Grin’s perspective of Ebike fires

Honestly these first gen sodium ions we can buy kind of suck, close to as energy dense than headways lifepo4 cells..

Here's a 36v 12ah headways pack from 2011, lol. Today you would be expect this to be a 36v 40ah pack..

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The thing about sodium ions is that they have the potential to become nearly as dense as regular lithium, right now the record is something like 200whrs/kg but you can only buy this 50-100whrs/kg stuff today.
 
The thing about sodium ions is that they have the potential to become nearly as dense as regular lithium, right now the record is something like 200whrs/kg but you can only buy this 50-100whrs/kg stuff today.
Of course battery pack weight does matter for many ebikers, but not for me - I'd be quite happy with a safer 10kg-15kg battery on the pannier rack, easy for my bike to drag about.
 
Pretty much all of us have lithium batteries, and a lot of us build our own packs. This discussion begs the question: how many of us have had a runaway battery fire? I'm not asking about an electrical fire in a battery, but a thermal runaway.
 
That battery got maybe 20 miles on it before i got sick of the bike being wobbled by that pendulum-ing of that big weight in a not so ideal place. I would constantly have to counter-steer around it. It got annoying fast.

I went to buying really big framed hardtails and stuffing them to the brim with 150whrs/kg RC Lipo to just barely get the kind of range i wanted at high power. No more weird handling problem and generally the bikes handled more like regular ones, just heavier.

If you want to build a monster pack, consider going this way, it's a great place to mount a battery!

30s10Ah.jpg
 
Pretty much all of us have lithium batteries, and a lot of us build our own packs. This discussion begs the question: how many of us have had a runaway battery fire? I'm not asking about an electrical fire in a battery, but a thermal runaway.
I had an entire lithium ion pack catch fire once. It was an old pack with the cells super glued together and I was trying to pry off a p-group to change the voltage, though.

Anyone know if we can solder instead of spot weld on sodium ion? I'd so love to ditch the whole, thin plates of copper nickel sandwich thing lithium ion battery building requires just to cater to weak DIY spot welders...
 
If you want to build a monster pack, consider going this way, it's a great place to mount a battery!
Woah, that looks like you've robbed a bank which trades in lithium-ion batteries. Are roads in the USA optically flat? Don't those batteries get jostled and bounced around in the bag when you're travelling at high speed? If energy desnity increases substantially, you can use one battery pack, and start a lucrative second career running coke across the Nevada border. The CofG of my bike is low, handling isn't affected much by heavy weight on the pannier rack. With sodium-ion cells, I'd be more inclined to balance the pannier rack battery with an additional one situated over the fold like this guy...


...and run them in parallel; presumably safer to do than with lithium-ion. Plus two bottle batteries strapped under each chainstay, plus two more on each prong of the front fork (no suspension on the Helios), if I needed much more range. What's the worst that could happen? I look forward to the lack of thermal runaway leading me to experiment foolishly, probably with knitting needle welders.
 
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I had an entire lithium ion pack catch fire once. It was an old pack with the cells super glued together and I was trying to pry off a p-group to change the voltage, though.
I can guess, but for the newbies who are learning. Would you say that the fire was caused by mechanical mishandling, rather than from charging/discharging? Did something happen to the group you were working on, that spread to the rest of the pack? Just want to get a picture of the process for learning purposes.
Anyone know if we can solder instead of spot weld on sodium ion? I'd so love to ditch the whole, thin plates of copper nickel sandwich thing lithium ion battery building requires just to cater to weak DIY spot welders...
Presumably the cans (if we're talking about cylindrical cells) are nickel or nickel alloy, meaning it is possible to solder them. Therefore, in the same way that you're not "supposed" to solder lithium ion cells, you can still do it, and it's entirely possible for it to be done quickly, safely, and effectively... if you're practiced, skilled, and experienced. Which is to say, not likely. One of the main reasons that we try to steer DIYers towards spot welding, despite the lack of sufficiently powerful DIY spot welders to make good connections, is because it tends to decrease the amount of heat transferred to the cell, relative to soldering. This would decrease the chances of both exciting/dangerous thermal events, as well as decrease the odds of damage to the capacity of the cell you're working with.

