I take back what I said earlier… Those BHU 6Ah cell that I thought were garbage (1.2-1.7V) actually tested above 6Ah, one as high as 6.275Ah so I guess they’re just like that? Just really strange excessive self-discharge if you leave them too long although mine were from July 2020 but they didn’t behave any differently from the cells that had only discharged to 3.25V after being cycled just one single time.
Interesting. I’ll definitely keep an eye on them.
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Check out dis newbie (40t3) at 18650 battery store. Only downfall is they are 9.99 each. @Battery_Mooch we now need these tested against the p42
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Umm….
For anyone looking to have a popular cell tested that I have not tested before, I’m happy to put in the two days of testing if you send me four of each cell (two if a big name manufacturer). Contact me via PM to make the arrangements.
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I was gonna say… Lmao
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Any critiques on my battery building? It’s a rebuild of my old poorly made 12s3p pack into a 10s4p 25r pack with proper techniques. Used neutral cure silicone for each p group, surrounded by fish paper and @BenjaminF fish paper rings, use a small bit of Kapton to ensure the edge cannot get caught. Using a Boss welder (pack supplied by @Fosterqc… Thank you 
) and 0.2mm pre cut nickel (tinned with blobs as well) and four welds per cell. The tabs of the nickel are bent over the edge of the p group using the cell ring circles to double up the fish paper and lessen the chance of wear. Lastly the p groups are connected together with 2x 12awg high strand count silicone wires from turnigy. I’ve Still got alot to go until it’s complete but I figured I should ask before I get too deep. Thanks!
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lol! was thinking about asking how many more cells you needed haha. LMK if it gives out on you.
Could have gone down an AWG on the series wires I think, good idea to give extra in case one somehow came off I guess.
Looking good, up next mastering the balance wire arrangement!
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I had actually started out with 10awg but it was just too stiff and flexing the nickel rather than the wire, it’d work better in a segmented enclosure where you can have >1.5" of wire. Tinned copper braid would be best in this situation? But it’s PRICEY and is it necessary?
I’ve got a plan for it!
Nope it seems to be okay, trickle charged it for a few days, we still have to use a longer delay than we’d like on the welder (some welds are a little hot) but if we want to fix it we could probably get a 3rd parallel pack 
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I think he meant down in size (up in gauge) to 14. Double 12 should be very sufficient for a 4p pack.
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I did a brain dumb yes
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I just got some P42a cells for a build from M&A BD Electronics in California. The store seems legitimate, but the printing on the wrappers is different from what I’ve gotten before.
I’m assuming I’m just silly, but I’d rather ask.
Cell on the right is from 18650BatteryStore, cell on the left is the new one from M&A BD Electronics.
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Not silly at all, there are a huge number of fakes of that cell being sold worldwide. It’s one of the hazards when not buying from an authorized vendor.
The M&A cell is 2018-dated. The 18650BatteryStore cell is 2019 dated. This might explain the different style of printing. Different factories and assembly lines can use different printers too.
You’ll need to take one of each out of their wraps and very, very carefully compare them using a magnifier. If the black top insulating ring is self-adhesive then it’s definitely a fake though.
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Thank you for your help.
I’ll do that.
What should I be looking for, aside from the adhesive ring?
I usually go through batches of cells with an impedance tester just to make sure they’re relatively even after checking voltages for any DOA. But if I need to open wraps for the cells, I can do that.
Any specific things? Or should I just post photos of what I find?
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Please do this, I am curious.
What are the risks of using a cell this old? I know about calendar ageing, and I know it’s impossible for you to guess how much degradation that cell has actually suffered from sitting for that long.
I guess I’m wondering how old is “too old” if I am looking to buy only top-quality cells for my business.
Video has sound but no picture, please upload a youtube link or something.
From the sounds, I’m assuming that video is showing an adhesive top plastic ring?
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Will do. Uploading it now. I’ll edit the post when I have the link.
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Correct.
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