Battery Series & Parallel Calculator
Work out the pack voltage, capacity and energy when you wire cells in series and parallel — the SxP configuration for any battery build.
How it works
Pack voltage = cell V × series · Pack capacity = cell mAh × parallel · Energy (Wh) = pack V × pack Ah
Wiring cells in series stacks their voltages while the capacity (amp-hours) stays the same; wiring them in parallel stacks the capacity while the voltage stays the same. A pack described as "3S2P" therefore has three cells’ voltage and two cells’ capacity, using six cells in total. Total stored energy in watt-hours is the pack voltage times the pack capacity in amp-hours, regardless of how the cells are arranged.
Worked example
Six 3.7 V, 3000 mAh cells in 3S2P give 3 × 3.7 = 11.1 V and 2 × 3000 = 6000 mAh (6 Ah). Energy is 11.1 × 6 = 66.6 Wh.
Frequently asked questions
Does series or parallel give more runtime?
Parallel does — it adds amp-hours at the same voltage, so a device draws the same current for longer. Series raises voltage (and therefore power at a given current) but not the amp-hour capacity.
Can I mix cells of different capacity or charge?
You should not. Cells in a pack should be the same type, capacity and charge level; mismatches make parallel cells fight each other and series strings become unbalanced, which stresses cells and can be dangerous with lithium chemistries.
How is watt-hour capacity different from amp-hours?
Amp-hours ignore voltage, so they only compare packs at the same voltage. Watt-hours (volts × amp-hours) measure actual energy and let you compare packs of different voltages fairly — it is also the figure airlines use for lithium battery limits.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.