouver has never been more fun
🙃
governments banning the sale of unapproved cells will increase smuggling to the same markets to meet the growing demand.
Very good presentation.
Ryobi has been using Chinese EVE 18650's for about 4 years. Power tool fires do happen, but yes they seem quite rare for how many power tools are out there and how much they get abused. Speculation is: the energy density of cells used in power tools is far lower, 1.5 or 2Ah, compared to 3-3.6Ah used in some ebikes. Lower energy density means less flames, gas, and heat are emitted (non-linear), less chance of thermal runaway. Add to that the cells have high discharge ratings, so should heat up less and hopefully designed to age better.
A major concern with cheap Chinese packs is not the brand of cell used, but that they can be using recycled mixed cells that are poorly matched. You might have a pack with an old, lower capacity, high ESR cell right in the middle. That one is going to get hammered, and probably start heating up the most. For a BMS to handle that failure you'd have to have a probe on every cell which is not realistic.
Also lack off liability through addressable supply chains gives NO incentive not to compete on price alone, multiplying flaws and risks.
Yeah, Most power tools uses Texas Instruments BMS chips. And not using High energy density cells, they using high current cells.
Why is that not realistic? A thermal probe is less than a dollar. Also, the BMS should in most cases be able to identify the cell by voltage difference/current on the balancer.
@@llejk Have you ever constructed a pack before? Manually soldering and running probes is a huge pain in the ass and will drive up the cost. The BMS doesn't care about the voltage difference unless its exceeded the min or max voltage, at which point it shuts off. Its not going to know a cell is in a hotspot, and even if it does, you'll just get constant nuisance trips.
as an RC pilot I learned all about how to keep your stuff from exploding in flight or while charging.. the hard way. And I always just assumed that the same kind of mistakes (maybe even intentionals) were being made in ebike factories. And that's what this video pretty much says! You can get the entire battery and charging system for less than half the price if you take out all the designed-in safety features, and there are manufacturers out there serving that market.
Timely video, thanks. I am just a newbie in ebikes. My first effort is a rebuild/upgrade. The new battery is coming from a company that seems to have a good and long term rep; worst being that the battery is less powerful than described, the company seems responsive to these complaints. The final check in their favour was that this battery was designed to make the most out of my specific battery enclosure.
THANK YOU for this detailed, necessary presentation. It gives me peace of mind because my 2 wheel drive E-CELLS Super Monarch Crown uses 2 SAMSUNG batteries, 15 Ah and 20 Ah. (Downtube and under rear rack). I'm not surprised that Dave Clevelend, the designer of E-CELLS e-mountain bikes, uses SAMSUNG because all of his components are high quality.
-> Actually lithium iron phosphate batteries weigh only about 20% more than Li-ion batteries of equal power but have TRIPLE the charge/discharge life to any chosen %.of maximum charge relative to its new state of 100%.
Excellent video, i have holding off on the ebike because of the fire risk. I found it difficult to understand this issues and why these were happening and this is exactly the kind of information i needed.
You fail to mention UA-cam video's being posted of amateurs building DIY lithium batteries packs also upgrading chargers so they charge faster. Not only are they putting themselves at risk also other from lithium fires. The whole industry in sales and repairs needs regulation, so standards can be increased.
Agreed that the proliferation of YT vids encouraging DIY battery assembly encourages a lot of people to do things that they shouldn't. Part of the reason is that there is zero ebike
service and repair industry and the ebike manufacturers do everything to discourage a healthy aftermarket,leaving no option than DIY repair.
Re faster charging, There is generally no problem charging lithium cells up to 0.5C charge rates, while most stock chargers are only like 0.2C or less. So upgrading to a faster charger is quite a reasonable thing to do as long as the actual connector type on the port supports it. This is not a battery fire risk.
My bike is extraordinarily unlikely to combust, because I’m the battery and the motor. By the time I’m old enough to need an e-bike I hope they’ll have the battery tech figured out. But the crappy fuses and bad construction are going to be with us as long as there’s a profit incentive
I’ve purchased ebike batteries from china, and i was dismayed at the poor construction build…balance wires crossing over the top of the cells, without adequate insulation, and poor support for the cells, allowing them to move, and chaffe inside the case…a timebomb ready to go off.
Great video, definitely an issue that needs wider promotion and education for the consumer. Love your work Grin Tech!
Thanks Justin! Great coverage of a nuanced topic.
Great talk. Lots to consider in building my next diy bike. Current bike uses a pack from Epower and i shopped on price not really knowing all the details.
Lets say you keep your battery at around 20% charge when you're not intending on using it.
Does it stand to reason that further decreases the chance of a cell suddenly catching fire? (would a battery at 80% charge be more likely to catch fire then a 20% of the same bat?)
