Battery series/parallel calculator
Calculate nominal battery-bank volts, amp-hours, watt-hours, and total battery count for identical batteries in series and parallel.
Size storage from your daily energy first, then compare the nominal Ah at the same voltage. Check balanced current paths and permitted string counts in the battery manual.
Enter your system assumptions
Formula and assumptions
bank V = battery V × series count; bank Ah = battery Ah × parallel strings; Wh = bank V × bank Ah; total batteries = series × parallelUse identical batteries and equal strings. Integer counts are required. This arithmetic does not confirm that your manufacturer permits series or parallel connections; verify BMS and charger compatibility before assembly.
Worked example
Four 12 V, 100 Ah batteries in two series pairs connected in parallel give 24 V, 200 Ah, and 4,800 Wh. Four in parallel instead give 12 V and 400 Ah, with the same nominal 4,800 Wh.
Frequently asked questions
Does series wiring increase amp-hours?
No. Series adds voltage while the Ah rating stays the same for identical batteries. Parallel adds Ah at the same voltage.
Is nominal capacity all usable?
No. Depth of discharge, reserve, conversion losses, temperature, and battery condition reduce delivered energy. Use the bank and runtime calculator to apply those assumptions.