Awesome, thanks! If you don't want cash, is there something else I might be able to do for you, as a token of my appreciation? PM me an address so I can mail things to you (doesn't have to be your home address, for privacy).
Would you like a resistance soldering rig? I am building one for myself, and I have two extra transformers I don't need.
If anyone wants to print up a set of these cell-caps and sell them, have at it. I hope you make a healthy profit. You owe me nothing.
...although, if you are making a profit from these, and we meet someday?...I would not turn down the offer of a beer.
In this pic, all of the series connections are made using common pure nickel 7mm wide strips, 0.20mm thick. If we are using cells that are rated for 10A, then each strip shown will provide 10A peak, for a pack total of 40A, in a 4P (four cells in parallel) configuration. It doesn't matter if this is a 10S (36V) or a 13S (48V) pack, the construction would be the same for 4P at 40A.
At this stage of the construction, the pack needs paralleling wires added, but they can be soldered to the nickel strips. The amount of amps carried by each wire is the max difference between two matched cells during charge and discharge. As long as the voltage in each cell is fairly close to its neighbor, the paralleling current would be less than 1/2 amp. There are several ways to attach them, such as being soldered or spot-welded (use solid wire for spot-welding, instead of stranded). By attaching them to the nickel strips halfway between the two connected cells, there is absolutely no danger of heat damage to any cell, regardless of the method used.
I know sometimes a new device can have its performance hindered if the committee designing it wants it to allow "all options". The beauty of open-source is that anyone can take this idea and optimize it for a specific design, by making a small tweak.
For rectangular "rank and file" shapes of battery packs, there already exists several kits for building a pack. I like the staggered "honeycomb" layout, because I think it is useful to use that for adding some type of air-flow fans. Of course, some existing honeycombed packs do not have an air-fan, so...you don't have to want fans to like the honeycomb layout.
As to options...should the builder use solder, spot-welding, or use resistance soldering? (a new thing around here). Choose the method you like, and please post the results.
Bus material...My research leads me to believe that...for 30A pack, there is nothing wrong with the common method of using 0.15mm thick nickel strips that are spot-welded onto the cell tips (at 4P, 30A would be 7.7A per cell, and per bus-strip) . But...when someone wants to use the full 30A of a 21700 cell, or maybe a pack of 15A 30Q cells (one of my top-2 favorites), nickel will get hot, no matter how thick you make it. The amount of wasted watts heating the nickel buses, and the voltage drop across the resistance of nickel buses...it may be small, but...some builders want to look at upgrade options, so why not?
I believe the series bus material should be copper or aluminum, either raw or nickel-plated. If you disagree, please build your pack to your desired spec, and post the results. If you are happy with it, I am happy for you. I am hoping this end cap design allows builders who use it to access all of these options listed above.
"Common pack design mistakes, how to avoid?"
https://endless-sphere.com/forums/viewt ... 14&t=84412
Honeycomb plastic cell grids already exist, but they are only for 18650 cells, no 21700 option, plus there is only one size of spacing, there is no option to increase spacing slightly for better air-flow.