Another question: what are the chances Lithium ion battery's from hand held gaming consoles that haven't been charged up in 10 years to make a fire ? (asking since I have an old psp, and a nintendo DS, and a couple of old samsung batteries around) - I never realized being undercharged/empty could be a hazard too - should I just get rid of these?
Being undercharged in itself is not a hazard. It's just if you attempt to charge a battery that is super discharged (like
@@GrinTechnologies Thanks for the great answer man - appreciate your time doing this.
Excellent Presentation I learnt alot especially about not using ABC fire extinguisher thanks
Trouble is without regulation, people learn that late
What I would suggest is to charge your Li battery inside a closed self cleaning oven. My thinking being that these ovens can handle 600⁰ F temps or higher. Also charge the battery when your are awake and in your living place. This being advice for most appartment residences. Another method is charging the battery in metal trash can in a safe area. Feed back me if you have any ideas on what i just suggested.
I've been charging my ebike battery inside my oven for quite a while now. I also babysit while it's charging, and make sure it's unplugged as soon as it's done.
Charcoal grills are another common idea
Brilliant presentation. Thank you.
Excellent video with tons of useful information. Thank you.
Thank you for this great presentation. It is shocking how hard this information presented here is to find. I dabble with DIY ebikes, I use reclaimed A123 batteries. They seem very stable. I take a hit in capacity and weight, but have huge gain in amperage both charging (4C) and discharge, and safety
The original A123 cells were really one of a kind, most of the inexpensive lifepo4 available now doesn't come close to matching the ruggedness and C rate capabilities of those old cells. So yeah, if you don't mind a hit on weight those are some great building blocks.
Good Job Justin and thanks for sharing.
Nice informative presentation. It's easy to listen and understand your talk. Freegen hub when?
About overdischarging: This will probably not immediately damage a cell. If you leave it around for days or weeks, then it will damage the cell by chemical processes. If you recharge it immediately, then probably not much will happen.
For security I store my battery in a large ammo box, together with some liters of water in plastic bottles. You need about 600 Wh to vaporize 1l of water.
And about 90 Wh is needed to heat 1l from 20°C to 100°C.
So I hope, this will stop a fire as early as possible.
again a great video Justin, thank you so much for putting together and presenting all this information in such a clear and entertaining way
I'm glad to see Grin having this conversation and taking battery safety seriously. I was working in Ebike product development for a manufacturer in Seattle, and was in fact a Grin customer. When I took on that project let's just say things weren't well understood, and in fact dangerous. I pressed for standardization and increased safety measures, ultimately coming to the conclusion that in the future these batteries, BMS, and chargers should be certified by the U.L. I would go further to say that the BMS is not capable of monitoring individual cells, instead it tracks a parallel bank of cells. Should one of these cells be faulty it can lead to over charging of other cells on that circuit.
Realistically its people buying cheap, or scam batteries, which then have very cheap BMS's that in turn cause a disabalance and then have the cells explode.
People should stop wanting to buy 48v 20 ah batteries for 150 euros or dollars, its not realistic, and will get you burned.
Indeed, BMS just tracks parallel cell groups. In our experience, the individual faults of a cell in that group are either:
1) Disconnection from the group, (eg from a bad tab weld or an internal disconnect within the cell can). This results in that group having less capacity than the other parallel groups, and during charging it will reach full charge first. The BMS circuit should stop the charging once that cell group voltage is high, but if the BMS circuit fails at its task, or someone charges from the discharge port where there is no overcharge protection, then it result in overcharging as you say.
2) Internal soft short. In this case, one of the cells has an anomalously high self discharge rate and drains the parallel cell group faster than the BMS is ever able to balance it, eventually resulting in this group all getting discharged to 0V. The BMS circuit in this scenario should prevent both the charging and discharging of the pack. If it is charged in a way that bypasses the BMS charge cutoff mosfets, then all the _other_ cell groups in the pack get slightly overcharged.
@@GrinTechnologies In the event a faulty cell or connection should become faulty there is not usually an indication to the end user that such an issue exists, they simply wait for the LED on the charger to turn green, perhaps notice a subtle reduction in range if they frequently check. But few do. It really needs to be black and white for the end user. I'm sure you're focused on the same things.
Lol, i have 3 of the ezee battery packs. And i bought then in 2019 😮. So far so good
Those pack are just great. All the instances here were from like 2014 or earlier, when both the cells and the overall assembly techniques were not at the same level
Awesome talk Justin! I was expecting to hear about battery storage (ie metal containers to prevent fire spread) used during charging. Great info about buying named brands and avoiding issues in the first place. Thank you!
If you aren't confident in the source of your cells then charging in a place where fire would be contained and can't propagate is certainly a good idea. But with good cells and a good bms, this kind of step is hardly necessary.
