diy solar

diy solar

Uh oh. lost the magic smoke

@curiouscarbon - you hit the nail on the head.

There is no way to determine the SEI layer condition with cells of unknown past history. And if in fact they claim to be new, that they are not counterfeit. One can get counterfeit A123 wrappers to go over / replace old ones pretty easily. Or the more common one of sitting in a hot warehouse for a few years, and then zapped just a little bit before sending them out.

Even vapers get ripped off at times.

To be sure, marketers targeting us who may read these threads, will now supply either bogus x-ray imaging photos! :)

Ironically, an additional profit can be made by selling all the paraphenalia that goes with it. Tack welders, nickel strips, soldering guns - and now x-ray machines (why didn't I think of that!), special holders. That's some good $$$ to be made. Get a buddy to make some videos with links to our "product".

The problem of supporting band-aids (no matter how scientifically well it is discussed) over the initial problem of trash, is that we are sending mixed messages to manufacturers that it is ok to do so - despite us trying to hold them accountable to the highest standards of quality in other battery systems.
 
Please - stop trying to justify the use of band-aids for trash.

Presumably this forum is to "learn" from, and not just a be a dumping ground for pics of stuff that "blew up real good".

Why Yes, As a matter of fact, that is exactly what this "Up in smoke... learn from my mistake!" subsection is for.
 
we are up in smoke, pack your med kit!

due to topic of motive application and eschewing types of cells, i will share that the headway 38120HP 8Ah cell, if it can be sourced genuinely and new, is one option for a potentially good time.

not paid to say this, no association or whatever. the blue jacket 17Ah are decent too.

assembly effort becoming like building a huge pyramid with 10+ parallel cells and 8+ serial cells, i never could bring myself to face.

admittedly my engineering paranoid has driven me to designs where every individual cell is monitored by a BMS.

because of the whole unknown history of some cells, and different specs, when paralleled, issues are more difficult to discern by voltage monitoring alone.

used high amp rated cells (like the 38120HP 8Ah headway cell) can work GREAT!

stored in a warehouse at high temperature for a long time, overvolted, undervolted, and not stated of course can result in unexpected catastrophic failure. the calendar aging has been happening the entire time since manufacture, etc..

so my "2cent" is to find high amp rated cells that result in less than 2 cells in parallel ?️;) (one cell per BMS connection)

headway, frey, A123 are three manufacturers (i think they are manufacturers..) that i believe to make high quality cells.

new cells are BEST when budget allows.
 
this motive application build was one of a few that really "drove" it home for me that not all cells are the same. not associated. wish i was, because oh my gosh i want to drive it... :oops:


 
There is no way to determine the SEI layer condition with cells of unknown past history.
me wish every cell had a small thermometer and few megabyte data log to automatically log decades of cell voltage, temperature, with automatic stopping when low voltage to prevent damage. like even once every 60 seconds can do wonders in my imagination of diagnostic ease.

of course, then the game becomes, providing a false history of a cell being treated well. but for cells that are under semi-continuous physical management, the history log can be more trustworthy.
 
I have a fuse on the controller itself, specifically in case the pack went tits up.

I have 2 4 port opus, and 2 4 port dedicated chargers for the 18650. I spent months cycling batteries through charging and discharging and disposing of any that didn't make the cut.

You are 100% right that these were not the right cells for this job. I am retiring the survivors for other lower amp projects, and sticking with the spim packs for the cycle.

The spim, while larger, do have better draw, and are much easier to assemble with beefy bus bars for handling the load.

For those I am planning on using aluminum stock bolted to the tops and bottoms with a compression washer to guarantee tight connection to the mounting plate.
 
And a Fire Extinguisher mounted on the handle bars -- JK :oops:
I would discard any cells that look like they were close to the heat
 
I have 2 4 port opus, and 2 4 port dedicated chargers for the 18650. I spent months cycling batteries through charging and discharging and disposing of any that didn't make the cut.
This is the problem. There is a 3rd factor which you simply can't measure, that is, the SEI layer degradation.

