Isolating Batteries

Discussion in 'Marine Electrical / Electronics' started by Bill_N, Jul 2, 2018.

  1. Bill_N

    Bill_N Captain

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    I installed a Startguard on my JC in 2015 since my electronics were shutting down when starting the engine. The Startguard never solved the problem altogether since it wouldn’t work when the internal battery wasn’t fully charged and now it needs to be replaced.

    Instead, I’d like to have my batteries rewired so I have an isolated “house” battery that would power the switch panels and electronics and a starting battery. I’d still like the ability to combine batteries in the event one is run down. The system should have the ability to charge both batteries as needed.

    I currently have 2 8D batteries running through a 1-2 or both battery switch to the switch panel.

    What is the best way to execute this? Anyone have an easy to follow schematic?
     
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  2. Genius

    Genius Captain

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    Engine wiring/starter goes to one battery and the house cable goes to the other. Blue Seas makes a switch/ACR kit for this purpose. It also has an ignition cut out switch.
     
  3. captjohn

    captjohn Senior Member

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    I installed FET battery isolator's from Victron in my boat about 4 years ago, and have never had a problem since. It's really a very simple setup. Because it uses Field Effect devices, rather than standard diodes, the voltage drop across it is only about 0.02 volts, basically nothing. It's an all solid state device as well, no moving parts, unlike relay units. You can charge up to 3 batteries with them. A 2 battery unit runs around $90.
     
  4. Diesel Jerry

    Diesel Jerry Captain

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    Before we go tossing parts at this there are a few questions we should be asking. Is this a condition that just started or has this always been like this? What is the condition of the battery cables and are they the proper size? What size wire goes to your house panel and is it the proper size? What is the condition? Before you go redesigning your electrical system check the basics first. Connections, grounds,and such. I just solved this same issue on a boat this winter by running bigger wire to the house panel.

    aaaaaannnnnddddd the Jackass award for not completely reading the original post COMPLETELY goes to Diesel Jerry. Yes I would recommend the ACR Genius mentioned. You could go right to the Blue Sea website and you maybe able to download the installation manual that would give you a schematic.
     
    Last edited: Jul 2, 2018
  5. Bill_N

    Bill_N Captain

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    I'll take the jackass award for this one. I should've done this in 2015 instead of installing the POS Startguard.

    The battery cables and wiring are all in good shape and sized correctly.
     
  6. Kodiakan

    Kodiakan Senior Member

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    Blue Seas ACR is a great product. The "add a battery" unit might fit your needs. If you look at it and decide you don't feel like going to the hassle, you can wire all your "stuff" to battery 2 and the motor to battery 1. Start on one and use 2 when fishing etc. My last boat had stuff wired to batteries one and two and no matter how I started it something shut down. My current 1,2, both doesn't have that problem, unless I forget to switch to battery 1 when starting. Thats when I wish I had the ACR system.
    I'm editing this because in re-reading the post I think I make it seem easier to successfully manage a 1,2 both system than it actually is. After starting on 1 while running I switch to 2 or both, depending on how long I was fishing. Also, it works for me because at the end of the day I have an Iota charger wired in and a big yellow cord I plug in every night. An ACR system is far better for most folks I think.
     
    Last edited: Jul 4, 2018
  7. Hansel

    Hansel Member

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    Anybody want to buy my new in box startguard? Sounds to me like the ACR is the better way to go. When making up battery cables do you guys add solder to your lug/crimp connections or is hammer down tool good enough?
     
  8. Hansel

    Hansel Member

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    Thanks Fortier, I have one of those crimpers that you hit with a hammer (for the big lugs) I will look into picking up a "bolt cutter sized" crimper.
     
  9. seasar33

    seasar33 Member

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    Before you buy the Blue seas add a battery kit, check your alternator for it’s output. The add a batt kit is for alternators smaller than 120 amps if I recall. But basically you just need a higher rated charging relay if your alternator is more than 120 amps.
     
  10. Bill_N

    Bill_N Captain

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    Good point. I called Blue Seas and I will need a higher amp ACR Model 7622. The 5511E Battery switch will work for me.

    The Add a Battery kit is sized for smaller engines and outboards.
     
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