We're not a fan of either bosch or Shimano propriety systems, but they have 10's of millions of ebikes out there with no one charging in a metal box and no one having fire issues either.
That was a really good slow build to a conclusion I thoroughly agree with. Standards don't necessarily make things safer through Engineering but through keeping out small guys. While this may be good if there's no innovations yet to be found it kinda kills off innovation which is frustrating for us backyard tinkerers.
Great information people need to study and understand instead of just guessing.
Thank you so much for this video Justin ! Very interesting and useful !
As long as the UL2271 will NOT adress the cell spacing or Thermal Energy Absorbing Material between cells the UL will mis the goal ! Thermal runaway is one thing but thermal propagation is also VERY IMPORTANT. I have this document and revised it completly and from now it will help but not help the best as it could.
So detailed and to the point. It's an important conversation as ebikes are getting more popular.
It is always such a treat hearing Justin speak.
Well do and thank you.
What is the UL, NFPA, FM and NEC standards regarding Lithium batteries including charging and storage and do these need to be addressed
thank you so much for this video. i appreciate the informed and educated information.
Fantastic presentation as always Justin
Failure sources:
- R/C flight hobbyist lithium-polymer batteries out-performing gas for power, range - 7:44
[is this due to scale inefficiencies of small gas engines? could a micro diesel power plant driving main horizontal thrust prop + electric vertical-take-off and control rotors work efficiently? How does electric vs. gas scale to human flight machines?]
- Water facilitating galvanic current between cells and through casing to cells
- Tab weld failure 16:30
- Tab material overloaded 16:55
- Mechanical impact 17:20
- BMS circuit failure - electrical overheating within internal pack circuitry burns polymer casing materials = electrical not lithium fire
Failre Consequences
- eBike business fires 19:50
- eBike business fires (home auxiliary facilities) 20:50
Small Cell Packs > Large Cell Packs
- easier to locate issues within pack
- industry convergence on 1850 type cells pushed development and standardization for small cells
- allows more granularity for overall form factor of battery pack
- 1850's vary in quality / China market includes lots of counterfeit
BMS DETAILS
What is the problem the BMS solves? ~ 24:30
- eBike end user doesn't attend to any of it -- the management is baked into the battery -- down to each cell in the pack.
- BMS and maintaining 1850 standardized-cell specks 25:10
- What are consequences of out-of-spec charge/discharge for battery cells ('cracking' the case/BMS to recycle individual cells)
29:00 -- testing indicates it's nearly impossible to use consumer methods result in fire. End users can't do it. Fires are defects (or extreme mechanical)
CONCLUSIONS
- 31:05 -- safety demands decades-long R&D / product evolution of a large company's small cells (1850's), ensuring safety even in extreme abuse cases, down to the cell level (BMS, internal circuitry all prone to various failure modes).
- 32:50 -- cordless power tools do have fires, but rate is minimal -- and it's likely because typical consumer buys name-brand tools with proven cells in their battery packs
- 31:50 -- we need incident reports to indicate the brand cell involved in fires
UL listing now required in NYC- 34:15
- Doesn't require proven battery cells -- Samsung, Panasonic, LG
- Forces massive cost to sell an eBike battery or whole eBike setup - $40,000 per battery design to go through UL testing
How To Extinguish - 39:09
Run-away heating drives lithium battery fire
- Water = yes: quench the heat
- CO2 extinguisher (not common household) extinguishes flame and cools
- Chemical ABC extinguishers (typical household) make a mess and won't address internal heating that restarts the fire
Thanks for creating and sharing the summary!
thanks for the info I wonder how the bms works and its malfunction of the energy in the batt
Bms circuits have sense leads to all of the cell connection points, which means a failure that shorts those leads together can result in very high discharge currents in pretty thin gauge wires
Good video. Thanks. Cleared the air on a lot of issues.
I have many ebikes on my channel. Batteries strapped on . i need to upgrade
Great presentation, thank you.
Good Talk, Very Insightful!👍 btw Peter is my hero,🦸♂️ and has my eternal ♾️ gratitude 🙏 for fixing my Frankenrunner! 🥳 🎊 🇨🇦 🤗
Grin does some great vids on various topics.. I am surprised they only have 25k subscribers
my ebike battery always stopped working quickly and was charged quickly.
