Battery Series Parallel Calculator

Estimate pack voltage, capacity, energy and total battery count from identical cells or batteries

Your result will appear here.

About the Battery Series Parallel Calculator

Battery series-parallel calculations show how voltage and amp-hour capacity change when identical batteries are arranged in series, parallel or a combination of both. Series raises voltage while parallel raises available amp-hour capacity.

The arrangement must use compatible batteries and proper balancing. The calculator describes nominal electrical totals, not the safety of mixing different chemistries, ages or states of charge.

How to Use the Battery Series Parallel Calculator

  1. Enter the voltage and amp-hour rating of one battery.
  2. Enter the number of batteries in each series string and the number of parallel strings.
  3. Calculate bank voltage, amp-hours and watt-hours.
  4. Confirm the physical battery configuration and protection scheme before building a real bank.

How the Calculation Works

For identical batteries in series, bank voltage = battery voltage × batteries per series string while Ah remains the same as one battery.

For identical series strings in parallel, Ah = single-string Ah × number of parallel strings while voltage remains the string voltage. Nominal Wh = bank voltage × bank Ah.

Worked example

Battery Series Parallel Calculator Worked Example

Four 12 V 100 Ah batteries as 2S2P

Two batteries in series give 24 V at 100 Ah. Two identical series strings in parallel give 24 V at 200 Ah. Nominal energy = 24×200 = 4,800 Wh.

Result guide

Understanding Your Battery Series Parallel Calculator Result

The arrangement changes voltage and amp-hour rating but does not create extra energy beyond the sum of the individual battery energies. Four identical 1,200 Wh batteries still provide 4,800 nominal Wh in either suitable arrangement.

Before you rely on the answer

Assumptions and Limitations

  • Batteries are identical in nominal voltage and capacity.
  • Series strings contain the same number of batteries before being paralleled.
  • Usable capacity, BMS limits and imbalance are outside the nominal arithmetic.

Practical tip

Using This Result in Practice

Do not parallel strings built from mismatched batteries. For lithium systems especially, follow the battery and BMS manufacturer’s approved series/parallel limits and protection requirements.

Related calculations

Useful Calculations to Continue With

If you need to size the total bank from a load and runtime target, use the Battery Capacity Calculator.

If the completed bank capacity is known and you want expected runtime, use the Battery Runtime Calculator.

Common questions

Battery Series Parallel Calculator FAQ

What happens when batteries are connected in series?

Voltages add while amp-hour capacity remains the same for identical batteries.

What happens in parallel?

Amp-hour capacities add while voltage remains the same for identical batteries.

Does series connection increase total watt-hours?

Adding more batteries increases total energy; series versus parallel mainly changes how that energy is presented as voltage and Ah.