(I do realize that this is known to most readers, but I want to respond thoroughly for the newbies who happen to come across the thread wanting to learning about DIY battery safety).

I would suppose what you're asking is, does the higher heat transfer risk of soldering vs spot welding effect the safety or chemistry of sodium ion cells, relative to lithium ion? In terms of safety, we already know that LiFePO4, on average, does tend to have a higher tolerance for temperatures as compared to lithium ion. Likely due to its more stable chemistry. So it would be fair to assume that sodium ion will also be more tolerant to heat from soldering, in terms of safety. Though it's important to remember that "safe" is relative, and it's still possible to have thermal events with sodium ion:

In terms of how heat affects capacity, only time will tell, as these are still fairly new and they haven't run the same gauntlet of experiences. I plan on googling it every couple of months to see what's new. Also, we have a good thread started on it here, if others come across good info on it.
 
My triangle case had nice padding in it, i added padding between the batteries, and battery motion was very minimal, and batteries rubbing on / hitting each other was reduced to nothing.

2 52v x 20ah modern batteries would fit in that same size triangle. 2kwhr club is good times.. :)
 
I can guess, but for the newbies who are learning. Would you say that the fire was caused by mechanical mishandling, rather than from charging/discharging? Did something happen to the group you were working on, that spread to the rest of the pack? Just want to get a picture of the process for learning purposes.

Presumably the cans (if we're talking about cylindrical cells) are nickel or nickel alloy, meaning it is possible to solder them. Therefore, in the same way that you're not "supposed" to solder lithium ion cells, you can still do it, and it's entirely possible for it to be done quickly, safely, and effectively... if you're practiced, skilled, and experienced. Which is to say, not likely. One of the main reasons that we try to steer DIYers towards spot welding, despite the lack of sufficiently powerful DIY spot welders to make good connections, is because it tends to decrease the amount of heat transferred to the cell, relative to soldering. This would decrease the chances of both exciting/dangerous thermal events, as well as decrease the odds of damage to the capacity of the cell you're working with.

(I do realize that this is known to most readers, but I want to respond thoroughly for the newbies who happen to come across the thread wanting to learning about DIY battery safety).

I would suppose what you're asking is, does the higher heat transfer risk of soldering vs spot welding effect the safety or chemistry of sodium ion cells, relative to lithium ion? In terms of safety, we already know that LiFePO4, on average, does tend to have a higher tolerance for temperatures as compared to lithium ion. Likely due to its more stable chemistry. So it would be fair to assume that sodium ion will also be more tolerant to heat from soldering, in terms of safety. Though it's important to remember that "safe" is relative, and it's still possible to have thermal events with sodium ion:

In terms of how heat affects capacity, only time will tell, as these are still fairly new and they haven't run the same gauntlet of experiences. I plan on googling it every couple of months to see what's new. Also, we have a good thread started on it here, if others come across good info on it.
Well, very comforting to know they don't catch fire. They just explode.
 
Well, very comforting to know they don't catch fire. They just explode.
You're not seeing the benefits - if the battery is mounted on the rear rack, the explosion runaway effect could add thrust increasing speed legally. Exploding mid-mounted sodium-ion batteries would of course boost height, providing much needed cyclist visibility to other vehicles. That much explosive force inside a typical downtube battery case will set off adjacent cells, popping the case. Perhaps cases could retain the modicum of waterproofing they have now, with the addition of large flat fast pressure valves of some kind? To be exploded off more predictably, like the cell caps. Ebikes might be designed situating sodium-ion batteries as far away from the rider as possible, or direct the force of the explosion away from the rider's body, kindof like shaped charges the SAS use in movies.

Oh well, at least fires will be much easier to extinguish. Sodium-ion battery storage facilities won't burn for weeks or months, there will be very large sudden craters instead.
 