it was an 8s 24V lifepo4
the BMS only looked at the first 3 cell groups, which was fortunate because the 2nd and 3rd series were defective due to corrosion
1V and 2V and the rest 3.7V
Thank you. Before watching this video, I had decided I want an ebike. Halfway through this video, I had changed my mind, deciding maybe I did not want an ebike. By the end of this video, I've decided, yes, I do want an ebike, BUT I now intend to have a CO2 fire extinguisher as well... and will never, ever, ever walk away from a charging battery. Heck, after this, I won't even charge my flip phone without supervision. It seems to me, this battery industry is in serious need of some worthwhile regulations, controls, or checks & balances. Safety first. A cheap battery is nothing next to the price of a home... or skin grafts... or a funeral. The bucks saved are not worth it. Peace of mind is an amenity that will sell. Somebody needs to step up and make that amenity happen, even if it means complete manufacture of the battery, start to finish - no outsourcing or importing anything beyond raw ingredients. Clearly, there's a market for that. Until then, seems like getting an ebike will be like playing Russian roulette. Maybe, they should all be charged in the middle of the yard, with a 100-ft extension cord, and housed in an outside shed (or kiln), custom built with climate controls. My, my, it just gets more and more expensive to have a battery with cheap components. Where is supply and demand in this? I want better. I'm sure most others do as well. If not addressed, people will stop getting electric bikes, because, if they haven't done so already, insurers will bilk or cancel ebike owners' homeowner's policies due to the risks. That, or they'll just start denying claims for losses of and to homes, other people's property, and actual people. Ouch! And renters...? Sounds like grounds for eviction to me, like boiling gasoline on the stove or having a meth lab on premises. So, yeah, I would pay for safety, regulation, controls, and a spot-on final product. Until we have it, I will equate the ebike to a Ford Pinto. What a shame.
You should have no real fears on concerns about having an ebike that uses quality grade cells on the pack contruction. They are insanely reliable and robust these days. The Sanyo / Panasonic GA cell should be crowned as a superhero in that regards. Your life will be massively improved by having an ebike, and your risk of fire from conventional sources (toasters, heaters, bad household worrying etc) will be much hight than from the pack.
The risk is buying a cheap generic ebike which cells of unknown provenance. Then you do introduce quite an unknown element of risk
@@GrinTechnologies Thank you for the response. That makes me feel a bit better about getting one. I'm looking at the Lectric ebikes - they make one that folds for tiny living spaces. I now like the idea of that battery being inside the bike frame. People tell me they are good ebikes. But... think I'll still get one of those extinguishers to have on hand, just in case. It's bound to be cheaper than my deductible - LOL.
There are also lithium battery charging safe boxes that you can buy. Though there's also a possibility they can spontaneously combust, so you'd have to take them off and put it in the box whenever you are storing it at home, if you want to be completely safe.
How about Sodium-Ion batteries for eBikes?
I think I would be happy with a reduced range because I only do short journeys at a time (between 1 and 4 miles).
I'm sure in densely populated areas many people would be happy with a shorter range but with the benefits of Sodium ion tech.
With good investigation technique, The real cause of these fires should be VERY easy to track down with basic statistical analysis. It may not even be the batteries themselves but the controllers they're connected to. We need to focus on BMS technology. I have a pack from a hover board that I couldn't destroy if I wanted to because it has overcurrent /short circuit and over/under-voltage protection 3.2 to 4.15v. I suspect most consumer packs are like this. This could also be caused by bad chip programming within the BMS. The charger used shouldn't matter if the BMS is well designed. I've been a lithium battery collector for a while and haven't had a single fire or even an overheating condition. I always charge my cells to the right voltage using the factory charger and quality hobby chargers with lithium battery settings. The fires I hear most about are from racing drones with their unprotected pouch cells being physically damaged over and over. None of my drone packs ever gave me issues aside from the occasional cell going bad. If not for the internet or media, I would have never known of lithium battery fires. I think it's far less common than the media would have you believe. The media loves sensationalism and lithium fires make for juicy content. Don't buy cheap cells and only trust Sanyo, Panasonic, Sony, Samsung or LG cells. Most other brands are hot garbage from China (a country who both relies on us economically and hates us politically). I think Samsung and Panasonic are the best but that's a battle I won't fight.
Thanks for your perspective. It's unfortunately that the fires themselves almost always destroy the all evidence as to what sequence of things caused it. But all the circumstantial evidence with ebike battery fires (hobby RC is a totally different scenario) suggests that most of the fires are not the result of faulty chargers or faulty BMS circuits, or customer misuse, but faulty cells.
It doesn't matter how good your BMS circuit is at preventing overcharging or overdischarging, if a cell develops an internal short circuit and goes into thermal runaway because of poor process control and QC by the cell manufacturer, then your hoverboard pack can be just like the 100's of others that burst into flames during normal use.
Agreed 100% on your final statement too!
Fantastic video!
Always informative, thanks.
Much appreciated as always.
Camera Overheating Use External Battery, cooler like small fan or cooling pad (no noise), lower ISO and most common is mismatched SD card class rating for video being recorded.
