Heh, same.
Cycle your battery a few times and keep an eye on charge and discharge uniformity. If group 4 continues to charge and discharge more quickly, pull it out, add as many welds to both sides of the groups as you safely can. Tbh, looks ok though⌠your delta is smaller as you reach a higher state of charge which is good. If you delta continued to grow and your bms couldnât bleed off enough to keep it within acceptable delta then Iâd be more concerned. Keep an eye on it. These arenât new cells if memory servesâŚ
2 Likes
Thx, but I think I found the problem. Do I have to strip off the nickel to get that one cell up to the voltage of the other cells in that group? Looks like I forgot to weld the negative side. Positive side looks good. I learned something todayâŚdonât pull all-nighters to finish your battery and ALWAYS double check your work. I love this battery building shyytđ¤đż
7 Likes
I noticed the more I drained the batteryâŚthe higher the delta. But the BMS managed to balance it out while charging
1 Like
Shiiite, Iâve done this before and the same way too. Working after work can really suck cause Iâm already drained. I think you need to pull the nickel and make sure to bring the cells all to the same level, before putting it back into the pack.
2 Likes
Yeah I knew that would be the caseâŚwell I guess I have to order more strips from @DuckBatterySystems. This sucks I wanted to get started in my 12s4p build this weekend.
2 Likes
Nah, itâs mostly touching anyway. Verify the voltage is nearly identical and weld, then balance. I wouldnât tearing it off and risk damaging the cells.
4 Likes
Good point, I guess I just assumed itâd be different by now
Whatâs the delta of the cell that wasnât welded?
1 Like
Theyâre all sitting at 4.03
1 Like
Lots of people build batteries (myself included) with reclaimed cells. Should be fine. Just try to get the surface as flat as possible. You can grind but they do rust. Best to try and use nippers/flatten as best as possible.
I can cut you a piece of nickel if you want. Iâve got a bit left over from a 100mm wide roll and you still have the extra 1 from Duck
6 Likes
thx bruh, Iâve already ordered another set from Duck.
2 Likes
I use a dremel and grind away just the nickel that was welded to the battery, but after cutting off as much as possible.
2 Likes
Thatâs annoying. I wouldâve prob just gone ahead and welded the fucker! Lol
In battery building, the devilâs in the details.
3 Likes
I know right. I was going to do just that but then I remembered that post from @Battery_Mooch about cells with different voltages in parallelâŚthat spooked the hell outta me. Lol
4 Likes
Ya I hear it. And Iâm always in favour of the adage âif you think it might be unsafe, assume it is until a trusted source tells you differentâ so ultimately you did the right thing. Solid first attempt bruv 
2 Likes
HmmâŚI donât remember posting about any grave danger when paralleling cells. 
In fact, I remember doing the math for calculating the current that might flow and it wasnât that bad unless you had high performance cells with big voltage differences.
4 Likes
ThxâŚthe first of many
Correct but the math scared me bruhâŚI was thinking what if that cell is way lower than the others.
2 Likes