18650 powerbank - 4 cell

This is a nice small and handy power bank. Built around the very popular 18650 li-ion cell. Also uses a handy charging/discharging module. Here is the link https://www.amazon.com/dp/B0CDWT9295?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_4

I used Eve 25v cells and a Seesii dual farand spot welder from Amazon https://www.amazon.com/dp/B0CY4KVTF1?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2

Spot weld some nickel strip to the cells and solder some wires (22 gauge minimum preferably) to the strip. Put some 5 mm material for padding (I used shipping foam) under and on top of the cells, then put isolating washer on top of cells. Solder wires to module. Careful they are live!!!! Then line up the case, washer, and end cap. I fastened mine with 1 inch #4 pan head sheet metal screws, but 1 1/4" screws would be better .  

Photos show one that I assembled. End cap didn't have verse on it yet. Used what wire I did have on hand and got tiny screws to fasten module from disassembled small electronics from my collection.   :-) Hole in side of end cap is for seeing the charge status lights.

Charging  is via usb-c input and discharging usb-a output

Caution!!!!      Lithium cells are dangerous!!!!        Make and use at your own risk!!!!