The company has a great reputation on the streets, ethics guru Louis Rossman called it "freedom tech" , high praise indeed
The sad thing is that because of these early hazardous batteries a lot of public transit will not allow any electric mobility devices on their services meaning the promise of connected transit needs to wait until they can be sure that all of the old cells are out of circulation, which could take years.
using a proven battery is a good idea. I’ve built battery packs from scratch, with success, however, I have found after years of testing, that tool batteries, such as dewalt, can be used with great success. Custom building a rack, to hold these batteries securely, and to multiply voltage to the desired value….and likewise, parallel to increase capacity. The only downside, is that batteries must be removed to be charged individually on its own charger. But, for safety, and long lasting durability, this does work well. Still using an ebike after 10 years with this setup, a hubmotor and controller from Justin’s ebike store👍, and 9 dewalt 20 volt batteries in a 3s and 3p configuration, that clip into a rack that fit securely inside the bike’s triangle frame, resulting in a 60 volt 12 amp/hr pack. I charge all the batteries full before inserting them into the rack, so there is no voltage difference between batteries. Reliable, predictable performance. 3 chargers can get all nine batteries charged and ready to go again in 3 hours👍. Thanks for the video! cheers from northern BC🇨🇦
Great video. Do the batteries you make have a fuse in line with the charging circuit? If not why? Do your batteries have the ability to monitor via bluetooth/app? Could not find this info on your website.
Some BMS (so-called Smart BMS) will monitor the parallel cell groups in the battery via blutooth. You can detect odd behaviours very easily with these, without having to rip apart the battery.
No denying the early Chinese Li-Ion and Li-Po battery tech wasn't exactly safe to use. I had some bad experiences when I tried to adopt them for R/C cars. I waited a good long while for the Tech to progress before I could start trusting them again. Also educating myself on proper care and charging for Li-Po/Li-Ion went a long way. Nothing like Ni-MH that I was familiar with.
Hi,
Thank you for this video.
I just received an old electric scooter and an ebike, im looking into upgrading their motors, battery setup.
Glad i came across your video.
Every so often you'll see on the news about house fires starting from overloading or charging batteries killing family members.
This might be a dumb question, but do you recommend any companies where they do have a reliable diy kits for my projects?
Again, thank you for this informative video.
Probably saved my home from Any future fires caused by buying batteries or counterfeit.
Grin is still around?!??!?
Holy sh*t
excellent video
WE LOVE YOUR VIDEOS!!
thanks for a great talk! \My bike uses Molicel INR-18650A cells, hopefully ok!
Molicell is an interesting player. At one point 20 years ago they were among the early leaders and did cell production near here in Vancouver. I know early on they had fire incidents, we don't hear too much about them now
@@GrinTechnologies They are still located in Burnaby AFAIK
They are for R&D, but all manufacturing went overseas a long time ago, partly to shield from liability after they had fire issues (I had a friend who worked in the plant back in the early 2000's)
@@GrinTechnologies Yes, the production facility is in Taiwan.
Specs are labeled for a reason, to prevent one of the components from overheating. Its why I NEVER use a battery of placing on a controller a range of 36 to 48 ( 52v ok for 4b benchmark ) of my batterie at 60v or higher. As long as I KEEP ALL THE SPECS IN RANGE AN USING PROPER Volt's AND WATTS ,I ll be well safer than sorry as FIRES are NO JOKE ( wildfire survivor ) and NEVER RISK using components away from the spec range, its there for this reason alone.. Also CUTTING WIRES TO INCREASE SPEEDS is a SERIOUS NO NO, time will catch up with doing this for sure.
The nominal published ebike component specs in many cases are meaningless, especially with regards to voltage and power ratings. With regards to cell specs, even if you use the cell entirely within manufacturers guidelines, the risk of a spontaneous thermal runaway is always present with generic grade cells. Your recommendations here seem relevant but largely miss the point. Most ebike battery fires have nothing to do with using components outside of their spec.
Thanks for the video. I have a 10 year old Lifep04 battery. How old is too old? Should I recycle it before I have any issues? What about Lithium ion 18650s?
Is Grin going to produce their own batteries again? I liked the idea of every cell being monitored vs a string of cells.
Lifep04 I feel are more safe and Last much longer , also I soldier the ring terminals
Note that there are no problems with Lithium Iron Phosphate chemistry batteries. Industry just doesn't use them because they are slightly larger batteries than lithium ion batteries 😢
We dealt with 5 different manufacturers of lifepo4 ebike battery packs back in the day (both in cylindrical and prismatic cells), and none of them had even close to the reliability or the cycle and calendar life we see with the current leading brands of li-ion.
Would love to know how modern lifepo4 has kept up, but since A123 left the scene many years ago there doesn't seem to be any respectable manufacture of LFP cells in the caliber of Samsung, Panasonic etc
Even at double the weight it still could have widespread use as an intrinsically safer alternative for sure.
