Some users and customers ask, why - when receiving the new cells – do the copper terminals have signs of severe oxidation.
Copper as a metal is prone to oxidation and reaction with other materials. The oxidation of the terminal is a matter of days. Also the black rubber cover on the top of the terminals may cause additional layer of the black rubber material to react with the pure copper and create a small layer of black -colored coating.
This is not a fault of failure. The copper (and also the aluminum) terminals must be cleaned and brushed by sand paper right before the assembly. This way any dirt or oxidation is removed and the terminals are perfectly clean.
GWL/Team encourages all customers to make the installation in the proper and correct way.
Check here for a suggestion: The cell terminals must be perfectly clean!