Starboard volt meter reads 1 volt less, trying to diagnose.

Discussion in 'Electronics Q&A' started by Griff 4, Nov 13, 2019.

  1. Griff 4

    Griff 4 New Member

    6
    May 27, 2019
    Bayliner 325
    two 350 cubic inch 250 hp Mercruiser engines Bravo II
    Our boat is now 10 years old since new. In the past, both gauges read about the same. Typical readings were 14 volts at idle and 13 volts at 3500 rpm cruise. Anyone had this in the past? Any suggestions are appreciated. Griff
     
  2. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Have your batteries ever been replaced or checked in the 10 years you've owned the boat? It's where I would start diagnosing a voltage issue...
     
  3. Griff 4

    Griff 4 New Member

    6
    May 27, 2019
    Bayliner 325
    two 350 cubic inch 250 hp Mercruiser engines Bravo II
    Thanks, I have replaced all 3 of my batteries at a variety of times and as needed. Will test them now, but they seem alright and the starboard battery is only a few months old.
     
  4. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    Unless the port battery is exactly the same, and the same age you have your answer. When the engines are running you are looking at the voltage in each charging circuit. The voltage in the circuit is dictated by the performance of the alternator as well as the condition of the battery/batteries. In general new batteries will charge faster and require less current/voltage. Also voltage is dictated by the voltage regulators in each alternator and one may be a little more tired than the other. Finally unless you have an ammeter you aren't getting the full story. Do the batteries have different voltages when there is no charging? If so the health of the batteries is the question. Are the voltages different because one is charging (alt output plus battery condition) and the other not (battery condition only).

    I have completely new engine batteries and they show different voltages, just like the oil pressures and running temps.

    Unless its really wonky I would keep an eye on it for any changes and not stress about it.
     
  5. Griff 4

    Griff 4 New Member

    6
    May 27, 2019
    Bayliner 325
    two 350 cubic inch 250 hp Mercruiser engines Bravo II
    Thanks Henry. I did make a bunch of checks of voltage today at a variety of locations. Also swapped the dash volt gauges. You are probably correct about variables, and I will now keep running the boat and see how it does. Best regards, Griff.
     

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