Battery Pack Calculator: Series/Parallel, Energy, Charge Time and Charging Power
Series / parallel pack voltage, capacity and energy, charge time, and AC / DC charging power.
Pack
Charging time
Results
Charging power from voltage and current
Pack V = S × cell V; capacity = P × cell Ah; energy = V × Ah. Charge time ignores the constant-voltage taper and thermal limits, so real charging takes longer than this linear estimate. Three-phase AC: P = √3 · V(line) · I · PF; single-phase: V · I · PF; DC: V · I. Charging standards (IEC 61851, SAE J1772, CCS) set the real limits.
C-rate
Frequently asked questions
How do I size a battery pack from cells?
Cells in series add voltage (pack voltage = series count × cell voltage); cells in parallel add capacity (pack Ah = parallel count × cell Ah). Energy in Wh is voltage × Ah, and the current at a C-rate is the C-rate × capacity in Ah.
For preliminary assessment only — the final decision must follow the manufacturer’s datasheet and the applicable NEC / IEC / UL standards. Results are calculated from the standard formulas stated on this page and are for design estimates only. They are not a rating of any specific part — always confirm current, voltage, temperature and environment limits against the manufacturer’s datasheet for the part you intend to use.
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