How to Charge a Car Audio Capacitor

An automotive audio capacitor resembles a large aerosol can.

Audio systems in most automobiles require less power than the automotive charging system is capable of generating. However, audio systems which draw more than 100 watts per channel may siphon power from other accessories, such as headlights, when these systems are operated at night. One way to keep an audio system from siphoning power from other devices is to use a large (500 mF to 1F) audio capacitor. Wiring this capacitor in a parallel circuit with the battery will charge the capacitor and smooth out any power fluctuations an audio system may cause.

Things You'll Need

• Automotive battery
• Replacement battery terminal connectors
• Adjustable wrench
• Automotive audio system
• Automotive audio capacitor (between 500 mFand 1F capacitance value)
• Automotive electrical wire
• Electrical pliers
• Four ring terminals
• Soldering iron
• Rosin core solder

Instructions

1. Using an adjustable wrench, disconnect the battery terminal connectors from the battery. Snip the positive battery terminal connector off the battery cable and strip 1/2-inch of insulation from the battery cable.

2. Cut two pieces of electrical wire and strip 1/2-inch of insulation from the ends of each wire. Twist together one end of the first wire with the stripped end of the positive battery cable.

3. Loosen the top bolts of the first replacement battery terminal connector, and insert the twisted wire pair into the space created by loosening the top bolts. Tighten the terminal connector top bolts until the battery cable twisted wire pair is snug and solder the cable to the terminal connector.

4. Snip the negative battery terminal connector off the battery cable, and strip 1/2-inch of insulation from the battery cable. Twist together one end of the second wire with the stripped end of the negative battery cable.

5. Loosen the top bolts of the remaining replacement battery terminal connector and insert the twisted wire pair into the space created by loosening the top bolts. Tighten the terminal connector top bolts until the battery cable twisted wire pair is snug and solder the cable to the terminal connector.

6. Slip a ring terminal over the free end of the first wire and solder the terminal to the wire. Unscrew the positive terminal retaining cover nut from the capacitor and place the ring terminal over the threaded capacitor positive terminal connector.

7. Slip a ring terminal over the free end of the second wire and solder the terminal to the wire. Unscrew the negative terminal retaining cover nut from the capacitor and place the ring terminal over the threaded capacitor negative terminal connector.

8. Strip 1/2-inch of insulation from the audio system "power" wire and slip a ring terminal over the wire. Solder the terminal to the wire and place the ring terminal over the threaded capacitor positive terminal connector. Replace the positive terminal retaining cover nut. Tighten the nut so the ring terminals do not move.

9. Strip 1/2-inch of insulation from the audio system "ground" wire, and slip the remaining ring terminal over the wire. Solder the terminal to the wire, and place the ring terminal over the threaded capacitor negative terminal connector. Replace the negative terminal retaining cover nut. Tighten the nut so the ring terminals do not move.

10. Reconnect the battery terminal connectors to the battery. Tighten each connector's retaining nut.

References

• University of Waterloo (Canada): Capacitor Theory
• "Electricity, Magnetism, and Light"; Wayne M. Saslow; 2002
• Battery Maintenance; Popular Mechanics; August 2000