How to Install a Battery Isolator

by David Sandoval

Too many electronics connected to an automotive electrical system can stress the battery. Some car owners choose to install an auxiliary battery to operate these electronic devices. An auxiliary battery may prove to be a drain on the main battery if the auxiliary battery is connected improperly. One way to charge both batteries without imposing a strain on the electrical system is to install a battery isolator.

Loosen and remove the retaining nut on the alternator "BAT" terminal. Remove the cable from the "BAT" terminal.

Loosen and remove the retaining nut on the isolator "1" terminal. Place the cable that you removed from the alternator "BAT" terminal and install it to the "1" terminal on the isolator. Replace and tighten the bolt on the "1" terminal so that it holds the cable snugly.

Loosen and remove the retaining nut from the isolator "A" terminal. Install one end of the alternator-to-isolator cable to the isolator "A" terminal. Reinstall and tighten the "A" terminal retaining nut.

Install the loose end of the alternator-to-isolator cable to the "BAT" terminal on the alternator. Replace and tighten the "BAT" terminal retaining nut.

Install the spare battery. Drill a hole in the automobile frame near the spare battery and place the brass bolt through the hole. Place one end of the spare battery cable over the bolt. Install and tighten the brass nut to the bolt so that the nut holds the cable firmly to the bolt.

Loosen and remove the retaining nut from the isolator "2" terminal. Install one end of the battery-to-isolator cable to the isolator "2" terminal. Reinstall and tighten the "2" terminal retaining nut.

Install the loose end of the battery-to-isolator cable to the positive terminal on the spare battery. Install the loose end of the spare negative battery cable to the negative terminal on the spare battery.

Items you will need

About the Author

David Sandoval has served as a trainer and technical writer since 2000. He has written several articles online in the fields of home improvement, finance, electronics and science. Sandoval has an Associate of Applied Science in microelectronics from Northern New Mexico College.

Photo Credits

  • photo_camera closeup of jumper cables image by Katrina Miller from Fotolia.com