Oo yea with the welds u don’t want any flex.
Nope, ultra capacity 18650 cells just recently got to 4000mAh with the vapcell n40 (who knows who’s actually making them), so 20000 is a nonsense number
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Nope.
The highest you’ll get with a 10s4p is 16Ah, and even that is pushing it, with 4000 mAh cells which are really uncommon. The highest you’re likely to see in the real world is 14Ah with NCR18650GA 3.5Ah cells or 11.2Ah with Molicel P28A 2.8Ah cells.
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Classic Ali battery
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I found it in a “revised” e-bike battery
Are they definitely 18650? Maybe 21700? But it’s LG too
Or Panasonic have a 5ah 21700 too:
Not if 18650.
I’m thinking it’s the Panasonic NCR21700A 5000mAh 21700, sometimes referred to as the “Tesla” 21700. Probably a 10A-15A cell.
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It’s just a fake
I deal with people asking me to repair these constantly. I’ve done a few for friends, most of the time cells in there just fail…
Most of them actually use either sand cells (literally 100% fake) or more likely DLG 2700/BAK 2500 cells, 8-12A current. So 20ah but its actually 10Ah or less if its fake cells entirely.
Because ebikers almost never run it down in 1 go (especially with pedal assist, practically required for the crappy motors and ESCs this is paired with) so they never know they’ve essentially been scammed
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Those are the safest
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Well my this bike has a throttle so it was easily noticable.
Yep, that’s when its obvious.
I have a LOT of trouble with these scam amazon batteries though. Too many of my ebike commissions are replacing these, and people think it just broke etc rather than they never had that capacity and its impossible to build that capacity for the price or space…
I actually end up cheaper than china for most people too (The cells are barely marked up in the UK, so its just building fees and with efficient building, its possible to undercut anyone and still make 40$/hour) but their perspective is warped by ali/amazon scams like that 
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Does this look reasonable for a pull test?
On two of the weld pairs, one side ripped the nickel but the other didn’t. The same thing happened in some practice welds last night and I swapped the tips to check if it was uneven hand pressure, and now the other side didn’t stick as well so I take it it’s the copper tip. I redressed them but the point might have been too fine because it only lasted a weld or too. What sort of size point is meant when people say “sharp”?
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Someone else can definitely answer better than I can, but I had a little experience with this as well. Those tears looks nice, but you’re right, the other half doesn’t look great. As far as I’m aware, at least for me, it isn’t about pressure, but it’s the spot welder or power supply. Unfortunately I was getting the same half the welds are good, other don’t tear much. But that was with .2mm. With .15, I got really even and clean welds. What spot welder are you using? I’m using the Squere SW-1.
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Also does anyone have a good high power soldering iron recommendation? I’ve been using a cheep 60w one for awhile, but it definitely struggles with anything close to 10awg. Anyone have a recommendation for something that can do up to 6awg without issues? Thanks
Thanks, I forgot I didn’t mention it but I’m also using the Sequre. It’s a 5.5Ah “140C” lipo so being slightly low power makes sense. I think I’ll give it plenty of time to cool down and recharge often
The pictured test welds were on a AA battery, once I got more comfortable I did a test weld on an extra of the cell I’m using for the pack and it came out better. The AA has uneven height on the negative terminal so it was hard to make consistent contact
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Ah that would make sense. Hopefully it goes well with a full charge.
I sometimes use a stanley blade as a tester. Seems to give a good reflection of how well the welds are working.
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