Update! Completed the battery build, this is a good bit of kit and I give it 2/5 stars for build difficulty and 4/5 stars for quality. In this build, I used 21 2400 mah 18650 batteries that will produce a max of 40ah with the battery management board. The cost of the total project not including tools less than $100.
I will have this battery and the spot welder used during the build at Ham and Eggs Breakfast on 3/19.