Just curious: if you wanted to do something like that, but prevent a... thermal event, how would you protect an experimental battery realistically? Build a brick enclosure? A fire safe?
If you have the space for it, just put it outdoors 5' from anything flammable and you're good to go. This is not a hobby for folks in apartments unfortunately.
I've had one of my DIY ebike batteries short and fail spectacularly at near full charge and was able to push it with a broom out of the garage into the driveway before any damage was done. Now I have a bench with wheels that I can take into the driveway for initial testing.
At least not neighbors likely to be alarmed when their neighbors run out of their garage at odd hours of the night, pushing a flaming cart and screaming "fire!"...
Current building regulations in the UK are moving towards outside storage of batteries now because of NMC's having a high tendency to combust. The battery management systems do detect a lot of issues, thermal and shorts but at some point I think government is going to force these to be on the outside of houses.
The right answer is LifePO4 for home storage, does not combust and has good enough density.
Agreed. I think that about ten years out, when solid state batteries are widely available, lithium-ion batteries bigger than laptop-sized will be prohibited.
Once we have solid state cells I really hope the entire industry moves over to them and we just have solid state, LFP and Sodium Ion, all nicely non combustable chemistries that offer different price, power and weight density trade offs.
Solid-state batteries will never be suitable for all applications, even if they should suffice for the most frequent of them.
Batteries with liquid electrolyte will always be able to provide greater power (i.e. greater current) within certain physical constraints. This should not matter for smartphones or laptops, but it should matter for many things with motors.
In a battery with a liquid electrolyte, the interfacial layer between the electrode and the electrolyte is fractal in shape, created by a carefully engineered chemical reaction between the electolyte and the electrode to maximize the surface area. You can't really do that with any solid battery chemistry we are currently studying.
I think the issue is overblown. Most users who need high power also benefit from high energy, and you can always run more batteries in parallel.
It's the common problem with almost anything in physics or chemistry.
The Good Stuff has some horrible flaw that makes it incredibly dangerous.
When we invented refrigerators first, they used ammonia as a refrigerant which was awesome at moving heat around. It's still used industrially but people die from ammonia leaks. Then they swapped it for freon, which was just about as good at moving heat around, but rotted holes in the ozone layer. So they got replaced with R-134 which wasn't as bad for the ozone layer (but still not great), slightly more toxic, and still quite nasty stuff to handle.
At present the best bet for refrigerants turns out to be good old propane, which if anything is a little too good at moving heat around (and your evaporator will freeze if you're not careful), reasonably non-toxic (don't breathe it in, but unlike ammonia a tiny amount in a room won't dissolve your lungs), and its only real downside is that it burns. People are worried about using C3 or C5 (pentane) refrigerant in cars, but the worst that would happen is you'd release about a deodorant can's worth of the stuff into something that's already on fire and contains maybe 70 litres of petrol. Your petrol tank is a bomb, made of a leaky plastic bucket full of explosive. The aircon having a cupful of LPG in it is not your problem in an accident.
Thus it is with batteries.
It turns out that one of the best kinds of batteries you can make in terms of longevity, power density, and stability is a couple of bits of lead in a bucket of sulphuric acid. They work great. They're in production today, and will probably be forever. Your car has at least one (mine has three, a massive one up front for starting the engine and a couple of smaller ones in the back for running things like the radios and inverter when I'm stopped).
However, lead compounds are pretty nasty, sulphuric acid is pretty nasty, they're heavy, they will stop working if you leave them discharged, and in general people would like something smaller, less corrosive, and less dependent on digging up vast areas of China to pull poisonous dust out of the ground.
So we have NiCads (oh dear, cadmium, one of the nastiest poisonous metals because it's poisonous all by itself - it doesn't need to be complexed to something organic to get in you), then NiMH (cheaper, non-toxic, and more-or-less a drop-in replacement for NiCads in any given application). Then we've got the various rechargeable lithium batteries which can do exciting things when damaged.
But for high power density, low cost, and and high current applications where you don't have to worry about carrying them or tipping them over, you're going to be stuck with lead in a bucket of acid for a while I suspect.
> They're in production today, and will probably be forever.
I suspect their days are numbered, because they have become _far_ more expensive to dispose of, and that's only going one direction.
> But for high power density, low cost, and and high current applications where you don't have to worry about carrying them or tipping them over, you're going to be stuck with lead in a bucket of acid for a while I suspect.
You'd think, but they _haven't_ seen a lot of use in, say, grid-scale applications.
> I suspect their days are numbered, because they have become _far_ more expensive to dispose of, and that's only going one direction.
They're insanely easy to recycle. You melt lead, you recast it into new plates. Sulphuric acid is very easy to make, and we need to make a lot of it as part of the process of making fertilisers.
> You'd think, but they _haven't_ seen a lot of use in, say, grid-scale applications.
