Check the highlight from the GWL Video - GWL/Power: Starting with LYP/LFP cells from Winston Battery - 13 steps

QUOTE: 

Use only the original copper terminals #1). There are many reasons why you should not use any other accessories #2) to connect the cells. Check our knowledge-base for details #3), if you are interested in. It is very important to clean all connectors and terminals perfectly with sandpaper just before assembly. #4). Even small resistance between the cells would dis-balance the battery.  

NOTES:

#1 – if you use other than copper terminals you, the connection between the cells will be less than perfect and you lose the energy. 

#2 – the recommendation is to use the quality copper terminals, not some other replacement solutions (with low quality materials). 

#3 – see information like this:

• The high-quality copper terminal connectors
• Cleaning all the battery terminals with a wire brush before you connect them up makes a remarkable difference to how the pack performs.
• The Battery Packs with Corroded Terminals
• Cell damaged by short circuit and over charge

#4) the final cleaning of the terminals must be done right before the assembly, the oxidation of the copper is rather quick and the oxidated surface will increase the resistance of the terminals.