Battery isolator for 2nd battery

Discussion in 'Audio, Video & Gadget Tech' started by Padre, Oct 19, 2009.

  1. Padre

    Padre Rockstar

    Hi all, I've put a 2nd battery in my 2009 Silverado 2500hd. I have made a rough Paint drawing of how I intend to wire the isolator. Please tell me if I am doing it right??!!! Thanks!

  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The way you have this now is not correct IMO. Most isolator set ups run the charge wire from the isolator to the alternator. This way either battery gets charged while only one can discharge at a time.

    Here's a link to a PDF.

    Click Here
  3. Padre

    Padre Rockstar

    Thank you for that info, but it confuses me a little. The diagram on page 2 under number 9 shows 3 batteries. One using the isolator, and one using a simple in line hook up of positive to positive, negative to negative.
  4. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You want to use the GM diagram on page 1.
  5. Padre

    Padre Rockstar

    Jimmiee.....I'm still confused, and rack that up to my being inexperienced in this.:neutral:

    On this application guide from Sure Power, it says that most 1993 and up GM vehicles use the "CS" alternator. That means using the diagram on page 3? How can I tell if my alternator (160 amp) is this "CS" type?

    Thank you!
  6. Padre

    Padre Rockstar

    And one last question (I hope!): Do I need an isolator at all or can I just run positive to positive?
  7. TheUnit

    TheUnit Rockstar

    have you considered a Perko battery switcher rather than the isolator? Much less headache.
  8. Springthing

    Springthing Epic Member 5+ Years 1000 Posts

    Battery switcher is a totally different animal I believe.

    Padre- you CAN just hook up the batteries (I have in mine - isolator coming on Monday, actually... finally getting around to it!) but you run the risk of having two dead batteries.

    As Jimmie said you will want the simple isolator where, following from the alternator, power goes from the alt to the isolator then two out from the isolator to both (+) terminals of your batteries.

    In essence what you are trying to achieve is the batteries being able to take a charge but both have a different power drain. The isolator let's power flow one way (to the batteries) but not in the opposite direction (from one battery to a potentially bad/dead battery)
  9. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You can tell the difference by looking at the connectors. The chart shows both configurations. Springthing answers your other question about not using an isolator. Have fun!
  10. TheUnit

    TheUnit Rockstar

    I haven't seen a specific need for an isolator - so a switcher would be an easier alternative that offers the same functions. BATT1..BOTH..BATT2..OFF. As long as you trust your alternator not to spike, an isolator is a waste.

    I've installed tons of these in vehicles and never encountered any negative effects. Switchers were originally designed for marine applications, but over the years more 12V A/V specialists began using them. Personally, I've used three in personal rides and would never go back to isolators.
    Last edited: Oct 25, 2009

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