Uh oh. lost the magic smoke

madmax

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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
Yes, agree with you on that. But even so, there are cell fusing options that will work up to 15A. I don't work with anything near that. The Battery Hookup ones are good around 8 Max, with some heat build up and no air flow. But the ones Stucco was using is probably good to like 50A. Lol...
 

madmax

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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
No, its straight series- I just didnt know how many in series and parallel. Its at least 11P, and at least 7S, but it turns out it is way bigger than that!!!
 

BigGun

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I finally went back and Reread the OP -- You had those 18650s Parallel wired with a pack of SPIM08HP --You're lucky that's all that happened -- I wonder if when you drew enough amps the 18650 packs voltage sag allowed the SPIM08HP pack to back feed the 18650s
 

madmax

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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.
Save yourself some time, they have a couple of 48V units using the SPIM08's... get two and your ready to go~
 

BigGun

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Yes, agree with you on that. But even so, there are cell fusing options that will work up to 15A. I don't work with anything near that. The Battery Hookup ones are good around 8 Max, with some heat build up and no air flow. But the ones Stucco was using is probably good to like 50A. Lol...
I built some packs similar to your first video but with a wire that holds around 12 amps ---- One pack is a 3S7P of Tesla 21700 cells and another is a 4S6P with Samsung 20Rs -- they both have held up well -- I'm real conservative with the BMS s and with charging amps
 

madmax

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I finally went back and Reread the OP -- You had those 18650s Parallel wired with a pack of SPIM08HP --You're lucky that's all that happened -- I wonder if when you drew enough amps the 18650 packs voltage sag allowed the SPIM08HP pack to back feed the 18650s
I guess it pays to read (doh!).
Curious, in this config, wouldnt the BMS have limited the draw/charge from the 18650 pack?
 

BigGun

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I guess it pays to read (doh!).
Curious, in this config, wouldnt the BMS have limited the draw/charge from the 18650 pack?
Yep-- If he was using one --- a serious voltage sag would trigger a good BMS --- The 4S pack I mentioned, when the battery gets around 3.1v per cell the Sag on take off triggers the BMS
 

madmax

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Yep-- If he was using one --- a serious voltage sag would trigger a good BMS --- The 4S pack I mentioned, when the battery gets around 3.1v per cell the Sag on take off triggers the BMS
The wires would indicate at least something.. (balancer maybe... ). Unless the BMS was bypassed...
 

Substrate

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Some of you don't get it. Nearly NONE of these projects are engineered and built using NEW cells that were chosen to specifically meet the application. It is too cost-prohibitive.

Instead, most rely on un-vetted garbage. Or super-old random stock. As seen in the ops first pic. And then mash it all together with techniques gleened from manufacturers that use NEW stock and proper manufacturing techniques.

It is no different than the old days when an op would string together old used little 5ah agm's. All 100 in parallel with speaker wire.

Or the big boys stringing together a bunch of used car starter batteries found at the dump, and then asking us how to "improve" the system.

In other words, by starting out on the wrong foot, there is NOTHING to learn. Other than how to play with trash. And put ridiculous band-aids on trash, fooling yourself that you are learning.

Unless you start out with brand new cells, chosen specifically for the application at hand, all of this is pseudo-science, aka "milking the trash" for all it's worth.
 

Substrate

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If you want to follow the thread topic, and "Learn From My Mistake" then this is it:

The mistake is *starting out* with cells with unknown history, age, use or prior abuse, and just slapped together hoping that a "bms band-aid" will turn this collection into gold.

NOBODY (ok, maybe only 0.1%) specifically chooses and engineers these types of systems with NEW cells, and follows good manufacturing techniques. Instead, they spend money on tack-welders and soldering.

Heh, if Will found Sol-Ark's simply tack-welded haphazardly and soldered, he'd throw a fit! So should you.

Unfortunately, by starting out on the wrong foot with trash, any scientific or electrical engineering discussions about it, are now pseudo-science. At best, bordering on unsafe alchemy.
 

Stucco

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Yeah, it definitely was some shite cells flaming out. I only was using 1 pack at a time. Definitely wasn't going to parallel these 2 types together.

The motor I am using goes from 64 to 120v, 84 volts is kind of that sweet middle spot. The vendor said 96 volt is their recommended high point to really get it going.

I am trying to keep as much of the original frame in place. If I do this again I am probably going to build my own frame with more of a long design so I can put some really big watts behind it. Think Akira style bike.
 

BigGun

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Some of you don't get it. Nearly NONE of these projects are engineered and built using NEW cells that were chosen to specifically meet the application. It is too cost-prohibitive.

Instead, most rely on un-vetted garbage. Or super-old random stock. As seen in the ops first pic. And then mash it all together with techniques gleened from manufacturers that use NEW stock and proper manufacturing techniques.

