Capacitor Energy Storage Calculator (J)

Every capacitor stores energy proportional to capacitance and to voltage squared - doubling voltage quadruples the reserve. This calculator converts farads and volts into joules and watt-hours so different storage technologies compare fairly. Example: a 2200 uF DC-link capacitor at 400 V holds 176 J; delivering 500 W during a 0.1 s mains dip requires exactly 50 J, so one capacitor rides through ten cycles with margin. Banks add cell energies linearly whether series or parallel. Voltage window economics: because E scales with V squared, doubling bank voltage quadruples stored energy in the same capacitance, which is why EV DC links run at 400-800 V rather than 48 V.

1. 1

   Enter capacitance

   In F, uF, or nF.

2. 2

   Enter working voltage

   Charged volts.

3. 3

   Read energy

   Joules, Wh, and pulse capability.

• Using peak instead of working voltage and overstating energy

• Forgetting the usable window: you can only spend energy above the minimum operating voltage

• Ignoring ESR losses that heat the capacitor on fast discharge