Guess I can contribute now. Just finished my first pack for the evolve gtx. Still awaiting crimps for the balance plug but hopefully take it for a spin tomorrow
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First 3S2P group done. Three more to go. Stats so far:
- wires cut: 12
- pieces of insulation stripped: 24
- solder joins made: 24
- shorts across the solder wire that made a splendid spark: 1
Flex test:
Note the middle corridor for routing the balance leads. Patent pending.
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They’re so pretty!
Unfortunately all that fish paper around my p groups made my battery a tiny bit to large for the evolve enclosure. I found a riser online and modified it to 8mm. Something I’ll know for. Next time I guess.
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Love the ribbon cable!
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I have a battery related question, couldn’t find anything so far.
I have a 10S3P LG-HG2 Pack and noticed that my first P-group, the one connected to the negative output, is discharging/ dropping in voltage faster than the other 9 P-groups.
I thought on of the cells in that group might me defective and doesn’t have it’s full capacity but after taking the first P-group out of the pack and checking all 3 cells individually they all have the same, advertised capacity of around 3000 mAh.
I don’t know what else could cause one P-group to discharge faster than the others.
Anyone here has any ideas or things I should check?
How big is the difference to other p packs?
I have seen similar on different lipos that the first cell discharged deeper than the other cells in the pack. Maybe because it’s first cell it get a bit more stress.
But it was never really so much that it wasn’t possible to balance it out during charging.
P-group one hit 2,5V triggering the battery cutoff of my DieBieMS while the other 9 where still at around 3,3V/3,4V
Thats a huge difference 
how where the cells connected? Maybe there was a bad connection between the 3 cells?
I had that idea too, but they all looked fine, nothing was loose and it took quite some force to get the nickel of the cells.
So I don’t think I had bad welds.
when you took the p-group apart and looked at the 3 cells individually and they all were 3ah capacity how did you test?
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Do you have a bestech BMS? There was a bad batch from them that cause 1st p group to drain like that. @thisguyhere I think knows more.
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Charged the 3 cells, still connected as a 3P-group, to 4,2V, took it apart, discharged each cell with the discharge function of my iMAX B6 @ 1A to 3V and looked what capacity it showed me.
The math also checks out: 3000 mAh @ 1A = 3 hours for discharge or 16,6 mAh per minute wich was exactly what I got.
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No, I have a DieBieMS
seen cell 1 drain out a number of times, but for me, i just replaced the bms.
for @pookybear’s last battery, i had to go through 3 bms before it worked again.
if not that, see if the internal resistance in that P group of drastically different. i think the b6 has a way to get the IR reading.
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ok, I’ll see if I can get the IR of the 3 cells.
OK, I calculated the internal resistance of my cells by first measuring the open voltage, then measuring the voltage drop with a 1 ohm resistor on the cell and then calculated the IR with Ohm’s and Kirchhoff’s law.
I get around 50 to 60 mOhm per cell, including the “good” ones in my pack.
Hi everyone! I’m joining the club 
+1 in wanting to read @Zach’s battery building guide.
I’m planning to build a few battery packs, and had some questions I was unable to find answers for. (Spent the past 3h reading through all the battery threads I could find, so I’ve done my homework)
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(Answered) I haven’t bought a spot welder yet. I want something compact so that I can take it with me when traveling. kWeld VS Boss level welder sold by aluakiria. Seems like the boss welder is way more powerful, but the kWeld is available as a kit with everything. Also have heard reports of people’s boss welders breaking / some functionality not working after a while.
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I’ve read that nickel strips can’t carry much current. I plan on building my packs with PCBs for each parallel group (cause all the cool kids are doing it), so I only need nickel to connect the cells to the PCB. However, for something like a 40T cell that can do 30A, that’s a whole lot of nickel! Do people weld nickel onto nickel for powerful packs like that, or move on to copper, or what?
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(Answered) What do you use to cut the nickel strips? Would sheet metal scissors work?
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(Answered) What do you use to flatten the nickel after doing a cut? One of those metal clamps that screw on to tables?
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(Answered) @EboardSolutions are the nickel strips you sell on your site pure nickel, or just nickel plated steel?
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(Answered) When to use fishpaper, when to use kapton tape?
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If I only use non-corrosive materials, why do I have to worry about water getting into my pack? (As long as my BMS has conformal coating and the whole enclosure isn’t flooded lol)
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(Answered) Anyone know of a good place to source silicon coated stranded copper wire in the EU? My hardware stores suck and electronics stores fine a premium. Same question about where to purchase fuses for the charging port.
Sorry for the long read, any help is appreciated 
Kweld can weld with currents up to 2000A, and thats with a safety coefficient of 5 , its in another league compared to boss level, for just a few batteries 8 would go with the boss level because its a lot cheaper, its totally good for diy people who do not need to make a battery fast/often
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