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Battery Series-Parallel Calculator

Pack voltage, amp-hours, and energy from cell series/parallel counts, plus the cell counts needed to hit a target voltage and capacity.

Inputs

Cell and pack layout

Per cell: 3.2 V LiFePO4, 3.6-3.7 V NMC, 2.0 V lead-acid, 1.2 V NiMH.

Amp-hours of one cell at its nominal voltage (a 280 Ah LiFePO4 prismatic cell is 280 Ah).

Cells wired in series: voltage adds, amp-hours stay the same. 16S is the standard 48 V-class LiFePO4 layout.

Strings wired in parallel: amp-hours add, voltage stays the same.

Targets

Voltage class you are targeting. A "48 V" lithium pack is normally 16S of 3.2 V cells (51.2 V nominal) because inverters are rated by class, not by exact cell sum.

Energy you are trying to reach, used to report the total cells needed.

Result

Cells in this pack
16
Pack amp-hours
280.0 Ah
Pack energy
14.34 kWh
Pack voltage
51.2 V
Energy per cell
896.0 Wh
Cells needed for the target energy
16
Cells in series for the target voltage
15

What to check

  • Cell nominal voltage and the voltage class you need: a 48 V lithium pack is normally 16S of 3.2 V cells (51.2 V nominal).
  • Whether cell capacity is quoted at a continuous or pulse discharge rate; prismatic cells often list a 1C figure.
  • BMS compatibility: series count must match the BMS cell count, and the BMS current rating must cover the pack's parallel strings.
  • Whether cells are matched for capacity and internal resistance; mismatched parallel strings age unevenly.
  • Fuse or breaker rating per string, and cable size for the pack short-circuit current.

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Layout arithmetic only. It does not size a BMS, fuses, cable, or enclosure, and it does not verify that cells are matched or safe to combine. Follow the cell datasheet, the BMS requirements, and the locally adopted National Electrical Code (Article 706 for energy storage systems) before assembling or energizing a pack.

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