thanks think you right
If the welds show burn marks itās usually a bit much.
Iām sorry if thatās not a right group to post it but Iām a noobie and I need a little help before I start building .
Just recieved last part needed for my skateboard. I want to start building battery tomorrow using Samsung Q30 and NESE 2s4p modules - to create 10s4p pack. Iām also using DieBieMS with discharge and charge setup. Can you please review my build plan so i dont destroy my BMS or Q30 cells. Thanks a lot!!!
Also thatās my first build so sorry for shitty discription and plan.
I thort that but if you look at the back itās not leaving behind any nickel I think I need more preset and holes in the nickel to force the current thro the nickel in to the battery as it appears most is tracking thro the Nickle alone with out penetrating in to the battery.
For now iv gone back to 0.15 will reinforce it with flat 10mm by 1mm tined copper braid.
Cool, is that a K Weld? What power source are you using?
1 Like
Your diagram looks good to me. Have fun building!
1 Like
Hey nice welder. 
I tried .25mm and .30mm nickel, and it could make good welds but I felt there was too much energy going in. Everything got very hot. Seemed better to solder copper wire to the cells at that point. iirc about 60 joules is the most I feel comfortable using on 18650.
Splitting the nickel will probably help, but that is not a convenient operation as far as I can figure.
1 Like
Need help with BMS
Iām using this BMS bypassing discharge. Itās a 13s BMS but Iām using it for a 12s3p 30Q pack. I followed the schematic except for the last wire.
My problem is:
B- to B12 = 49.0V
B- to B13 = 0.0V
Main + and Main - = 49.0 V (Bypassing Discharge)
Main + and C- = 43.9 V
Main + and P- = 43.9 V
Anyone know whatās happening here?
why? iām not even sure that works. there was some anecdotal evidence you can use higher S count bms on lower voltage packs but nothing confirmed.
in your diagram, B13 lead is pack+, but thatās already connected to B12 lead so not sure how you can get around that.
mmmā¦iād rather find a 12S bms.
comon brosef, why you gotta make me link this?
1 Like
difference is bestech bms balance leads donāt attach to pack+ and pack-.
(diff model but same idea)
whereas the one thatās being used here, highest and lowest balance leads DO attach to pack+ and pack-.
also, that post by @scepterr, thatās an initial finding and he said heās need further confirmation. then that thread digresses into using multiple low S count bms to balance higher S count packs. i was there when that happened.
1 Like
I thought the balance leads are always + and - except for the B-. Been reading through the thread linked above. Got this from a post by @deckoz.
I just want to know if this is normal behavior when using a higher series BMS for a lower series pack.
@deckoz Yeah it does make sense. Thatās why I donāt understand whatās happening with my setup. Could it be a dud BMS?
Cells are 4.05 Ā± 0.01. So this could be defective BMS then. Maybe Iāll extend the pack to a 13s and test if it behaves the same way. Then I have a legitimate reason to get a refund or a replacement from the seller. Thanks!
Silly ideaā¦ If I built 2 batteries and wired them in parallel, one with 40t one with 30t, each with its own bms for charge only - would there be problems ?
Itās basically the same as if you mixed up 40T and 30T in your P groups. It would work but itās no good for the cells.
I would imagine that ultimately if you set your current draw too high, the 30Tās would degrade a lot faster than the 40Tās
I get why mixing in the same p group is bad but hoped at battery level it might workā¦
I started to wonder why we donāt have a smart discharge system capable of using different cell types, use the quick burst from cell type a, and range capability of type b
Edit: love the idea of a much smaller boost pack within the battery to cope with sag better 
2 Likes
Donāt you just divide the resistance by the number of cells?
So, wouldnāt it be 2mohm for the 3 x 30T, and 1.8mohm for 6 x 30q?
1 Like