Calculator Form
Formula Used
Cell capacitance: Ccell is converted to farads.
Bank capacitance: Cbank = Ccell × parallel strings ÷ series cells.
Bank voltage: Vbank = Vcell × series cells.
Bank ESR: ESRbank = ESRcell × series cells ÷ parallel strings.
Stored energy: E = 0.5 × C × V².
Usable energy: Eusable = 0.5 × C × (Vstart² - Vend²).
Delivered energy: Edelivered = Eusable × efficiency.
Constant current runtime: t = C × (Vstart - Vend) ÷ I.
Constant power runtime: t = Eusable ÷ input drain power.
Voltage sag: Vsag = I × ESRbank.
How to Use This Calculator
- Enter the rated capacitance for one supercapacitor cell.
- Select the capacitance unit used by the datasheet.
- Enter rated, starting, and ending voltage per cell.
- Add the number of series cells and parallel strings.
- Enter ESR and leakage current from the datasheet.
- Choose constant power or constant current load mode.
- Add efficiency, derating, runtime, and energy targets.
- Press Calculate to view energy, runtime, and safety checks.
- Use CSV or PDF buttons to save the result.
Example Data Table
| Use Case | Cell Capacitance | Series | Parallel | Start V/Cell | End V/Cell | Load |
|---|---|---|---|---|---|---|
| Short backup module | 3000 F | 6 | 2 | 2.5 V | 1.35 V | 100 W |
| Pulse power bank | 500 F | 10 | 4 | 2.4 V | 1.2 V | 30 A |
| Ride through supply | 1200 F | 8 | 1 | 2.45 V | 1.5 V | 60 W |
Supercapacitor Energy Storage Guide
Supercapacitor Energy Storage Guide
Supercapacitors store electrical energy in an electrostatic field. They charge fast and deliver high current. They are useful for short backup, pulse power, ride through support, and regenerative capture. This calculator estimates the energy stored in a cell or a complete bank.
Why Bank Design Matters
A single cell has a low voltage rating. Designers often place cells in series to raise bank voltage. Series wiring lowers effective capacitance. Parallel strings raise capacitance and current capability. Both choices change energy, ESR, leakage, and safe operating limits. The tool combines these effects so the result matches the complete assembly.
Usable Energy
The total stored energy is not always usable. Many loads stop working below a minimum voltage. The calculator uses the starting and ending voltage to find usable joules and watt hours. It also applies converter efficiency. This gives a practical estimate for energy delivered to the load.
Runtime and Losses
Runtime depends on load type. Constant current loads draw a steady current as voltage falls. Constant power loads draw more current when voltage is lower. The calculator supports both modes. ESR loss and leakage are also estimated. These values help you judge heating, voltage sag, and standby drain.
Safety and Derating
Supercapacitor cells should not exceed rated voltage. A derating target gives extra room for tolerance, temperature, and balancing error. The calculator compares bank voltage with the safe operating limit. It also reports possible short circuit current from ESR. This value is only an estimate, but it shows why fusing and controlled charging matter.
Practical Use
Use realistic voltage limits from your load and converter. Enter measured ESR when possible. Include leakage current from the datasheet. For series banks, use balancing circuits where needed. Review energy, runtime, current, and derating together. A good design has enough energy, acceptable losses, and safe voltage margin.
Check the output against real testing before building hardware. Supercapacitors have wide tolerances. Temperature can change capacity, ESR, and leakage. Aging can also reduce performance. For critical systems, add monitoring, overvoltage protection, and controlled discharge paths. Choose wires, switches, and connectors for the maximum fault current. Keep records of assumptions so future maintenance remains simple. Always follow component datasheets and local electrical rules.
FAQs
What does this calculator measure?
It measures stored energy, usable energy, runtime, bank capacitance, ESR loss, leakage, derating margin, and required capacitance for a target runtime or delivered energy.
Why is usable energy lower than stored energy?
Loads cannot always use the full voltage range. When voltage falls below the minimum input level, remaining energy may stay unused unless a converter can still operate.
Why does series wiring reduce capacitance?
Series cells share voltage, but their equivalent capacitance decreases. The bank capacitance equals one cell capacitance divided by the number of series cells, then multiplied by parallel strings.
Why does parallel wiring increase capacitance?
Parallel strings add storage capacity. They also reduce equivalent ESR and improve current capability, but leakage current can increase with more parallel paths.
What is ESR in a supercapacitor bank?
ESR is equivalent series resistance. It causes voltage sag and heat during high current discharge. Lower ESR usually improves pulse performance and runtime accuracy.
Should I use constant power or constant current mode?
Use constant power for converters and electronic loads that regulate output power. Use constant current for loads that draw nearly steady current as voltage changes.
What does derating mean here?
Derating means operating below maximum rated voltage. It gives margin for tolerance, balancing error, temperature, aging, and transient charging conditions.
Can this replace real testing?
No. It gives design estimates. Always verify with datasheets, thermal checks, protection circuits, balancing circuits, and controlled tests before using a bank in real equipment.