Requirements

PartQtyImageNotes
Battery Housing1

AliExpress:

https://www.aliexpress.com/item/1005005381700651.html?spm=a2g0o.order_list.order_list_main.11.43351802mqQ8Mr

18650 Litium Ion Batteries10

I had some of these kicking around. 

Test at about 2000 mAh each which would make this battery a 4Ah battery.

Spot Welder1

DIY Battery Spot Welder



Specifications

Configuration: 5s2p

Inside a Dewalt Knock-Off Battery 

I had another battery pulled apart to fix the thermistor so here is what it looks like inside.


Build

Spot welded the batteries and wrapped in kapton tape. 

Soldered on wires and inserted into battery base.

Assembled top portion


Final