Battery Series/Parallel Calculator

Enter your battery specs and configuration to compute pack voltage, capacity (Ah), and energy (Wh). Share links restore state.

How to Use

  1. Enter a single battery’s nominal voltage and capacity (Ah).
  2. Choose how many cells are in series (S) and how many strings are in parallel (P).
  3. Optionally enter max continuous current (A) per cell and efficiency to estimate usable power.
  4. Open “Show Work” for formulas and steps.
Pack Overview
Live outputs update as you type (no URL changes).
Vpack
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Ah
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Wh
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Imax
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Status: —
Inputs & Settings
Nominal values are for planning only. Use matched cells and proper BMS/fusing in real builds.
Examples: 1.2V (NiMH), 2.0V (lead cell), 3.2V (LiFePO4), 3.7V (Li-ion)
Capacity adds in parallel; stays the same in series.
Series increases voltage: Vpack = Vcell × S
Parallel increases capacity/current: Ahpack = Ahcell × P
Optional. Pack Imax ≈ Icell × P (planning estimate).
Optional. Usable Wh ≈ Wh × (eff/100).
Show Work (step-by-step)
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Work is shown using base units (V, Ah, Wh, A) for clarity.

Formulas

  • Series (S): Vpack = Vcell × S
  • Parallel (P): Ahpack = Ahcell × P
  • Energy: Wh = Vpack × Ahpack
  • Usable energy: Whusable = Wh × (eff/100)
  • Max current (estimate): Imax ≈ Icell × P
Notes: Real-world voltage varies with state-of-charge, load, and chemistry. Use correct BMS and fusing.

FAQ

Does series increase capacity (Ah)?

No. Series increases voltage. Capacity (Ah) stays the same as a single battery (per string).

Does parallel increase voltage?

No. Parallel increases capacity (Ah) and potential current capability (depending on cell limits).

Can I mix different batteries?

For safety and performance, avoid mixing different chemistries, capacities, ages, or internal resistance—especially in parallel.

Why is my “Wh” estimate different from reality?

Losses come from voltage sag, inverter/ESC efficiency, wiring, temperature, and cutoffs. Use the efficiency field for a rough usable estimate.

Tool Info

Last updated:

Updates may include more chemistry presets, validation rules, and edge-case handling.