Rev0 pack prototyping

Since I am still waiting for my motor adapter I have been doing some work on the battery pack.  I have tested the 8 cells I received and found the capacity ranged from 17.2ah to over 19.2ah. :(  Not very good for building a balanced pack.  I contacted the seller but have yet to hear back.  We'll see what happens but this is exactly why I ordered 8 first instead of jumping in to the full 220.  There are other suppliers of these cells that I am looking into so I have certainly not given up on them. 

I did some prototyping of a pack by making up some end plates so I could band the pack and get good compression on the cells.  Does anyone know how much pressure you need to need on the cells? 

My design uses a .120 aluminum sheet cut and bent to serve as endplates.  To make fabrication easier I made a plywood template for the flat pattern of the plates.  I should have used MDF but I happened to have a correct sized piece of ply laying around

I then used a .25" carbide router bit in a normal router and now I can make a blank in less then a minute.

I made one up using some scrap aluminium I had laying around and the first tab I bent promptly broke off.  I guess it's T6.  :)  So 30 seconds with the torch and I annealed it so I was able to bend it with hand tools.  Not ideal but works for proving out the design.

Here is how the end plate looks on 7 of the cells I have.

I am going to do a bit of tweaking  of the design and see if I get get some 6061-T0 otherwise I'll just aneall the stuff I have and make a prototype 1p8s pack.