If the cell wrappers still have contact with each other, that’s enough.
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The cells are fully potted not just the shrink. And as I say these cells … I can’t get them to go to flames no matter what I do and I do. I feel safer with this than any kind of ion battery.
Lately been thinking with ion cells, if they were to short, a really high power cell is a boon as it will blow away the short hopefully before it can send cells into runaway or cause a fire
Ok but death by fire isn’t the only risk here, even pretending that LFP can’t catch fire it’s still very very bad if that pack shorts out. The device stops working, potentially with a rider on top, the whole assembly needs a lot of work to even assess what happened. Not burning a house down isn’t the bar needed for a successful build
Also physical abuse isn’t the only damage you can do to a cell, if a p group is shorted out but the pack is still drawing current you’re driving a current backwards through it and they do not like that
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I’ve shorted the battery a couple times to see. There’s not much left to cause a short as the wires were blown off. I’ve built ion batteries and had them short and scared me badly with popping valves but this chemistry and also potted seems the safest thing possible. I get that you guys are looking for weaknesses and it’s appreciated but I’ve done a lot of testing and ended up destroying the battery in the end just to see what would happen.
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Ok, so I build illuminated signs at my day job. Our 24V PSUs have short circuit, over temp, ground fault protection, etc. The frames are grounded, the sign materials are self extinguishing, all the bells and whistles. If you get a short, the worst case scenario is that some magic smoke tarnishes the sign and the lights go out. I STILL wouldn’t use that as an excuse to leave voltages separated by nothing but 0.3mm of PVC or use conductive glue for critical wires.
I think you’ve shown that the risk of catastrophic personal injury is relatively low, sure. But this rubs me the wrong way because the strategy seems to be finding a maximum acceptable risk instead of a minimum possible risk.
I ride experimental vehicles at unreasonable speeds because I’m wearing as much body armor as I can buy and I seek out empty roadways, and then my brain rewards me with the happy zoom zoom chemicals. What are you getting out of this pack design, reduced build time? Not worth it IMO
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I don’t know if that’s a rhetorical question but I don’t see a risk of anything rubbing otherwise I’d be separating p-groups with something
That is not the same thing at all lol
It takes about 10 seconds to solder on a balance wire, or less, even. The heat doesn’t even reach the internals of the cell if you are doing it correctly.
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I guess next one I’ll solder. If there were a conducive instant glue though I think it would work fine
Doesn’t exist AFAIK. There are “conductive” epoxies (silver, nickel, or carbon loaded) but their resistance is verrrrry high compared to a soldered connection and I would hesitate to pass even balancing current through them. This is because the high resistance fools the BMS due to the voltage drop through the epoxy, extending the time needed to balance the pack.
To be fair, it you had a very good mechanical connection between the balancing lead and the nickel then I guess the epoxy could be used to just affix the lead in place. Soldering is just so easy though and is a proven method.
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Couldnt have said it better myself.
@hummieee I’m not going to tell you that you should not be building batteries this way (though I dont think you should) and I’m not going to tell you that your batteries are 100% guaranteed to fail (since you clearly demonstrate “it works for me”). However, when you post the battery building techniques that you have (and then defend them) I am worried that someone in the future might read that and think it’s ok to follow your example for their esk8 battery. I am, therefore, going to tell anyone who is reading this in the future:
Do not follow this example. This is not a safe way to build a battery.
People come to this thread to learn how to build esk8 batteries. Esk8 batteries have a much higher safety standard than other applications because of the intense vibrations, shocks, and general abuse they are subjected to when strapped to the underside of a skateboard. Do not glue your balance wires to the cells. Always use fish paper between p-groups, and fishpaper rings around the positive cell terminals. Potting your battery is not a replacement for these other safety features.
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Also, use case on a bike is pretty different to an esk8
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I too don’t build skate batteries like this. This is for a bike. Potted. Lifepo4. And using 50miliamp balancers.
I see no voltage drop at all with the glued on balancers.
Everyone wants to be the safety police but in reality I trust this battery more than all the ion cell packs made. I’ve seen ion fires in diy stuff where they don’t even know what happened. There’s also faulty bms and no fault of the battery or the maker. These cells straight up don’t turn into flames unless u puncture them and even then not as bad as ion from what I’ve seen
If ur using lifepo4 you’re inherently safer period in my mind no matter what safety measures taken. They’re all preventative… while with lifepo4 there isn’t the risk to begin with
@Battery_Mooch have you seen those cheap cell holders snap into PCBs before? somehow never seen that.
Have you tried welding the balance wires on instead? I guess that could be difficult or introduce a failure point with loose strands + wire is copper so only Kweld with bigbatt/caps would manage this.
Wondered about this product before
I guess you could DIY this if you could get pure cemented silver(from metal refining) & mix with suitable epoxy
Yes, thanks. Verrrrry interesting concept!
I’ve been following the channel and commented on the video. 
I haven’t seen the full setup used hard yet though so their testing will be interesting to see.
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If anyone was willing to send a syringe kit of this stuff I’d be happy to do some tests on it…electrical resistance, heating, how it fails from overcurrent, adhesion to nickel, impact and moisture resistance, etc.
I don’t think using it is a good idea (too many unknowns and soldering is an established method) but I am a firm believer in having all the data and making an educated decision on the risks involved.
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