This battery pack calculator helps you instantly compute final pack voltage and total capacity for banks built from identical cells. Here's a useful battery pack calculator for calculating the parameters of battery packs, including lithium-ion batteries. Hobbyists building a powerwall, engineers crafting an electric vehicle battery, and tinkerers assembling portable gadgets all face the same puzzle: how many cells. Enter your target voltage, capacity, and cell specs. Battery performance varies with temperature, age, charge cycles, and depth of discharge. These results are theoretical estimates based on manufacturer-rated capacity. Real-world runtime may be 10–20% lower.