Charging circuit

seahawkseahawk Kingston,Ontario, CAMember Posts: 28
What is the practical difference between an Automatic Charging Relay and a Battery Isolator. Are there advantages to one over the other. I understand that there is a more significant voltage drop across an isolator but not so much with the ACR.  What else is there to think about when considering one vs the other..???      Thanx for the input.      


  • LaReaLaRea Alexandria VirginiaMember Posts: 5,174 ✭✭✭✭✭
    Right - the main thing is that the ACR eliminates the voltage drop that you get with a normal diode isolator.  But an ACR is not as good as a digitally controlled isolator such as the ProIsoCharge.  An ACR just combines batteries during charging.  If your house battery is low but the starter is fully charged, the ProIsoCharge will actually disconnect from the starter to charge the house more efficiently.  
  • seahawkseahawk Kingston,Ontario, CAMember Posts: 28
    Thanx LaRea...I was under the impression that an ACR also electrically disconnected the Start and House batts,  in the event of the house batts being low,  so that load requirements  wouldnt drain the Start.

    I thought it sensed a charging situation when the batts were charging with either Shorepower or alternator, and allowed both batts to be charged but subsequently sensed when the batts were being discharged and isolated the Start batt to protect it....which ( if I understand you ) is exactly what the isolator does.
    Thats why I thought the ACR was kind of "magic" if it did the same thing with no voltage drop. Youre telling me theres no such thing as 'magic"....??....  :-)
  • LaReaLaRea Alexandria VirginiaMember Posts: 5,174 ✭✭✭✭✭
    edited February 21
    The ACR is just a computer-controlled relay.  When the source voltage gets high enough, the relay closes, connecting the batteries to each other.  When there's no charging voltage, the relay stays open and the batteries stay isolated from each other.  

    The other thing the ProIsoCharge does is prioritize the starter battery.  

    I can't think of a reason to use an ACR rather than a ProIsoCharge.  The ACR costs a little less, but not a huge amount.  
  • seahawkseahawk Kingston,Ontario, CAMember Posts: 28
    Well I think that pretty well answers my question. I appreciate your responses. The isolator seems like the way to go.  Is the Pro Isocharge a DIY job..??...or is it more complicated..?

  • YYZRCYYZRC Georgian BayMember Posts: 1,538 ✭✭✭
    edited February 21
    Pretty easy DIY. Plug and play except that you need to run a wire to the ignition switch and you will need to drill out or replace the ring terminals. 

    2008 330 EC on Georgian Bay
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