1969 Mercury 350 (35hp) – Charging circuit and lithium ion battery issues

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  • March 21, 2022 at 10:40 am #256572
    ChrisAF
    Participant

      Hello everyone. I was hoping that someone could tell me whether or not my outboard has a charging cicruit. This question is related to some troubleshooting I have been doing to figure out why my lithium ion battery occassionally shuts of when the outboard is running. I understand that there can be issues with lithium ion batteries and charging from older outboards with stators. With that said, I’m hoping someone can definitively tell me whether or not my outboard has a charging circuit.

      I posted this on a separate forum with many more details here: https://www.thehulltruth.com/marine-electronics-forum/1212609-ionic-lithium-battery-randomly-shuts-off.html

      I also created this video of the outboard in question: https://youtu.be/Tsr4YwTGG70

      My final question is: will I cause any damage to the outboard if I disconnect it from the battery while it is running? I am considering installing a cuttoff switch to disconnect the outboard from the battery after starting to isolate the battery from any weird voltage fluctuations from the outboard.

       

      Thanks in advance!

      March 21, 2022 at 11:27 am #256575
      crosbyman
      Participant

        Canada Member

        well if the battery  shuts off  ….see if you can measure the  batt.  12v post voltage  when you start  to increase  rpms  and the moment the battery reacts

        if the voltage goes up you likely have  charge cct  and your battery may have one of those fancy EMS    battery monitor… how else would a battery shut down !

        My Merc 50  was bad that way  causing shut  downs my  depth sounder because of  unregulated  charge volage ….. not tolerable voltage… by my depth sounder anyway .

        in your case the battery shuts down so look  (measure what  comes back from the engine when the shut down happens)

        have you tried swapping batteries (in case the start battery has a defect)   and  leaving the troller   side   batt. out of the connection.

        Joining AOMCI has priviledges 🙂

        March 21, 2022 at 11:28 am #256576
        crosbyman
        Participant

          Canada Member

          well if the battery  shuts off  ….see if you can measure the  batt.  12v post voltage  when you start  to increase  rpms  and the moment the battery reacts

          if the voltage goes up you likely have  charge cct  and your battery may have one of those fancy BMS    battery monitor… how else would a battery shut down !

          My Merc 50  was bad that way  causing shut  downs my  depth sounder because of  unregulated  charge voltage ….. not tolerable voltage… by my depth sounder anyway .

          in your case the battery shuts down so look  (measure what  comes back from the engine when the shut down happens)

          have you tried swapping batteries (in case the start battery has a defect)   and  leaving the troller   side   batt. out of the connection.

          Joining AOMCI has priviledges 🙂

          • This reply was modified 3 years, 2 months ago by crosbyman.
          March 21, 2022 at 12:06 pm #256577
          ChrisAF
          Participant

            Unfortunately I was unable to replicate the problem when I was troubleshooting with the boat out of the water. Yes, the battery does have a battery management system that will shutoff the battery if any of the parameters exceed certain thresholds. When troubleshooting, I did disconnect the outboard from the battery and tested the voltage coming from the outboard when running.  I could only read an alternating current voltage of 0.2V. It did not change significantly when reving the outboard. There is a possibility that my multimeter is faulty or could not pick up higher frequency voltage fluctuations. I’m going to purchase a new multimeter today and test again.

            Bottom line, I am hoping to find someone with knowledge about this specific outboard to tell me if it does or does not have a charging circuit. And also if disconnecting it from the battery while running will do any damage.

            March 21, 2022 at 12:10 pm #256578
            crosbyman
            Participant

              Canada Member

              checked my books but it starts at 40HP  +

               

              … maybe  these batteries  are not appropriate for  simultaneous starting/accessory duties . starting current is very high and may trigger BMS  protection

              Lithium Battery Management Systems and Battery Protection | RELiON (relionbattery.com)

               

              se e wiring on your 2cyl merc 350

              no need to buy a meter ….. no  charging from this one !

              PrecisionScan (maxrules.com)

              Joining AOMCI has priviledges 🙂

              • This reply was modified 3 years, 2 months ago by crosbyman.
              March 21, 2022 at 1:25 pm #256581
              ChrisAF
              Participant

                Thanks! That is the same diagram I found in my manual. I posted that in the other forum (linked in my OP) yet others responding there refused to believe it didnt have a charging circuit.

                So, it must be the induced voltage in the primary power cables that is tripping the battery to shut off. I did in fact measure a voltage there, so I know it exists (although very small at 0.2V AC. )

                I’ll go ahead with my plan to install a cutoff switch.

                Also, I know it is not the current draw from the starter that is shutting down the battery. Battery has a peak continuous discharge of 100A and 500A for 3 seconds. I also confirmed this by calling the manufacturer. Also, the battery never shutoff when starting, it only did so when idling around at 3mph (many minutes after starting). If it were the current draw from starting, the battery would switch off immediately.

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