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NHTSA recently did a series of tests on electric vehicles to stress the BMS and also a series of tests where a single cell in each battery pack was forced into thermal runaway to see if the thermal runaway would propagate through the battery pack. Reports are published here: Regulations.gov
 
Well that was ummmm....interesting! This is certainly a sensible option for removable ebike batteries. Most of us here aren't using those though.

Cheers
I daresay while charging, there will be some temperature change very near wherever the battery is located on the bike/scooter - I really didn't think temperature change would be detectable with the probe situated on the plastic battery case, but it is. Worth having a go. The STC-1000, polystyrene block, and velcro strap don't cost much.


STC-1000.jpg
 
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are there any rules saying what is in a battery pack
Li or Li-ion covers many types I would like full true chemistry
is that needed or will china just lie anyway ?
I know
will a discharged battery burn [of the burning types]
or just burn a bit less ?
what about the exploding sodium bang if discharged or just less or what ?

is there a list of pack not cell makers who only use NON BURNING CELLS
I know some cell makers are better mostly japan based corp vs china
but how to tell what is inside and if it BURNS OR NOT
 
but how to tell what is inside and if it BURNS OR NOT

You can look up cell safety tests for practically any cell, either done by the manufacturer, or someone on here, or on youtube has probably tested the cell.

You should think of safety in terms of what kind of chemistry the battery is based on. Lifepo4 and lithium titanate ( LTO ) are known to be really safe. Japanese/Korean cells are fairly safe. RC Lipos ( li-co ) would be on the opposite end of the spectrum as the least safe.

To make a blanket statement, if oyu want safe, you generally want to stay away from Chinese cells, not sure how well big makers like BYD/CATL fare, they may be better.
 
MANY OF US BUY PACKS

cell data is eazy to search sure
esp for big corps

but what cell is in a pack is not near as eazy
vs running changes switch suppliers new improved BS
vs mis or dis info counterfit bad batch ect
or does the ad guy even care
know or want to know or lie about the sealed pack
 
It’s pretty easy to eliminate the potentially bad battery packs from the ones that are potentially good. On the first cut, look at the sellers description. If the specs are ridiculous, claiming huge Ah or current capability, no go. If they mix up specs, like A vs Ah, etc., they are a No. If they don’t list the cell brand and type in the description, they are a No*. If they make it past the first checks, then they are worthy of further investigation. It will probably be a short list.
*if they list the brand, but not model, you may be able to guess based on other pack specs, but should be clarified before buying.​
Pull up the manufacturer's spec sheet for the cells the description claims to be using. Use math to check the information listed in their ad against what you can calculate using independent (manufacturer) data (e.g. number of parallel groups, times the stored mAh equals the stated pack Ah, etc.).
There’s a lot you can check without having to ask the seller a question, so your remaining questions could be on things that may not typically in the descriptions, but important to your decision making (does the BMS have balancing; is there a fuse inside, etc.).
 
Well, the main thing I learned about battery fires, is that it goes up crazy fast, and its a big ass fire when enough cells are involved. In my case, after 30 pounds of charging 18650 cells lit up my garage, the fire really got big after the motorcycle and car containing 20 gallons of gas also caught fire. The flames coming out my garage door were 50 feet tall by then. This took just about 3 min.

The bike, once it went up, took very little time to melt the plastic gas tank of the scooter parked inches away, after that, same thing happened to the car. The only thing left of the scooter was a puddle of aluminum.
 
Well, the main thing I learned about battery fires, is that it goes up crazy fast, and its a big ass fire when enough cells are involved. In my case, after 30 pounds of charging 18650 cells lit up my garage, the fire really got big after the motorcycle and car containing 20 gallons of gas also caught fire. The flames coming out my garage door were 50 feet tall by then. This took just about 3 min.

The bike, once it went up, took very little time to melt the plastic gas tank of the scooter parked inches away, after that, same thing happened to the car. The only thing left of the scooter was a puddle of aluminum.

Can you be more specific please and provide as much information as possible? Link to battery, was a fast charger used, did you modify battery in any way etc
 
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