It is no different than the old days when an op would string together old used little 5ah agm's. All 100 in parallel with speaker wire.

Or the big boys stringing together a bunch of used car starter batteries found at the dump, and then asking us how to "improve" the system.

In other words, by starting out on the wrong foot, there is NOTHING to learn. Other than how to play with trash. And put ridiculous band-aids on trash, fooling yourself that you are learning.

Unless you start out with brand new cells, chosen specifically for the application at hand, all of this is pseudo-science, aka "milking the trash" for all it's worth.
Yes your High Almighty -- Every one bow the master has spoken -- You have no idea the work and the testing of cells I put into building a pack -- Yes I agree there's a lot of shady stuff going on with all this stuff - From people not knowing what a Fuse is , to people buying crappy cells they trust are Grade A because some one across the water told them so -- But I can tell you one thing, It's not me. I'm not the smartest or have the most experience with all this stuff, but I see mistakes and bad practices from even the most revered members on this site
 

madmax

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Yes your High Almighty -- Every one bow the master has spoken -- You have no idea the work and the testing of cells I put into building a pack -- Yes I agree there's a lot of shady stuff going on with all this stuff - From people not knowing what a Fuse is , to people buying crappy cells they trust are Grade A because some one across the water told them so -- But I can tell you one thing, It's not me. I'm not the smartest or have the most experience with all this stuff, but I see mistakes and bad practices from even the most revered members on this site
Real question here; if you find a cell, even if its 10 years old, but you do a capacity cycle test on it, and it tests within 90% of its original published spec, and you build your pack to within those acceptable tolerances... how is this bad? Yes, there might be calendar aging issues later on, but these cells can still provide years of service. At least that what I've always thought...
 

Substrate

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Please understand this is not personal. And I totally understand the desire and motivation.

Unfortunately, diy'ers at this level are often the target of scammers trying to sell / discard questionable material - either by direct product sales or marketing to "look what I can do" like and subscribe videos.

Lets rule out the alchemy they don't want you to know: Even *IF* you pull out your Opus BT-3100 or similar (I have one) and measure for capacity and internal resistance (usually ballpark flaky), what you will NEVER know with used 2nd hand cells, or very very old stock, is the condition of the SEI layer from prior use/abuse/storage conditions.

THIS, despite all precautions taken as a master tack-welder or builder is part of the reason that seemingly ok engineering bursts into flames. There is no measuring tool available to the public that can determine things like this.

Hence the recommendation to use NEW cells, which often puts the project well beyond any normal affordability. Nevermind the underlying construction infrastructure considerations.
 

BigGun

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My thought is -- How old are those Ryobi packs you buy at HD for new -- no one knows --- All you can do even when you buy new cells is check them to the best of your ability -- I build high end flashlights and I'm amazed at what people who use them do -- they have no idea how to use them or know when problems occur -- you buy cells from a vendor who's reputable, but how long has he these cells in stock and up the supply chain. From my experience Sony Samsung Panasonic cells seem to be the best made
 

Substrate

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Well, for one thing, be SURE to be part of the CandlePowerForum community - particularly in this thread:


Pay special attention to op HKJ, his reviews, testing methadology, and gear. The material applies not only to flashlights, but nearly any application, especially for a diy'er which consists of putting the common non-lfp cylindrical cells together. It goes into far more detail than what is found here. You'll also find good distributors. In most cases you will $$pay , so that tends to end some large multi-cell projects right from the start.

So not my first rodeo when I make comments here. :)

In the early days, these guys were regularly hurting themselves, so they got attuned to what it takes to do projects safely. Unfortunately, this safety concern tends to not spill over into the ebike/power wall crowd.
 
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BigGun

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BLF --- but you're right HKJ does some serious testing --- Most people on BLF check his reviews before making a move
 

madmax

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Nobody really knows whether new cells have defects either. It isn't without failure rates, in fact, they can often be higher than in used cells. (Just look at the recalls/warranty claims). Heck, How long is the wait on the Bolt for a new battery pack?

Obviously new cells theoretically do not have calendar aging issues. Used cells may have been abused- depending. Cells from backup modems generally have not been abused. Cells from used scooter packs and even tool packs can be heavily abused. If all new cells are good cells, and tool batteries have many cells, there shouldn't be a reason why one cell in many cells die, even on packs that are less than a year old.

If its mission critical, go with new cells, and test them at least more than once before putting them in the field. I am often amazed of the design and testing of equipment that went into Voyager 1 and 2. One of them just fired its rockets after being dormant for 30 years in space. I can't even start my lawn mower after a season.
 

BigGun

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The first time I ever heard some one say you can revive low 18650 Li-ion cells, I'm like you're kidding me right. Below 2.6 basically garbage where I come from -- I really don't like below 2.80 -- then the phrase Heaters if you try to charge them to 4.2v ,yeah because they're wore out and if you try to full charge them they'll cook for hours
 
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