if you read the battery experts on endless sphere: 18650 spot welding -how to- ULTIMATE REPOSITORY | Endless Sphere DIY EV Forum
then 7x0.15mm thickness is good for about 7A and becomes hot @ 10A already. with 10mm width, that means its good for about 10A and becomes hot at about 15A already (that table is set up for the typical lengths of nickel strips in 18650 builds, i.e. about 30mm. if you make longer connections, the strip resistance increases linearly with length and so does the overall ohmic heat and therefore your losses).
Im always surprised about all these apparently poorly welded battery serial connections in nearly ALL builds I read about.
Yeah but Enertion has strips for each cell. Each cell will only reach around 15A current draw at peaks. The 40A fuse stops it from doing anymore. That is why I thought it would be okay. Guess I was wrong. Here’s a pic showing what I mean.
there are more serial connections than just the connecting middle ones!
this is my last battery - the middle serial connections I also went with 1 strip per cell … which is not enough with a 20A cell but since its only 30mm short I felt this connection was halfway ok - most often you ask these 20A only for a few seconds anyway:
now the other serial connections on the outside of the battery after its folded:
guess you could use multiple strips and weld them on top of each other or so - at least 3 to match the middle serial strips.
does anyone have a specific link to a good pure nickel strip? all the ones that I am finding are either not the right dimensions or they are nickel plated.
@Lewishong, here is a linkie to the ones I used. They might be slightly under-rated for a high-powered board, but this gives you a starting point on your search:
on my latest battery I really just added 3-4 nickel strips on top of each other like @Maxid asked. even less soldering heat, but takes a little longer compared to soldering copper strips.
@deucesdown got me into the folded 30mm strip but can’t find it. Anyone have a source of 30mm at .2mm or even .15? As said above if u look at ampacity ratings as decided by people on es everyone pack seems way low even on just the nickel parallel connections.