Every telephone exchange you have ever dialled through is powered by massive lead-acid battery, with cells about the size of a decent microwave oven.
> You'd think, but they _haven't_ seen a lot of use in, say, grid-scale applications
Their power density is integer multiples worse than Li-Ion no matter what you look at. Not to mention numerous other problems. So it's not surprising at all.
> Their power density is integer multiples worse than Li-Ion no matter what you look at. Not to mention numerous other problems. So it's not surprising at all.
Yes, but you can use them in areas where you can't use Li-Ion.
Shameless plug: we're building a repairable e-bike battery where you can use your own cells at https://infinite-battery.com
We worked on a very sturdy casing, with some specific features to release pressure and limit the fire event propagating cell to cell, you can check it here https://www.youtube.com/watch?v=v0NXXfCA2CY
I'm confused why your value proposition is that you can replace individual cells but your website also says it's recommended to replace all cells at once. Isn't that the same as the current situation where we have to buy a new battery assembly rather than replace the failed cells?
> When an E-bike battery fails, 90% of the time, its just 1 or 2 cells that are dead inside or a single electronic component. But since traditional batteries are spot welded and glued, there is no chance to replace the faulty part and you need to replace the complete battery.The infinite battery is different. It uses a technology that makes it easy and safe to replace any parts, including lithium-ion cells. It doesn't require any specific tools nor knowledge. It takes less than 10 minutes.
> For safety and durability, it is recommended to change all cells at once.
You should definitely replace all cells together - a new cell will have a different capacity and could "charge" an adjacent older cell to rebalance, causing a fire (but a good BMS won't allow that - on the other hand you'll be limited by your weakest cells despite having put some new ones in)
For me the value proposition would be to avoid what happened with my previous ebike: after 3 years I wanted a new battery as the old one was on its last legs, and it wasn't produced anymore. Or what's happening with my current ebike: to avoid the same story with the battery, I am thinking of buying an extra one now while it's still produced, and it's outrageously expensive (550EUR for roughly 500Wh, which is about 7..10x the price of the cells if you are a careful buyer).
(You can fit a new battery to any bike with (sometimes lots of) extra work, but esp. my previous one had a weird solution where it slid into a rail above the rear wheel and it would have been a PITA to reengineer.)
So yeah if their thing works I'd consider a bike using it, on economical grounds mainly.
Exactly! That's precisely why we designed the battery, to let people be in control of their own stuff!
Our batteries have now be running for close to 3 years on shared mobility ebikes, so they are well-tested indeed! If you want more infos, send us an email at [email protected] :)
At 199EUR without the cells, I'm _almost_ tempted to go for it. It's a bit steep but the savings on the cells would already make the whole thing overall viable. If it had the ability to charge from USB-C as a contingency solution, it would be an impulse buy.
Indeed! We've been asked for the USB-C quite a bit so we might do that in a future version, but it increases the BOM price for our shared mobility fleet customers which are quite price sensitive!
Indeed it's 199 eur, but it's high-quality, certified, comes with a waterproof and fireproof casing, connected, with real-time safety alerts, and when you'll eventually need to change the cells, you'll only pay 50 eur to refill your battery!
Compared to that, an equivalent Bosch battery goes for 500 to 700 eur (for the same quality). We're even compatible with Bosch gen 2/3/4 (non-smart)
- you can indeed change the cells! When the industry matures, we might have a "second-life cell cycling" path where old cells are re-tested and matched so you could switch individual cells, but for now, as those "matched cells" aren't widely available we recommend you switch everything to new cells (this would cost an end-user about $50 rather than buying a new battery for $200/$300)
- our battery is also very high quality (passes all certifications, waterproof, fireproof, connected, with safety alerts)
- even if you need to change all the cells sometimes, getting back "pristine cells" rather than "damaged, welded and unwelded cells" will allow for multiple things: putting them in a second-life cycle for eg. energy storage batteries, and even better recycling (since you can get cells out of the casing, the recycling process is even more efficient)
- now the cells are perhaps 1/3rd the cost of a battery, so all things being equal, you'd rather be able to change all cells than throw in the trash the old battery
- we also have seen some batteries fail because of broken electronics, etc, which are just $30 to replace, and our battery makes it extremely simple to do so
Ahh, I get it now. Maybe you can improve the wording around this to make it less suggestive that your value proposition is I can change one cell when it fails. That's not safe. The value prop is I can change for a new set of cells cheaply when I get a failure in my current set.
You're going from when one cell fails, change the entire battery assembly, including any management electronics, case etc
To
When one cell fails, just get a fresh set of cells, at a fraction of the cost of a new battery assembly.
In the future, you also expect working cells to be circulated back into second-life use. Your casing makes this much more likely.
I payed 1$ in July 2024 to reserve a launch-day discount. I never received any emails from Gouach after the receipt. You moved from Kickstarter to you own website.
