The voltage and temperature of each cell in the fully assembled battery will be subjected to repeated load tests of 18 kw over periods of 40-45 sec. “For every battery in service we have a manufacturing record, so we know how each one of the cells behaved when they were tested. We know today which cells will not pass the screening tests and when they return from the fleet we will reject those cells. In addition, they will still be tested when they are refurbished,” says Hinderbeger. He adds that 115 batteries are currently in the field.