This photo shows the condition of the cell terminals when   operated in aggressive and corrosive environments.  

In this case the customer has been operating the cells for many years already. Even though there is no longer the manufacturer’s warranty for the product, the   GWL/Team has provided the extended support to this customer.   The customer claimed that some of the packs show significantly poorer performance than others. GWl/Team investigated these packs. The results show that the issues is improper use by the customer. Due to the extremely aggressive environment the terminals have corroded and could cause the difference of performance against the packs that were kept in perfect shape.

Conclusion: the performance of the cells depends on the environment and   the influence of the external environment may be very significant,   resulting in quick deterioration especially if the condition of the terminals is not inspected periodically.