Uh oh. lost the magic smoke

Stucco

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So finally got the electric cycle to a position where I could test it out.

Low "gear" worked great, slow wind up to about 30 mph. Flipped it to high and gunned it. Power cut out.

I was thinking I was pulling too many amps through my transfer switch between my 2 batteries, so I removed it.

Hooked up the 18650 pack and took it for a spin. Cut out again. So I looked down and saw flames shooting from my 18650 pack.

20220507_124344.jpg

So these are not going back into this build. I'm just going to double up the SPIM08HP cells since they can pull more amps and have a much better connectivity method.
 

A.Justice

Swears he didn't start that fire.
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Glad you are okay, those 18650's can really shoot some fire. Luckily the other cells didn't vent.

I have an e-scooter that I'm building a battery for, I had considered using 18650's, but will probably end up going with the SPIM's or similar. I have some "small cell" packs, but with my skill level, I just don't trust my solder joints for high current.

How long did it take you to spot-weld that pack?
 

Smokin

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Rubbish Cells do it everytime. You need industrial grade new cells like what comes in cordless drill packs if your going to MadMax overload your battery. Or just get a Sur Ron
 

BigGun

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You should build your pack with all the same Brand Cells for a high amp draw -- Ebike/ Scooter high drain cells only--- good to know your total amp draw per cell and Fuse each cell individually

The only LifePo4 cell I know of in small form factor is the A123 -- they put out some amps -- I have a temp setup for a 36v / 1000w scooter using some NEC factory made 12v batteries in series --- At startup it draws 34amps
 

Substrate

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Ah, the perennial favorite way to play with trash unsafely - scooters and diy powerwalls.

Used cells, diy tack or solder welds and shade-tree so-called fusing. Skilled garbage-men pushing trash and total violations of safety into the "diy marketing demographic". Either by direct-sales of componentry, or web-pages and videos to like and subscribe to.

Nothing learned. Unsafe to both you and others. Either by direct consequences, or possibly later by those filing civil lawsuits when god-forbid, something happens out of your control.

Oh well, it never stops. Unfortunately, it associates DIY with kids playing with trash, which is sad.
 

A.Justice

Swears he didn't start that fire.
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At least we know that the cell-level nickel "fusing" works, and in the defense of cylindrical cells, there doesn't appear to be a catastrophic failure of multiple cells in a chain. That could have been way worse.
 

Substrate

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Yeah, I'm being harsh not on a personal level, but just a professional / legal level.

For one, if the house burnt down, would the insurance company who wants to deny the claim, be persuaded otherwise if it could be shown "he used thin-wires as a self-fusing agent"?

All I'm saying is that there is nothing to learn here about safety, but a demonstration of a dumpster-fire project gone wrong.

To be fair, this happened in my early EV days too, but on a different scale.

After a 300-reply thread about what could have gone wrong when his diy-EV went up in smoke, it was finally revealed that instead of using bus-bars on his calb prismatics, the guy was using unistrut! And they were all connected together with galvanized hardware from the home-n-garden section at Home Depot. Inside a large tupperware container.
 

Substrate

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That was part of my description. It's just called staying one step ahead, rather than looking solely at the initial appearance.

An example would be using 12v connectors that are only soldered, and not crimped. (different thread, this is only used as example)

Oh sure, they get warm, but not hot enough to melt solder. Until 2 years later when oxidation is such that the resistance rises enough to do so under heavy current demand. And now with your connector and cable hanging on the wall over your gear, the solder melts and splashes down on the controller circuitry. Cable weight pull right out from the connector, and the positive now fall down to a ground connection, direct short - you get the idea.

Just stay one step ahead - no need to go bananas with ridiculous what-if.

Still - like in the past - none of this means anything if you start out on the wrong foot from a learning standpoint. Plenty of EV'ers sent a lot of us on wild goose chases simply because they tended not to reveal their infrastructure, or that they were using 2nd-hand cells with no known prior history of abuse and were looking for a magic bullet to explain away problems, rather than have the finger pointed to their use of unsafe trash right up front.
 

BigGun

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Now I can understand where you're coming from -- I was raised around construction sites (residential ) and made it my career--- The things I see people do on jobs these days and what's shown in these TV shows is downright scary to me -- I'd like to think I have a 6th sense type of mind when it comes to safety -- But you can't always see all the dangers, Just try to be as best prepared as possible
And Learn From Your Mistakes -- :cautious:
 

madmax

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At least we know that the cell-level nickel "fusing" works, and in the defense of cylindrical cells, there doesn't appear to be a catastrophic failure of multiple cells in a chain. That could have been way worse.
That isn't cell level fusing, not in the least bit. Ok I take it back it has a minor amount of "fusing".. if you consider only fusing on one side and not the other.
3P_56b9ed6c-4c68-4099-88d6-fb9172b103b0_1080x.jpg
 
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madmax

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Curious, is that a 36v or 48v setup? What's the bms you got on there?

There's nothing wrong with using recycled cells, obviously bad cells and bad designs can cause problems. Look at all those hoverboard fires. Technology has certainly gotten better as you see less and less of those problems (maybe it was the switch to lfp).
I use a 13s18p, on a "500"w motor. I did do cell level fusing.

The problem I see (as compared to what I do, maybe I'm wrong) is that your nickel connectors are way too beefy. Your battery need to basically be on fire for those to blow.
Let's assume you built a 13s pack... But you only used a single cell for one of them while every other row of cell has 10 cells. The demand on that single cell would be legendary. It has to disconnect from the pack or blow up. Cell level means each cell has to be fused to a row bus.
 

BigGun

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Depends on what type of pack your building --- If you're using high drain cells ( for instance Sony VTC6 ) in a 10S6P battery pack to run a scooter.
You have to have a fuse that will hold up to the amp draw you're needing --- So if you use that thin wire you'll blow all the cell fuses on the first start up-- If you use all VTC6 cells in a 6P configuration and need 30-35 amps for start up it's perfectly fine --- But they need to be tested and resistance matched -- his problem was he had cells that looked like laptop pulls , maybe old heaters who knows
I get a kick out of people selling and using cells they call heaters -- they are garbage
 

Stucco

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It was an S21 JBD BMS for 84 volts.

The SPIM80 will be much better in this config. They will have solid aluminum block busbars instead of Nickel strips. Going from 21S1P to 21S2P for more range.

I will keep the 18650s for repacking tool batteries, or creating 12v battery charger boxes.
 

BigGun

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1P -- I'm surprised the bike even took off at all ---- How is that pack built on the other side --Looks like a lot of Parallel cells to me
 
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