@@GrinTechnologies they have gotten much better than the early days. But the main problem is with how they are being charged still. I built my own LiFePo4 pack three years ago for my ebike, and the capacity got better and has not demished at all. But the key to my success has to do with unidirectional impulse charging that uses little current so does not heat up the batteries at all, even though it is delivering 1 amp impulses at Mhz speeds. Its a method that can't be used on lithium ion because they are real finiky and likely explode. This method was invented by John Bedini for lead acid batteries, and the LiFePo4 ended up working great with it too. Unfortunately he passed, and not many of the battery chargers out there, and few of us are out here that understand it enough to build our own.
I've got a lifepo4 from 2019 that I am only now retiring because the voltage is dropping. There's no reason for most people to use a li ion battery on a bike in 2024. Lifepo4 is plenty powerful and lightweight. The tradeoff is completely foolish now.
Very informative video 👍🏼
Damn. As a ebike diy guy i am quite disappointed. I thought it was because of the charge/discharge protocol. But now he says its about the bad cookie in the lot that does a thermal runaway due to dendrite formation.
This is so sad because i have so many batteries laying around.
I realise my practise is unsafe.
However i did manage to get thermal runaway by charging a overdischarged 18650. The reason this battery was flat probably is the dendrites: self discharge during charging= thermal runaway.
That's certainly what all the evidence points too. We're normally huge DIY advocates for those with the skills, but with lithium batteries the unknown risks inside the cells are just too great. If you are doing it, you should really only work with new top brand cells. Save the recycling / repurposing of used lithium cells to stationary power applications or other scenarios that can be properly quarantined.
really helpful video!
Shouldn't UL2271 compliance be the task of the manufacturer rather than the reseller?
Luckily battery quality and chemistry has greatly improved over the years, now we have chemistries like lfp, lto and sodium ion is starting to come to market that are much more stable
You can find demonstrations on youtube of destructive testing of lto cells that are incredibly boring, but lfp is the best balance between volatility capacity and ampacity in most cases
There's an eBike battery sold in the UK that has been banned. Called UPP, it's in a triangular shaped pack that straps to the bike frame.
It was sold on Amazon, eBay etc in the UK.
Trouble is the authorities (OPSS) banned them on the big online platforms but the product was still sold from smaller online retailers.
Just did a search and it's still being sold.
They have caused a number of fires, and have a poor BMS (maybe non existent).
UPP is just one of a hundreds of overseas battery builders that sell direct to consumer in the west but don't have any accountability or liability in the same way that a western based company does when things go wrong. As long as that's allowed to be the case, then the competitive landscape is stacked heavily against the emergence of a reputable aftermarket battery business where only responsible players are involved, ie those who take responsibility and liability for what they sell.
Unfortunately this also incentivizes companies that make products which use lithium batteries to create all kinds of proprietary connectors and communication protocols to inhibit any 3rd party replacement parts, which is a crummy situation for the consumer.
@@GrinTechnologieswould you place EM3ev in the same category as UPP? Or are they more reputable?
@@GrinTechnologies the lack of standards for connectors and interfacing charger to battery is frustrating.
Makes public charging difficult or uneconomical.
@@klang426 EM3ev only sells genuine cells with best practice BMS. I own 3 from them that i use myself and I am really satisfied even after up to 6 years they are in service now. I opened one of these and they are best on market in my opinion, even outperforming genuine the big brands in terms of structural stability. I serviced about 10 ebike batteries in my life, changing BMS or cells, so i think i know what i am talking about. EM3ev is expensive but worth every cent. I will buy again from them as soon as one of my 3 batteries dies. I dont build batteries by myself anymore since they can do the job better then me
EM3EV is in a totally different category as UPP and way more reputable than typical chinese vendors. They take all kinds of extra safety initiatives and have a much richer understanding of battery tech than almost all the other chinese pack assembly houses we're familiar with.
I have a ebike and bought a few extra batteries. Have dry chemical, halon, and CO2 . Know water is not the best for battery fires unless you have a swimming pool to put the battery into. So it will cool and take oxygen away. But not good for thermal runaway.
The halon are 20 pounders. Not sure if thats enough to cool down the fire?. They sell special extinguishers that they claim are made for battery fires . But think they are just a type of halon.
The CO2 is a 20 pounder also. But it is huge. So leave it outside in storage shed. But might bring it into the house were ebike is. The halon and CO2 might work but have to careful. Because they both displace oxygen.
So ready to throw battery or ebike out of the house just in case. But I have to be careful of the toxic smoke it put off also.
You might want to make a video on what fire extinguisher will really do work. But they should have came out with one for lithium even before they started selling batteries. But fires and thermal runaway are two different animals .
