Tips on How to Wire a Capacitor

A car accessory like a stereo ​can strain your electrical system. If you find ​other accessories are having a hard time getting the ​required power, or other car accessories like the headlights are dimming or blinking, then it is time to install a capacitor.

A capacitor ​serves as a power storage device to provide ​additional electricity to ​your vehicle. You can let ​a ​mechanic install the capacitor, or you can do it on your own as the process is easy. Before you learn how to wire a capacitor, you need to find the right capacitor first.


The capacitor serves as a storage tank for electrical power. The power capacity of a capacitor is measured in Farads, and generally you need one Farad of capacitance for every 1 kilowatt of power needed by your system.​

There are some capacitors that are equipped with meters that show their present charge. If you choose this route, wiring the meter into a switched power supply is required so the meter will turn off together with the car. ​Otherwise, the meter will continue to run and it will drain your system.

How to Wire a Capacitor?

How to Install a Capacitor to Your Car

What You Need:

  • Power Capacitor
  • 1 Farad

    1.5 Farad

    10 Farad

    2 Farad

    20 Farad

    3 – 4.9 Farad

    30 Farad

    5 Farad

    6 Farad

    8 Farad

  • Eight Gauge Wire
  • Hand Tools
  • Resistor
  • Voltmeter
  • Wiring Tools

The capacitor should be discharged first. A charged capacitor can easily release an enormous amount of energy. This is dangerous. It is important that you handle electrical components the right way.

Step 1

Disengage the battery ground terminal to make sure there is no electric running.

In case you already have a capacitor connected in your system, you need to discharge it. It stores power, and therefore can still cause shock even if you remove the power supply.

Mount the capacitor. You can place the capacitor in different areas in your system. There is only a small difference in performance no matter where you position it, but it is best if you place it in the area nearest to the components that require power. Make sure that you place it in an area where there is a suitable place to mount it, away from passengers.

wire a capacitor

Step 2

Keep in mind that you will install the capacitor to provide additional power to accessories like upgraded stereo systems. It is like a storage tank for power that supplies the entire system. If you position it near the parts that are not getting enough power, you will enable it to supply power to those parts with less loss than the additional resistance of a long wire.

Connect the positive terminal of the capacitor. It does not matter if you are connecting it to the amp, distribution block of some kind, or the battery. You need to attach the positive terminal of the capacitor to the positive terminal of the other component by putting a wire between them. It is recommended that you use eight gauge wires.

Step 3

Attach the negative terminal of the capacitor. Connect this terminal to the ground.

Attach the remote turn-on wire. If you choose a capacitor with an internal meter, it will have a third ​remote turn-on wire ​that acts to kill power to the meter when the car is turned off. Wire it into the remote turn-on wire in any 12-volt switched power supply (like the amplifier or ignition switch).

Connect the battery ground terminal again. This will bring back the power to your system. All of the components should be operational now.

Helpful Tips

If the electrical problem continues even with the addition of the extra power from a capacitor, you need to upgrade your car’s alternator.

Safety is important when working with a charged capacitor. Use goggles or safety glasses and remove any jewelry you are wearing before installing the capacitor.

Most of the capacitor encompasses a safety circuit which lights up when the connections are not right. If the light turns on, disengage the capacitor and check your connections.

Keep These Things in Mind

When charging or discharging a capacitor, never hold a resistor. It might get very hot, and if you ​have a small resistor, it might blow up.

Make sure that the capacitor is charged before installing. This will serve ​instant power to the system and can blow any fuse in the system. It is important that you charge the capacitor first.

Before disconnecting, discharge the capacitor from the circuit. You can do this by connecting the resistor across the capacitor’s leads.

Now You Too Can Wire A Capacitor!

Some of your car accessories may not function well and require additional power to work properly. It is important that you choose the right capacitor to supply enough power to accessories like the sound system. You don’t need the biggest capacitor on the market. To determine the capacitor’s size and the number that your sound system requires, calculate the amplifier’s wattage and convert it into Farads.

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