Okay The OEM HV Toyota Pack comes with 7.2 nimh 6.5ah. How do you decide(personal preferences)IMHO on LifePO4 ah? There is a range of ah and voltages to choose from. For example ALLBattery has a Tenergy 7ah LifePo4 12volt now for sale, or say GBS Prismatic 3.2 40aH .