Well its perfectly understandable that they don’t want to talk about details before they fully understand it themselfes? Sometimes the hate here baffles me. Chill the fuck out and wait for the patch notes, the fuck
13 Likes
We think in a combination of three different things going wrong at once, a problem could pop up.
This is not limited to our pack BTW. We can catch that scenario and prevent things from going south in such a situation.
3 Likes
This has been an issue for years and years. Lower grade cells, badly stored old stock, and fakes have been a plague for a long time and will continue to be. Especially since so many companies and individuals buy just based on price…huge mistake.
Just a side note…
It’s very easy to sort these crappy cells from true higher grade ones. There’s no good excuse for any company finding itself using these cells in their products (not pointing at any particular company here!).
5 Likes
I am not even slightly baffled as to why Frank doesn’t have an easy time here.
Bad behavior has consequences. 
@Trampa it would be great if you guys could post a report as to what went wrong when you’re finished. It could be valuable learning for others with safety involved.
5 Likes
Is it? Say that I have 100 cells on hand that I need to check. What would be the easy way to do it? (No sarcasm. Genuinely asking.)
Edit: After some thinking. Obviously checking voltage to identify suspicious cells is quick. But beyond that, with the equipment I have readily available, I could probably make a holder for 12 cells in series connected to a charge/discharge BMS and then charge and discharge the 12S1P pack. Bad cells would get out balance with the other. I would need to repeat this 9 times if I’m to check 100 cells. It’s surely doable but not exactly easy.
3 Likes
Agreed it’s a very novel take on battery building and a cool way to do it. However, i have to point out that’s it’s just as easy (potentially easier, less steps) to commission a complete pack from a professional builder for almost the exact same price.
I’m still unclear on the advantage to the trampa PCB jigsaw puzzle beside novelty. There’s no cost or reliability improvement.
1 Like
I mean… yeah, but that completely misses the point lol
The point is that you could replace the cells and use the same framework, and if you do want to do it yourself, no welding is required
Edit: it also gets around shipping cells to countries where shipping cells is annoying, also, you can pick any cell of that size that you want. It is also theoretically compatible with both 21700 and 18650 just by changing the hole size on the puzzle piece
The best way, IMO, is to run a performance check on each cell. You can the test self-discharge rate, the capacity, and the DC IR but all that comes out in a performance test anyway. A physical examination can quickly point out the bad fakes and is usually worth doing to prevent wasting time testing the cell.
Cycle the cell twice at a moderate rate, perhaps a third to half of its continuous current rating. Check for an increase in capacity for the second cycle that could be the result of a recovery of some capacity lost in during storage for a very long time. Then do a discharge at the cells continuous current rating, comparing its performance to a known genuine high grade cell. The difference in performance for lower grade and fakes is usually easy to spot. Occasionally you might have to test two or three suspect cells to make sure.
Make sure no cell ever goes over about 80°C for a moderate to high power cell and not over about 65°C for an ultra-high capacity energy cell.
The quick version?
Just discharge the cell at its continuous current rating down to 2.5V and compare its performance to a known genuine cell.
6 Likes
This x100 makes battery building not possible financially.
I rather leave this to who I buy the cells from. Official resellers only.
4 Likes
A spot check of your purchase, one to a few cells at most, is all that’s needed as long as they all are from the same batch.
The quicker quick version?
Test the DC IR. But very good fakes can have a very similar DC IR.
2 Likes
I disagree that it misses the point. I don’t think that scenario is a common use case at all. How many people have diy boards (already a niche), mountain boards specifically (smaller niche), that ride a battery pack 2-3 years until it’s deep into the end of it’s lifespan (even smaller niche) and then fully replace all the cells with new ones.
At that point, yes, you benefit by only having to buy cells.
But for a similar initial upfront cost, you could buy a fully built and arguably more rugged batter pack, and not have to do any work at all.
Edit: great comments above, i didn’t consider. With trampas setup you also need to be relatively well informed/knowledgeable about sourcing your own cells (and testing, ideally). Which gets away from the easy-diy benefit of the assembly.
To be clear, i still think it’s very cool, i just don’t see any real competitive advantage. If there was a significant cost savings, this would be a different conversation
2 Likes
Okay well I would argue that assembly is probably a quarter of the time or less
Who have you compared the prices to? 12s7p packs are pretty pricey
I also wonder if the price will maybe decrease in the future, but hard to say
1 Like
Despite your recent attempts to eviscerate your reputation, this is a valid point.
8 Likes
Oh yeah, for sure it’s less, and less messy. But if the price is similar, the customer isn’t doing any assembly at all with a traditional battery pack. So 0 time vs an hour? or whatever it is.
Sidenote:
I just looked at trampa’s product listings. I could be wrong, but it looks like the 21700 kit and the 18650 kit are two distinct products. To switch between the two battery sizes it seems like it’s more than just the “glass-fiber cell spacer” piece. Plus the 21700 kit requires the “Massive Monster Box” vs the original box, so it doesn’t appear that they intend the customer to swap sizes.
On cost, this was the rough calc I did when I was shopping out a build:
- Trampa - pcb kit for 18650s - $470 (+$5/ea P26A cell: +$250-420) = $700 to $900
- Trampa - pcb kit for 21700s - $540 (+$6/ea P42A cell: +$300-500) = $840 to $1040
- Battery builder - custom brick pack, 12s4p to 12s7p P42A - $600 to $1000
@thisguyhere, as of january (eons ago) when he gave me a breakdown, was charging ~$3.25/cell + $50 bms. He was on the less expensive side of the spectrum, but for 84 cells that’s $273 in labor and materials + $50. That’s ~half the price of the trampa 21700 kit.
At $5/cell labor, that’s still $420, cheaper than the 21700 kit. Break even is $6/cell labor. More expensive if you use less cells than the max. But point remains, that you only begin to see real cost savings when you put in that 2nd set of cells.
Oh I did not know this
Yeah as for the builder price, I would think 6 a cell is kind of normal now, but I’ve never actually bought a pack either.
Who knows then, they wouldn’t be selling it if it didn’t make something better for trampa
12S8P = £650 
CNC cell holders, laser cut nickel, PCB based, smart BMS etc
7 Likes
-
ring was free floating
-
Line1 - L0HB
Line 2 - 6B881
Line 3 - W13
Line 4 - B01
Line 5 - C01
-
backwards y
-
looks like C0
3 Likes
IMO everything points to those being genuine. 
I’m wondering what’s going on though at the circled points in the image below. Point A almost looks like an opening in the seal and Point B looks like a burn mark? Those shouldn’t be there.
3 Likes
If I were to guess, I’d say the welder electrode missed, pulsing the nickel over the gap.
2 Likes