How do I size a supercapacitor bank?
Ns groups in series of Np cells in parallel give C = Ccell·Np/Ns and a rated voltage Ns·Vcell. The stored energy is E = ½·C·V², so the energy per cell is the same in every layout.
E = ½ · C · V²
Supercapacitor bank calculator
Enter the energy you need and one cell’s capacitance and voltage: the calculator gives the series/parallel layout, charging, ESR losses and balancing.
Supercapacitor bank
Examples: energy 500 or 2k (kJ) · capacitance 100 or 3000 (F) · ESR 15m = 15 mΩ · leakage 10u = 10 µA. Leave the bus voltage empty to compare layouts at full cell voltage.
Times: 90s · 5min · 2h
Bank configurations
| Layout | Cells | Bank C | Charge V | V per cell | Energy | Charge time | Bank ESR | Action |
|---|
Highlighted row: configuration shown above. Energy per cell is the same in every layout, so the cell count only grows when rounding up the parallel count.
Frequently asked questions
How long does a supercapacitor bank take to charge?
At constant current I from 0 V, t = C·V / I. The charger delivers its peak power I·V at the end of the charge.
Why do supercapacitors in series need balancing?
Cells have different capacitance and leakage, so their voltages drift apart in series. Passive resistors across each cell, or an active balancing circuit, keep every cell below its rated voltage.