How to Install a Second Battery

A marine dual battery system allows you to isolate your second battery from the primary one. Using the proper battery isolator will eliminate accidental discharge of your starter battery which could leave you stranded. It intelligently charges both batteries in sequence of importance from your existing engine or charge source.

Here are the basic steps.

Locate a convenient place for your second battery and use the dual battery kit to install. Mount the second battery close to the first battery if possible and secure it with either brackets or straps. After you have your location selected the dual battery kit will intelligently connect the batteries for charging purposes following these easy steps.

Disconnect the negative or black lead from the primary battery for safety. Determine a good location for the R140 Isolator. Generally a side or dividing wall near the first battery is preferred. Now measure from the primary battery’s positive terminal to the location where the isolator will be mounted to determine how much of the red cable included with the kit you will need to connect the two. Cut to length. Apply one of the two smaller crimp connectors to the cable end using a pair of crimp pliers. Open the back of the isolator and connect the new red cable to the red stud on the isolator. Remove the appropriate “knock out” on the side of the isolator to allow easy routing of the cable. Do not connect the new cable to the primary battery until the installation is complete.

Now measure to determine the length of red cable you will need to route from the R140 Isolator to the positive terminal of the second battery. Cut this length from the opposite end of the dual battery kit supplied coil of red cable to make use of the pre-installed connector. Strip the cable end and apply the second small crimp connector and connect this cable to the remaining terminal on the back of the R140 dual battery isolator. Remove the “knock out” to allow proper routing of the cable to the second battery. Replace the back cover of the isolator making sure both red cables are routed through the knock outs as well as the attached black ground wire.

Fasten the R140 battery isolator to the predetermined spot with the supplied screws. Now the small black ground wire from the isolator should be connected to a common ground shared by both batteries.

Using the short black cable insure that both batteries are connected with a common ground. This can be accomplished by connected the negative terminals to each other or a common conductive source such as a metal or aluminum wall in the boat. The small black negative wire from the R140 battery isolator should be connected to the same. Then use the dual battery kit supplied zip ties to secure the cables accordingly.

Finally connect the appropriate ends of the red cable to the primary and secondary batteries. Reconnect all negative or black leads back to original terminals. Make a final check that all is secure and you have complete the installation of a second battery with the dual battery kit.


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