Must say V2 kit is overall higher quality and consistency than V1, good job.
0.5x8mm nickel coated copper, 4mm2.
Contact neck is 0.75x6mm nickel coated copper, 4.5mm2. There is kind of stopper plate on the back side of the contact which is copper to and you will loose some resistance if compressed to the point where stopper sits on the screw head.
Screw and nut:
look like SS but distance to copper is very short. (EDIT:
Urvakhsha wrote its Brass-Copper alloy
and indeed, I sanded another nut and bolt, they have yellow shimmer I must have overseen at first.)
V values are measured from cells can to the screw of adjacent cell, R is calculated by simple V=IR.
There are 3 values I could separate and I think are relevant:
R per cap, multiply by 2 for a per cell added resistance.
1. 0.0012Ohm/0.035Vx 30A=1.05W of heat. Perfect contact
, where compression is enough to press stopper and screw head together + cell-cap sitting flat on the contact.
2. 0.0015Ohm/0.045Vx30A=1.35W of heat. Cell not flat
, where compression is enough to press stopper and screw head together but cell-cap is not sitting flat on the contact. (I just moved cell out of right angle)
3. 0.0025Ohm/0.075Vx30A=2.25W of heat. Not compressed completely
, stopper and screw-head apart and apparently no flat contact.
1.There is no 18650 cell, I know, that can sustain discharge/charge long enough to get the V2 cap to vicat.
2.Every 18650 cell I know will produce substantially more heat then Vruzend interconnections. (I used A123 18650 cells)
3.Considering previous, when cells get to the vicat temperature of the caps (cell is the heating element), they will be permanently damaged and venting already.
Mathematically, it is not possible in real world application (real world existing cells) but I will try to simulate a scenario and get those caps melted to see the limit, just need some way to get enough current flow.
Congratulation, extraordinary good job Urvakhsha and Micah !!!
Boring pictures below: