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Adding second battery to car via accessory fuse

  • 22-11-2021 10:58pm
    #1
    Aaron-oc
    Registered Users, Registered Users 2 Posts: 5 ✭


    I am adding a second battery to the boot of my car to run my dashcam in parking mode for extended periods. I had a 12v 14ah SLA battery lying around so decided to simply tap into an accessory fuse and hook this right up. The battery charges when the car is running and stops when car is off, providing constant supply to the dashcam, until a cutoff voltage of 12.2v is reached.

    Question is, is this safe? I hear of people using a battery isolater in between, but I don't think it's necessary.

    I have a solar controller lying around, perhaps I should add this in-between. The 'solar input' side can come from the accessory fuse, and hook the battery side up to my 14ah battery. is this safer or not at all necessary?

    Cheers!



Comments

  • #2
    whizbang
    Registered Users, Registered Users 2 Posts: 1,974 ✭✭✭whizbang


    Your problem will come when your SLA battery has discharged down to a low level. The alternator/Car battery combination will pump as much current as it can to get the voltage back up. This hopefully will just blow a fuse, rather than blow the cables or battery..!

    You dont need an 'Isolator' - just have someway you can disconnect the battery quickly.

    Solar controller sounds like a plan - it should limit the charge current, and if it has a lo voltage load cutoff, your golden.



  • #3
    whizbang
    Registered Users, Registered Users 2 Posts: 1,974 ✭✭✭whizbang


    Woops, Sorry just noticed the op date....



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