How to Install an Audio Capacitor in a Car

by Justin Chacos

Installing a state of the art stereo system in your car enhances overall driving enjoyment. When quickly reproducing the deepest bass notes, the stereo system's amplifier draws a large amount of power from your car's electrical system. This draw drains the power available for other electrical components and may result in headlight or interior light dimming. Adding a car audio capacitor to the system will give the amplifier a power reserve to draw from instead of from other car electrical components, thus reducing the aforementioned dimming and providing a more immediate sound reproduction. It holds a charge until the amplifier needs it, then recharges itself after the amplifier is finished.

Charge the Capacitor

Connect the resistor between the power wire from a 12-volt source and the capacitor's positive post. The car's battery is a suitable source. The resistor should have a resistance of at least 500 ohms, preferably 1,000 ohms.

Attach a voltmeter to the capacitor by connecting the positive lead to the capacitor's positive post and negative lead to the negative post.

Complete the circuit by grounding the negative post of the capacitor. Disconnect the ground when the voltmeter reads 12.0 volts. The capacitor is now charged.

Install the Capacitor

Disconnect the negative cable from the car battery and set it aside so it will not contact the negative battery post at any point during capacitor installation.

Choose a location in close proximity to the car audio amplifier to mount the capacitor. For best results, the length of power wire required to connect the positive post on the capacitor to the power input on the amplifier should be no more than 18 inches.

Mount the capacitor using the accompanying bracket, hardware and a screwdriver. If the capacitor did not come with a bracket, fashion one with band clamps from the local hardware store.

Remove the caps on the capacitor's posts using an Allen key. Do not allow any object to contact both posts.

Connect a ground wire from the capacitor's negative post to a bare metal ground point on the car's chassis. To verify the suitability of the ground point, place one lead of an ohm meter on the intended ground point and the other on a known-good ground point on the chassis. A good ground point will show little resistance on the ohm meter.

Disconnect the power wire from the power input on the amplifier. Trim the wire to an appropriate length and connect it to the capacitor's positive post.

Install a new power wire between the capacitor's positive post and the amplifier's power input.

Install a new, 16-gauge remote wire between the capacitor's remote turn-on post and the amplifier's remote input, if the capacitor is so equipped.

Reconnect the negative cable to the car battery.


  • check Crimp ring terminals on the ends of the power and ground wires for easier wire management and greater aesthetics.
  • check If the capacitor came with specific instructions charging it, follow the manufacturer's instructions.


  • close Handle the charged capacitor carefully. It holds a 12-volt charge that may cause injury if carelessly handled.
  • close Never allow any bare object to contact both capacitor posts.

Items you will need

About the Author

Justin Chacos is a professional mechanic with experience on all vehicle types, from cars to boats to airplanes. He has been writing since 2006 and has been published in multiple maintenance manuals and journals. He holds a Master of Science from the University of Arkansas.

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