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  • DF115 voltage related question

    Hi all,

    Would like to ask for assistance please. I'm experiencing an issues with the reading of my outboard info (rpms, fuel rate, etc) into my NMEA network (based on components from Lowrance). Basically, everything is working fine, until I throttle the motor up to higher rpms (above 5,000). As soon as I do that, the reading disappears (like if I'd turn the motor off). Once I back the throttle down (say below 5,000 rpms) the reading comes back. If I play with the throttle I can pick up rpms's where the reading 'flickers' e.g. constantly comes on and off. When it happens the NMEA itself is working fine, e.g. I have reading from other NMEA sensors with no interruptions.

    My network has been double and triple checked and Lowrance-Suzuki interface has been replaced twice. Didn't help. I have also noticed that when this happens, the 'Alternator Voltage' parameter from the motor shows 15.1-15.2 Volts or maybe even more. And motor temperature was about 80 degrees Celsius. I have also been told (by Lowrance) that acceptable voltage level for NMEA (upper range) is around 14.2 volts.

    I guess it narrows the issue down to 2 possible reasons. 1st - if there is something wrong with the motor itself so it does not always send the right data to the port. I suspect however (please let me know if I'm wrong) that I'd probably have more issues than just loosing the diagnostics if this is the case. 2nd - power problem, e.g. if the power the motor sends to NMEA is too high.

    So may I please ask the experts:

    1) Do my assumptions above sound right and high voltage can cause that sort of issues
    2) Am I right in assuming that the Lowrance-Suzuki interface takes the power from the NMEA bus, not from the engine port itself
    3) Are there known cases when the alternator voltage depends on rpm's (and maybe motor temperature) - e.g. higher rpms causing higher voltage
    4) Is there a possible issue in the motor electric system and can it be rectified or adjusted?

    Many thanks

  • #2
    Most of the time there are low voltage problems but any voltage out of range can cause problems. Low voltage can cause a current increase and cause components to overheat. High voltage would cause a lower current draw but a high enough voltage can cause component failure. That is a general statement on power systems and the digital systems operate on a different principle; they use voltage variations to bias diodes and operate gates on transistors so over voltage could cause things to go haywire.

    I think the NMEA power comes from the network but I think there may be power on the interface too (or at least a ground) It has been a couple of months since I installed mine so i can't quite remember the pin assignments and I don't have my manual with me.

    Voltage from the alternator will vary with engine speed and temperature. At lower RPM's the voltage is lower and will increase with speed until you hit max output and it stays at that level. There is a voltage vs rpm graph for the alternator. In any case, I would think something is wrong because 15V is very high, I think mine runs around 14.2V or 14.4 voltages once I hit 1200 or 1500 RPM's.

    Your voltage is rectified in modern systems. It sounds like you may have a problem with your rectifier.

    Comment


    • #3
      Originally posted by gdubroc View Post
      Voltage from the alternator will vary with engine speed and temperature. At lower RPM's the voltage is lower and will increase with speed until you hit max output and it stays at that level. There is a voltage vs rpm graph for the alternator. In any case, I would think something is wrong because 15V is very high, I think mine runs around 14.2V or 14.4 voltages once I hit 1200 or 1500 RPM's.

      Your voltage is rectified in modern systems. It sounds like you may have a problem with your rectifier.
      Thank you. It is definitely around 15.2V around 5,500rpm/80 Celsius... A very lame question - is 'rectifier' a part of the motor - e.g. is it something my Suzuki dealer has to look at?

      Comment


      • #4
        I have owned three DF 140's all of them have run in the 15.0 v range. It seems high to me, but after checking with several Suzuki mechanic they say it's normal.

        I know in the auto's 13.8v used to be the normal high, but now most system run up around 14.2v.

        You can purcahse an external dc voltage regulator for you electronics that will control the voltage to a narrower range for around $100.

