Capacitor informationMotor capacitor information FAQ
You will notice that most capacitors have numbers printed on their bodies to indicate their electrical characteristics (for example 20 uF) Smaller capacitors use a shorthand of three numbers showing the capacitance in uF (calculated as XY x 10z for the numbers XYZ) and the letter indicates the tolerance (J, K or M for +/1 5%, +/-10% and +/-20% respectively)
Additionally, the capacitor may show its working voltage and temperature as well as other relevant characteristics. Also some Manufacturers may print MF which just indicated Microfarads (uF)
Energy Storage
Conventional capacitors provide less than 360 joules per kilogram of energy density where a conventional alkaline battery has a density of 590 kJ/kg.
Motor Starters
Motor Starting capacitors are typically non-polarised electrolytic types, while running capacitors are conventional paper or plastic film dielectric types.
Hazards & Safety
Please be aware that capacitors can retain a charge long after the power is removed from a circuit; this charge can cause dangerous or even potentially fatal shocks or damage connected equipment. Service procedures for electronic devices will include instructions to discharge any remaining charge.
Using a Digital Volt Meter to test capacitance level
Most DVM’s have a capacitance measuring function, these operate by charging or discharging the capacitor with a known current and then measuring the rate/rise of the voltage. Digital volt meters measure the capacitance from nanofarads to microfarads. Ducati are one of the best manufacturers of capacitors