1974 Johnson 70 over charging to 15.3 volts

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  • January 23, 2023 at 10:46 am #271629
    Txgunslinger
    Participant

      Well I spoke to CDI and like some of you said he wouldn’t really worried about 15.3 V. But if it was concerning they had a regulated rectifier that would hold it down somewhere around 14 14 1/2 V. So that’s what I did I order the CDI regulated rectifier.

      This seems foreign to me because I’ve had boats all my life and I could always look at the voltmeter on my Suzuki’s, or my mercury. Verrado’s end they’ve always held a voltage about 13.2 volts . I guess that’s the difference between old old motors, and the new motors that are being produced in the last 20 years. Thank you all for your replies.

      January 23, 2023 at 12:15 pm #271633
      crosbyman
      Participant

        Canada Member

        happy ending 🙂

        Joining AOMCI has priviledges 🙂

        January 23, 2023 at 5:09 pm #271649
        billw
        Participant

          US Member

          13.8 used to be sort of the accepted “ideal,” but these days, I see 14 to 14.5 on new engines all the time. I personally don’t like 15 and above, either. If I had a boat with that reading, I would be trying to find out why.

          Long live American manufacturing!

          January 23, 2023 at 5:29 pm #271657
          Txgunslinger
          Participant

            Yeah the 15.3 kind of freaked me out a bit. I replaced all the electrical components and the wife wanted to go boating so we went and dropped it in the water and everything was “normal “ until I looked down and saw 15.3 on my volt meter and then checked my garmin 740s and it verified the voltage. I’ll install the regulator/rectifier this evening and check the timing and then give it a try.

            Update; Worked like a charm.

            • This reply was modified 2 years, 5 months ago by Txgunslinger.
            January 24, 2023 at 5:16 pm #271681
            billw
            Participant

              US Member

              Funny, usually the Garmins on our boats under-rate the actual voltage entering the unit by 1/2 to one full volt. It makes for some semi-hetaed discussions between the electronics techs and the engine techs at the boatyard. Like, say there is 12.5 at the back of the unit. The display might say 11.5, which leads the electronics guys to tell us a reported electronics problem is a problem with the boat, not the electronics……

              Long live American manufacturing!

              January 24, 2023 at 8:49 pm #271687
              fleetwin
              Participant

                US Member

                Overcharging on non regulated OMC charging systems is not uncommon, doesn’t mean it is an acceptable situation though.  The battery and electronics could be damaged, I remember having one customer who’s battery boiled out most of the fluid and more or less “exploded”.  Battery condition, perhaps being undersized can aggravate this condition as well.  Poor battery connections can have the same effect.    These are only 6amp systems, hard to believe batteries can get “overcharged”, but they do.

                OMC does/did make a crude regulator for these systems, but it only cuts out half the output.  Kit 173640, NLA though, perhaps it can be found though.  But, it sounds like CDI has helped you out with their version.

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