Battery Pack Design Criteria and Selection 49 Calculating voltage (V): V = I Ч R V = ( P Ч R ) Calculating current (I): I = V/R I 2 = P/R I = P/V I p = E p /V p Calculating resistance (R): R = V/I R = P/I 2 Calculating power (P): P = I 2 Ч R P = V 2 /R P = V ( V/R ) Calculating Energy (E): E = V Ч I Number of series cells: Series cell = V p /V c Design Guidelines and Best Practices Perhaps the most important aspect of beginning to develop a new battery pack design is ensuring that you have a complete view and understanding of the customer’s actual require- ments. Many of the largest automotive original equipment manufacturers will generate very detailed and complex requirement documents.
This is the best scenario as it will give you a complete understanding of all of the various requirements. On the other hand, you may find yourself working with a small customer that does not have a set of requirements and you will be forced to work closely with them in order to gain a full under- standing of what they hope to achieve with the battery. At this stage it is important to ask as many questions as possible. I often find it valuable to begin by asking about the electric motor power requirements (how much power is needed) followed by the electric run time requirements (how long is it expected to run).
Once you begin collecting this type of information you can begin using some of the calculations above to help size the battery to meet the customer expectations.