When you receive your new cells, they should all be of a similar voltage, and it is typically recommended to balance all cells to the exact same state of charge before constructing the battery pack.
All you need to do is wire all eight of the cells together in parallel and let them stand for 24 hours
(or longer) to ensure they all stabilise at the same voltage before reconfiguring them into a series pack.
Your pack will require a
suitable Battery Management System that is rated for both the charge and discharge current requirements and the
BMS will be permanently connected to the pack to ensure that none of the cells are overloaded, overcharged or overdischarged. This prevents the battery from being accidentally discharged too low during use, therefore eliminating the risk of permanent cell damage.
After you have built the pack, the
BMS will commence balancing the cells at the end of each full charge during the constant voltage balancing/equalisation stage when the maximum pack/cell voltage is reached.
If you regularly perform partial charges, the
BMS will be unable to balance the cells and they may gradually go out of balance over a long period of time, but as long as the battery has a full charge at least once every month it should not be a problem.
Some useful information on Battery Management Systems can be found
here.
Alan