It works like this - and frustrated many tool owners initially. They got full performance out of their tools for weeks, and then suddenly the next day, NADA. Total shutdown.

Much of this was due to malfunctioning chargers, but in some cases, like in Arizona or other high-heat locations in the garage too, the SEI layer was quickly growing to such an extent that the area that was able to do the inter-calation was now the size of a pinhole!

That last charge / heat closed up the pinhole now completely clogged and the cell. But how could this be? These were like NEW for like a month?!?! And only a few cycles on them!! SEI layer shutdown with plenty of capacity left! But now you can't get to it.

A common criticism of using lithium powered tools was that they were subject to "sudden death", so better stick to nickel-metal-hydride because they gave you some indication of their poor health. The "sudden death" was due to not understanding how the SEI layer degrades with the common storage practices of leaving them in hot sheds.

So even with used cells that seem to pass capacity and internal resistance checks are no guarantee that the SEI layer isn't on the brink of shutdown.

I guess at this stage if there was *any* advice to learn from from used cells is that if you are going to use them, make sure they are ALL from the same manufacturer / counterfeiter, same batch etc. Even though they may not be optimal, at least there's a chance their SEI layers are all in the same relative state of degradation.
 
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Guys - I'm not trying to be harsh.

Knowing these things is what makes the difference between winning at the track in your drag-ev, and your e-bike going up in smoke outside in the bike-rack at Taco Bell.

I've been watching these guys in the White Zombie for decades, back when they were Plasma-Boy racing (good story to learn from) with pure-lead agm's.


The don't put random collections of cells in the motive-power application. Because they know what happens if you do!
 
me wish every cell had a small thermometer and few megabyte data log to automatically log decades of cell voltage, temperature, with automatic stopping when low voltage to prevent damage. like even once every 60 seconds can do wonders in my imagination of diagnostic ease.

of course, then the game becomes, providing a false history of a cell being treated well. but for cells that are under semi-continuous physical management, the history log can be more trustworthy.
Aint that the promise of block chain technology?
 
Guys - I'm not trying to be harsh.

Knowing these things is what makes the difference between winning at the track in your drag-ev, and your e-bike going up in smoke outside in the bike-rack at Taco Bell.

I've been watching these guys in the White Zombie for decades, back when they were Plasma-Boy racing (good story to learn from) with pure-lead agm's.


The don't put random collections of cells in the motive-power application. Because they know what happens if you do!
Don't disgree, but these are also professionals. I'd gander to say that half the cheap "USB charge packs" sold by some random name are re-used cells. Wasnt that a big scandal of used cells being re packaged as "new" a few years back?

Yes, your right, should you use second hand stuff for critical applications? Probably not. Especially when your pushing them to their limits.
 
Also this project is all about fun and learning. If I ain't hurting myself I am not testing hard enough. But that being said I like all the comments on this thread. All great talking points.

My second stack of spim should be arriving in the next day or so. This weekend will be rainy, but I should be able to build it up in the garage even if I can't test it.
 
Don't disgree, but these are also professionals. I'd gander to say that half the cheap "USB charge packs" sold by some random name are re-used cells.
Those aren't professionals - just guys who knew what they are doing.

Note how the visitor asking the questions is an e-biker with knowledge that also claims 12 years from his batt. His recognition of how things are done right is part of that. Unlikely he is using random cells from the used aisle. Perhaps a TRUE A123 pack properly engineered for long-life, safety, and performance.
 
OK -- Now that you have us all hanging here --- How does it run/ride --- Any more Magic Smoke -- Hopefully no Red Liquid ( blood )
 
No more magic smoke. It rides nice and quiet. I still have to get my license and get this thing licensed and titled, so keeping it to my neighborhood only. I just have to do something with where the gas tank was, and get a replacement wind screen then it is off to DMV. Fingers crossed they will allow me to title/license it as a scooter.
 
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