Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Leakage time constant (h)

RC leakage time constant of the supercapacitor in hours.

Charged voltage (V)

Fully charged voltage at the start of storage.

Acceptable voltage (V)

Lowest voltage the application still accepts.

Estimate how long a supercapacitor takes to self-discharge from a charged voltage down to an acceptable voltage. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Self-discharge time (days)

Estimated days until the voltage decays to acceptable.

• Supercapacitor energy and self-discharge models depend on capacitance tolerance, ESR, leakage that changes with voltage and time, balancing, temperature, aging, and safe cell voltage. A single RC model may poorly represent long-duration behavior.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

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  Compute the capacitance required to hold up a load from the input voltage down to a minimum voltage for a given time at constant power.