Great breakdown of a growing issue. You can charge LFP cells safely from 0-100% which removes the wh/kg advantage of cadmium based cells, so there really is little reason not to use LFP as it is far safer. Also, the fact that ebike companies have cheen charging batteries outside of a fireproof case (which are surprisingly cheap) shows just how immature this industry still is.
This post is largely misinformation too unfortunately. You can absolutely charge lithium ion 0-100% with no safety issues, and the energy density advantage is pretty massive (almost double the weight with lifepo4).
I would sleep better with Panasonic liion packs than generic Chinese lifepo4 batteries at my side for sure. But if you are on the market buying generic no name stuff, definitely choose lifepo4 over regular liion
Do you have a single source that states the Li-ion batteries can be regularly charged to 100% without significantly affecting their lifespan? Because every single scientific study done on the matter states the opposite. Or is this a "trust me bro" type statement?
If you are stating that Li-ion cells, by any manufacturer, are safer to charge in your home rather than a LFP manufactured by a Chinese company like CATL or EVE, you frankly should step away from the industry. No wonder youve had so many fires, you are clearly completely clueless.
Partial charging to 85% or 90% does increase the cycle life, but even charging to 100% a pack with panasonic 18650 GA cells will provide a stunningly long cycle and calendar life. Source? We've been selling packs with GA cells since 2017, both with generic 100% chargers and our Satiator that gives people an option to do partial charging. Those batteries are now going on 7 years old, and when we have opportunities to retest them from customers they are usually still giving well over 90% of their original capacity, regardless of if they are being charged all the time to 100%. The calendar and cycle life performance is well beyond what anyone had dreamed of getting.
To your second paragraph, that's not what was said. What was stated is that Li-ion cells from some very specific manufacturers (eg Panasonic, Samsung) are safer and more reliable the generic LFP. If you are going with generic chinese Li-ion, then hands down that is less safe than generic LFP.
Perhaps you simply misread but the exact quote in the post was "If you are on the market buying generic no name stuff, definitely choose lifepo4 over regular liion"
The reason that mainstream EV companies don't use LiFePO4 cells is that they are both twice as heavy and there are no obvious top-tier manufacturers of them. There really aren't any well reputed producers of LFP cells anymore after A123 long ago went belly up.
Good
In Frankfurt, Germany.... There's no bike certificate shop that will accept some no name bike for repair.
No name ebike is for use until something is broken.... Then you can get rid of it. AND must buy something with quality, reputation and repairablilty.
Hey Justin, have you heard of the new Segway p100 fire on Reddit? Should I be scared of the Chinese cells used in my max g2? What can I do?
And yet i love my self built LiPo battery packs, even for e-mobility.
As soon you know what risks are possible, you just have to act accordingly. I charge my LiPos always where nothing can burn around it, if possible the charging battery pack is also within sight, as well a CO2 fire extinguisher in case something really bad happens.
For me, LiPos are still the way to go - cheaper, much more capable of drawing a lot of power (or even charging) plus i have enough experience with them.
My 48V 10Ah LiPo pack for the performance scooter does better than the original 10Ah pack with LG cells. Its performance is also significantly increased uphill. Voltage sag on the original battery was like 5-7V when drawing about 3000-4000W, with the LiPo pack with same capacity its about 2V, mainly because they are high drain racing LiPo cells allowing in this 10Ah config for like 800A long term and 1600A short term (10 seconds). In watts we talk here about 40kW nonstop or up to 80kW output for 10 seconds!
The only 2 batteries which were smoking and swelling were:
1) In a picture frame a original, even DEAD (
As long as you 100% own and understand the risks and use them accordingly that's all good, but it just takes one slip up with a non-BMS protected LiPo pack to have a real spectacular situation. Sounds like you have a good handle on what you're doing but you can understand why in general we'd heavily discourage most people from contemplating that route.
FWIW, the burning ebike in this video thumbnail is from a DIY LiPo battery that someone had on an ebike parked here at Grin, no BMS circuit, inadvertently overcharged. Went from a puff of smoke to 12 foot flames very quickly.
@@GrinTechnologies Yeah, i was a bit „greedy“ as well and used the old BMS instead of getting one with faster balancing i would probably need for multiple fast charges in a row. But as i used to do in the RC hobby, i love to monitor and see individual cell voltages so i have connected a LiPo checker additionally so i can control if anything gets out of balance.
In my next DIY battery i will for sure get a proper and PROGRAMMABLE BMS, to set the maximum charging voltage to lets say 4,12V out of the box, hopefully with customizable CC/CV settings as well to allow for fast charging entirely to the 4,12V. Also a higher low voltage cutoff.
I really avoid full charges and draining it until the BMS cuts off, in fact by reducing those limits by default, i can make sure the battery isnt even coming close to those limits (100% and 0%). A proper (oversized) battery should make up for the lost useable capacity.
