How to Calculate Battery Pack Energy at End-of-Life (EOL)

When calculating driving range theoretically, we assume 100% of total battery energy can be consumed. Practically, only 80%~90% of rated capacity is usable, subject to cell specification and actual operating conditions. The system is engineered to deliver 25kWh usable energy for 75-mile driving range. To reserve upper and lower SOC safety margins and restrict usable capacity to 80% of total energy, the required total pack energy is calculated as: 25kWh ÷ 0.8 = 31.25kWh

To output 25kWh usable power and achieve target mileage, the battery pack’s total rated energy shall exceed 31.25kWh. During customer communication, we must clarify whether the specified 25kWh refers to usable energy or nominal total energy. If the client takes 25kWh as total pack capacity, 20% energy will be locked for safety, leading to insufficient available power. In such case, a higher-capacity battery system is required to guarantee 25kWh usable output.

With confirmed total pack energy of 31.25kWh, we calculate pack capacity via formula: Ep​/Vp​=Ip​ Ep: total pack energy(kWh); Vp: pack nominal voltage(V); Ip: pack capacity(Ah) 31.25kWh ÷ 350V ≈ 90Ah

This design uses 96pcs of 3.7V 90Ah single cells in series to build a 350V, 31.25kWh complete battery pack. Distinguishing between total energy and usable energy is essential in battery design. To satisfy safety, service life and performance standards, nearly all lithium-ion batteries are prevented from full 100% discharge via BMS control.