        JIm

        Comment


        • #5
          Originally posted by Kruzenvax View Post
          Thank you. It is definitely around 15.2V around 5,500rpm/80 Celsius... A very lame question - is 'rectifier' a part of the motor - e.g. is it something my Suzuki dealer has to look at?
          They should be able to check your rectifier. Jhydroman had some good suggestions too about buying and aftermarket unit plus he has seen voltages that high on other Zukes.

          Comment


          • #6
            Thanks a lot for that; may I please just ask (not doubting your info, just to ensure I'm interpreting this correctly) - do you think the 15V power is not a likely cause of my problem; or that I may not have it fixed by Suzuki because it is normal for them and have to get that voltage regulator?

            Sorry if my question does not look right; merely trying to understand my next steps...

            Thanks again

            Originally posted by jHydroman View Post
            I have owned three DF 140's all of them have run in the 15.0 v range. It seems high to me, but after checking with several Suzuki mechanic they say it's normal.

            I know in the auto's 13.8v used to be the normal high, but now most system run up around 14.2v.

            You can purcahse an external dc voltage regulator for you electronics that will control the voltage to a narrower range for around $100.

            JIm

            Comment


            • #7
              Thank you. I'll do both; have asked my previous question in order to be prepared if Suzuki tells me that 15V is normal...

              Originally posted by gdubroc View Post
              They should be able to check your rectifier. Jhydroman had some good suggestions too about buying and aftermarket unit plus he has seen voltages that high on other Zukes.

              Comment


              • #8
                If they say 15V+ is normal I would try to contact Lowrance to see if they think 15V will affect the interface. You could also buy and add a voltage regulator to your fuse box. I just search for "12 volt voltage regulator" and a bunch popped up, ranging from $10 to $100.

                Comment


                • #9
                  I also think your engine temp sounds a little bit high. Mine runs at about 72-74 C at 5000 rpm and a bit cooler at 4000.

                  I would definitely have the rectifier tested by someone who knows what they are doing. Check battery and battery connections as well.

                  Comment


                  • #10
                    Originally posted by Moonlighter View Post
                    I also think your engine temp sounds a little bit high. Mine runs at about 72-74 C at 5000 rpm and a bit cooler at 4000.

                    I would definitely have the rectifier tested by someone who knows what they are doing. Check battery and battery connections as well.
                    I agree with ML...mine runs around 68-69C. Be aware also that the higher voltage, while not knocking out your other instruments, could be causing some erroneous readings, such as a high temperature reading. You might be running cooler than the 80C that your gauge indicates, due to higher than normal voltage inputs to the temp sensor.
                    Mike
                    μολὼν λαβέ

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                    • #11
                      [QUOTE=Moonlighter;10806]I also think your engine temp sounds a little bit high. Mine runs at about 72-74 C at 5000 rpm and a bit cooler at 4000.

                      I would definitely have the rectifier tested by someone who knows what they are doing. Check battery and battery connections as well.[/QUOTE 14.7 to 15.2 is normal for a df140.

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                      • #12
                        Thanks everybody,

                        Just as an update: got the mechanic to test the boat on the water with the testing laptop plugged in. According to him he discovered voltage fluctuation - between 14.5 and 15.5 volts when the problem happens, which he considers unusual. He has contacted Suzuki and testing other motors he has in the shop to compare.

                        Will see if Suzuki considers this a problem or "normal"....

                        Comment


                        • #13
                          Rectifier/regulator

                          Hi!
                          Have a DF115 2011 model, and the same problem. have tried many times to get the Suzuki People to make a rectifier/regulato With a charging voltage at 14.4 Volt, but they says 14,9 to 15.2 is ok.
                          My opininen is the Voltag all too high.
                          The battery manufakturer says 14.4V at 20deg C When running for several hours the With high voltage batterys can start to boil asid, and is wery Dangerous.
                          Hope you understand my English.
                          Arne Henriksen
                          Norway

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