In fact the story you had, it should be basically CRIMINAL to use 2S or more Lithium cells without balancer or at least protection circuit for each cell.
I would call this LiPo battery without balancer or protection circuit a reckless idea, danger and hazard for anything and anybody. Good thing it burned down without harming any person.
@@GrinTechnologies but i get your point, if possible i will also avoid LiPos, but high drain/low resistance LiIon cells are still expensive as hell and poor capacity such as the Samsung 25R as awesome this cell is.
Would you say its better to build lets say a high drain 10Ah (2,5Ah 4P) pack or a 50% bigger one but with high capacity cells (21Ah, 3,5Ah cells in 6P).
Can the doubled capacity make up good enough to maintain a useable low internal resistance in long term or should i stick to high drain/power tool cells to make sure the battery can withstand it also in some years?
Thats why i use that much high drain LiPo cells… as soon they get „weak“, you KNOW they are done and need to be replaced, but until they get weak they maintain a spectacular performance incomparable to any LiIon round cell.
There are some 27100 emoli cells that are superbly good for ultra low resistance and high 'C' charge and discharge capability. But in practice, you really don't need high C cells for an ebike. I want to be able to have at least 1 hour or more of electric assist, so averaging 1C is fine and within the realm of virtually all cells.
To your question, I would say hands down to build higher capacity energy cells then a low Ah pack with high power cells for a given power goal.
@@GrinTechnologies Yep i agree
But i have for example a modified 2000W+ dual motor scooter with „just“ 48V10Ah battery, where those LiPos are a big advantage regarding to cycles and very short (fast going) trips.
Where can we see those firetesting videos?
They are super dull, literally nothing happened. The circuit interuptor stopped the current flow once the cell's internal pressure got too high and then the packs just sat there with no current.
How about ebike and scooter battery that won't charge, only in some minutes then stop? always stop at about 50% when charging and stop at about 50% when riding? only ride about 1 or 2 miles then stop.
You can have that in the case of extremely bad cell balancing. It's worth having that pack examined by the shop you purchased it from.
Not that long ago, more than a few smartphone would heatup and battery would burnout in many cases user got burnt. But you didnt hear about it all that much but then again in those days, social media wasnt a thing yet. In time, smarphone battery safety improved greatly.You dont see smartphone fires anymore. Same will happen with mobility batteries. Eventually all the built-in temperature monitoring and inhibit function system safeties will prevent all possible battery overheat condition.
You actually don't see fires on properly built mobility batteries either these days. It's really mostly a feature of generic brand cells in an unregulated industry dominated by direct drop shippers from China. Sadly all "ebike batteries" get lumped into the same category.
Monitoring the pack temperature won't really do anything to prevent those incidents at all, as the thermal runaway is caused internal to the cell. In those situations the BMS circuitry can observe that the packs getting hot but it can't do anything about it as it's not the result of external charge or discharge currents.
@@GrinTechnologies
It doesnt just monitor. It shuts off the device and makes it almost idiot proof that's a good thing. Humans are idiots.
What is your opinion on the rad power bikes safe shield battery that's a fully resin potted battery
I'd need to see side by side test data to have a strong opinion. When we last tested resin potted batteries into thermal runaway during the early ligo development it didn't stop thermal runaway but it also didn't result in flames, just billowing clouds of smoke. See
ua-cam.com/video/oBlac5gWLfI/v-deo.htmlsi=_IXqmhFAFaIFAEfR
Any thoughts on the safety of diy batteries? I was thinking of making one for my diy ebike project.
We are generally very pro DIY, but when it comes to custom built lithium batteries you really really need to know what you are doing and have plenty of experience in spot welding, bms cable routing, enclosure design and waterproofing etc. We have a strict rule at grin of no DIY batteries allowed on the premises for a reason.
Okay! Good to know. Thanks for the response. @@GrinTechnologies
love my lifepo4
Now to make a "drop tower" to remotely puncture one of those old cells and manually create a fire to put out...
We still have a 55 gallon bucket full of old batteries and cells to play with. The puncture tests could happen yet.
@@GrinTechnologies 😁
I believe the main cause of fires is using incompatible parts (ordering the wrong charger, wrong battery, wrong controller, etc). The other issue is people messing with it to make it go faster (there are videos on UA-cam showing people how to disconnect this or that to get more speed out of it). If you own an ebike/escooter, just use it as is. When you order parts (batteries, chargers, etc), make ABSOLUTE SURE that it’s the correct part. When I charge my escooter, I put the charger on a timer and I turn a fan on to keep the charger cool.
Unfortunately the belief you share here is not at all what our own first hand experience shows. It's true that some forms of tampering can clearly increase battery risks (eg bypassing a bms circuit), but anything else is natively protected by that very bms circuit.
Nice..I subscribed