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2nd Battery, Wiring Idea.

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  • 2nd Battery, Wiring Idea.

    Hello all. I believe this is my first post, though I have been reading on this forum for many months. I have an idea for a second battery hook-up and I was just looking for some input.

    My plan is to have a second 12v battery dedicated to the carputer. Between the car battery and the carputer battery I would have a relay (closes contacts with ACC power) as well as a diode (or several in parallel). The relay would allow the carputer battery to charge while the car is running, while the diode would prevent any possible drain on the carputer battery from the car. The plan is that worst case scenario the carputer only drains its own battery (if in standby) not the car battery.

    Does this make any sense? Any input would be much appreciated. Thank you.

  • #2
    go to a marine parts store and get what is called a battery isolator...
    it will allow the engine to charge the battery, but not allow the second battery to drain the main battery
    95 Mazda Protege LX
    Overall [Project Dead] 0%

    2003 Nissan Altima
    [XXXXXXXX--] 80% Planning



    • #3
      Hey I am thinking about doing the same thing also. I am not really sure what this battery isolator does and how it works, but I was thinking of just using a simple high current relay. The 2nd battery would be connected to the computer always, and a relay would connect the second battery with the vehicle battery when there is ACC power (engine is on). The relay would disconnect the 2nd battery from the vehicle battery once the engine is turned off, thereby isolating the computer electrical system from the car's electrical system.