By Tricia Lobo
Updated Mar 24, 2022

A capacitor is an electrical component consisting of two conductors separated by an insulating material. When a voltage is applied across the conductors, an electric field forms and the capacitor stores energy. While a battery continuously delivers charge, a capacitor holds charge until it is discharged and can be recharged when a voltage is reapplied.

Step 1 – Select a Compatible Battery

Choose a battery whose maximum voltage matches the capacitor’s rated voltage. Using a higher voltage risks damaging the capacitor.

Step 2 – Wire the Circuit

Connect one terminal of the battery holder to the normally open switch. The switch remains open when the device is in the up position, preventing accidental charging.

Step 3 – Add a Current‑Limiting Resistor

Attach a resistor to the other side of the switch. The resistor slows the charging current, protecting the capacitor from a surge.

Step 4 – Connect the Capacitor

Wire one side of the capacitor to the resistor and the other side to the battery holder. Ensure correct polarity if the capacitor is polarized.

Step 5 – Measure the Voltage

Hook the multimeter leads across the capacitor terminals and set the meter to read voltage. This will display the charging voltage as the capacitor charges.

Step 6 – Charge the Capacitor

Insert the battery into the holder and close the switch. Observe the voltage on the multimeter; the reading will rise until the capacitor reaches its rated voltage, indicating it is fully charged.

Things Needed

• Capacitor (rated for the desired voltage)
• Battery matching the capacitor’s voltage rating
• Switchable circuit wiring
• Switch (normally open)
• Multimeter capable of measuring voltage
• Resistor for current limiting

Warning

Unlike batteries, capacitors do not provide a continuous discharge. They store energy for a brief period and then release it quickly, after which they must be recharged. Handle all components with care and follow safety guidelines.