Are you actually shipping to costumers?
I was super excited back then about your product and company, but the rebrandings and lack of communication made me wary.
That’s pretty cool, but it took me quite a while on my phone to figure out what I need. Been doing e-bikes since 2007. Also, the little plus next to the shop was confusing to somebody that had a beer. I think your product is hot, thanks for making something that the world needs.
Ideally build it in away from your house, as others have said, but in terms of actual safety systems:
-get a high quality BMS from a reputable source, it should supports current limits and thermal probes
- configure current limits with as much overhead as possible, the less you drive them, the cooler they'll stay
- make sure you have sufficient thermal probes inside key points in the pack(s) and that they're configured in the BMS to cut draw
- add thermal fuses as well, knowing where to put these is important, too
- house the packs so to minimize fire risk and cascading issues, especially if space is not a concern
Looks like that case was resolved to the policyholders satisfaction, so not a good example at all. Besides that, the denial was because they were, in actuality, not in compliance with their policy, not because they did something stupid. It was a stupid denial because the violation was extremely in the “well, technically” category, and had nothing to do with the loss.
Okay, I suppose I asked for that, exposing my US-centric thoughts. I meant in the US :).
In the US, insurance covers stupidity. At least once -- your insurer may drop you after they pay out. As long as you don't have an exclusion in the contract covering a particular type of stupidity, and you are not committing fraud, you will be covered.
Also, I’ve always had a rider in my contracts that said the insurer waives their right to not pay if I’m at fault. I don’t know why this rider even exists but I always get it since it was first offered to me years ago.
Are you still talking about the battery starting a fire, and saying that it's my fault rather than the battery's fault? Because that's not an "indeed". I'm talking about non-battery fires.
If you're on the same page as me, and talking about non-battery fires... What makes it my fault?? Are you saying any possible fire is my fault? With the implication that insurance shouldn't pay out for any fires ever??
Small outbuilding. Concrete pad. Cinderblock walls. Sheet metal roof. Safe distance from anything important. Typical cost is $3000-$4000. Farms often have little buildings like this.
(There are pictures of such buildings online. Search is returning awful LLM-generated garbage landing pages, so I don't have a link.)
Throw it in a massive body of water is about as good as you can do until the energy is depleted. (Also, making a human perform the puncture to initiate a violent chemical reaction is WILD. Do better)
Distance, so a separate building far enough away from anything you want to keep that it won't carry over. Cabling underground but not in a duct. Space the cells a bit and ensure good airflow between them. A single runaway cell is how it usually starts and that in turn usually first shows up as increased internal resistance. Avoid mixing capacities, brands, different internal resistance values, cells that self-discharge, cells that have any sign of physical abuse or damage. (The guy in the video totally misses the internal resistance angle, as well as the self discharge which takes a long time to test and he already spent two months or more on his power bank.) Weld, do not solder your connections. Assemble cell groups first and then do QA on the cell groups as if they are larger capacity cells, and monitor them with a FLIR for any sign of cells misbehaving, especially under larger cell group charge/discharge currents. If a cell in the center is more than a few degrees warmer than those on the outside that's a serious concern.
Other prevention measures: strict inbound QA on the cells.
That's a lot of work, to the point that if you value your time you are better off buying a factory made pack of a reputable because they will almost certainly do a better job than you will on the safety aspect.
Getting Lithium-Ion packs right (especially larger ones) requires more up-front funds in terms of gear (especially testing gear for large volumes of cells is quite pricey) as well. The only reason I would do another (big) pack is if the form factor or capacity I want is not available at all.
The brief flash of that 'rechargeable powerbank' in the video has so much wrong with it that it isn't even funny and that's before looking inside the pack. All of those crossing wires, brrr. And those modules in the linked video don't look much better. Oh, and he's got one cell group in there with fewer cells (13:26) so that pack will unbalance immediately during charge or discharge. Effectively the whole pack has as much capacity as that one smaller cell group times the number of cell groups. The lack of integrated balancing wires is another puzzle for me, crossing balancing wires is a major headache when building larger packs, you want the very best grade of wiring for that with vibration resistant insulation and some kind of wire guide to ensure the wires can't move or cross. The whole BMS setup looks like an afterthought, rather than that it was designed in.
Oh, no interlock on the two separate breakers for the inverter (configured to work in island mode) and the house power. Wait until someone engages both. You need a transfer switch there, not two separate breakers.
His remark that it all looks 'super dodgy' and that 'I do not recommend anybody ever builds a pack like this' is an interesting one: if you are aware of all that, why do such a crap job in the first place? If you are going to go through that much work you might as well do a proper job.
Meanwhile, this is really just an ad for JLPCB. Running around the house and the workshop at everything working is a bit cringe, it is as if that's just padding to extend the video runtime.
