Selection Guide
How to Select a Supercapacitor: A Step-by-Step Engineering Guide
A practical workflow for selecting a supercapacitor: define the load, size capacitance and voltage, check ESR, temperature, lifetime, and form factor.
Updated 2026-10-28 · 9 min read
The challenge
Supercapacitor datasheets list dozens of parameters, but a successful selection depends on only a few — and on how they interact under your real load profile. Selecting by capacitance alone is the most common reason a design fails validation.
Step 1 — Describe the load
- Load type: constant current, constant power, or pulses
- Peak current and duration
- Required hold-up or support time
- Minimum voltage at which the load (or converter) still works
- Charge source and available charge time
Step 2 — Calculate required capacitance
C = 2·E / (V1² − V2²)
For a constant-current load, use C = I·t / (V1 − V2). For constant-power loads (common behind DC/DC converters), use energy: C = 2·P·t / (η·(V1² − V2²)). Then add margin for capacitance tolerance and end-of-life degradation.
Step 3 — Choose voltage and cell count
Pick a working voltage at or below the rated voltage, with derating if long life or high temperature is expected. If the bus exceeds one cell’s rating, series cells are needed with balancing.
Step 4 — Check ESR
The instantaneous drop ΔV = I·ESR happens before any capacitive discharge. At high currents ESR can consume much of your voltage window — and it rises at low temperature.
Step 5 — Temperature and lifetime
Lifetime is governed mainly by voltage and temperature. A widely used rule of thumb is that life roughly halves for every 10 °C increase, and is also extended by voltage derating. Use the manufacturer’s life curves for your specific part.
Step 6 — Form factor and mounting
Format
Typical range
Best for
Coin cell
0.01–1.5 F
RTC / memory hold-up, µA loads
Radial lead
~0.5–100 F
PCB backup, pulse buffering
Snap-in
~100–500 F
Higher current on PCBs
Screw / weld
~300–3000+ F
Modules, power assist
Module
System voltage
16 V – hundreds of V buses
Need help applying this?
Send your load profile and our engineers will suggest suitable parts.
Practical considerations
- Inrush current when charging from 0 Vlses
- Leakage current in long-standby designs
- Polarity marking — supercapacitors are polarised
- Safe discharge before handling large cells
Recommended supercapacitor types
Winding-Type Supercapacitors
Cylindrical cells built from wound electrode foils — the workhorse format from a few farads to thousands.
Explore
Radial-Lead Supercapacitors
Through-hole cylindrical cells for PCB mounting, typically from about 0.5 F to around 100 F.
Explore
Supercapacitor Modules
Series/parallel assemblies with balancing, housed for system-level voltage and energy.