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  • Winch wiring

    On a MY20 NX does anyone know if I wire my winch negative to the battery negative or to the chassis directly. TIA.
    Bosbok

  • #2
    Hi Bosbok,

    As you are probably aware the NX Paj has a current sensor on the main earth cable to the negative terminal so ideally all current should go through the main earth lead. That being said, the earth bolt is a 6mm (10mm head) bolt and the cable from your winch is a heavier gauge than that cable so it's not ideal.

    In my Paj I have the winch earth connected to the 8 or 10mm (12 mm head) bolt AFTER the current sensor and it is all good. I measured the current that may be pypassing the sensor with the engine running and all loads on before fitment and measured it at 0.0mA so the winch does not affect the sensor when the not in operation as electricity takes the path of least resistance, which is not through the bull bar then the winch control box & motor and earth lead.

    The only thing is that when you are operating the winch that current will not be detected as a load by the current sensor but with winches usual used as an emergency thing I would rather have good current flow through the winch which MAY cause a momentary low charge rate likely to be recovered within the next few minutes of idle/drive time.

    Long story short: chuck it on the bolt after the current sensor but not the little 6mm (10 mm head) nut on the negative terminal.

    PS. I would recommend lookinh into an isolator switch for the power supply of the winch when not in use to prevent shorting and possible fire if you have a serious front end collision. I think most people don't worry about it though.

    Comment


    • #3
      Originally posted by whitso View Post
      Hi Bosbok,

      PS. I would recommend lookinh into an isolator switch for the power supply of the winch when not in use to prevent shorting and possible fire if you have a serious front end collision. I think most people don't worry about it though.
      Just a personal gut feeling apart from the obvious safety reasons for an isolator, but i would make double sure, winch cannot be operated by a passing clever fella in a car park.
      If your winch rope is passed over the roof hooked to your towbar & activated, not a pleasant thought me thinks.

      It's a very good question where should you earth it too?
      They do say negative current loads should be before the sensor, i don't like running to battery for accessories positive or negative as it become cluttered & looks dodgy.
      But 400amps good question for the earth. I would say battery at a hunch,to carry a possible 400 amps.
      Now you got me thinking as to the body is before the sensor & shorter earth cable, but its large voltage?

      Mitsubishi Pajero NX MY16 GLS with Sand Grabba floor mats, Ultragauge, Automate & Paddle gear shifters with Vlads traction control mod, Nautia switch panel, ARB compressor, Redarc Tow Pro, Anderson plug, Bushskinz front & rear alloy plates, Kaon light duty cargo barrier & rear door table

      Comment


      • #4
        Hahaha, Jasonmc73, the old winch over the roof trick! Good point. My isolator is under the bonnet as my control box is behind the grill and you need to open the bonnet to plug in the controller anyway. Side note: my hitch lives in my recovery bag not the towbar - you're welcome pedestrians.

        As I said ideally all loads should go through the sensor but the earth cable is of a smaller diameter than winch cables and will create a voltage drop plus the small bolt that is the main body earth is really not suitable for a winch. Also, if you don't actually shorten the winch cables to suit, where you mount them doesn't make a difference to voltage drop. Cable diameter and good connections (correct size lugs/bolts) absolutely will.

        Comment


        • #5
          Originally posted by whitso View Post

          As I said ideally all loads should go through the sensor but the earth cable is of a smaller diameter than winch cables and will create a voltage drop plus the small bolt that is the main body earth is really not suitable for a winch. Also, if you don't actually shorten the winch cables to suit, where you mount them doesn't make a difference to voltage drop. Cable diameter and good connections (correct size lugs/bolts) absolutely will.
          Sound advice me thinks,
          I might have to look you up one day & see where your bits are mounted before i fit a winch!
          Would like to see your box in grille, i'm wanting to do same.
          Mitsubishi Pajero NX MY16 GLS with Sand Grabba floor mats, Ultragauge, Automate & Paddle gear shifters with Vlads traction control mod, Nautia switch panel, ARB compressor, Redarc Tow Pro, Anderson plug, Bushskinz front & rear alloy plates, Kaon light duty cargo barrier & rear door table

          Comment


          • #6
            Originally posted by whitso View Post
            As I said ideally all loads should go through the sensor but the earth cable is of a smaller diameter than winch cables and will create a voltage drop plus the small bolt that is the main body earth is really not suitable for a winch.
            The bolt shouldn't be carrying the earth current. If Mitsubishi put things together properly, there shouldn't be paint under the lug, so current flow should be straight from body to lug to cable.

            In my opinion, the short length of the earth cable will have negligible voltage drop - maybe 0.2 mV/A, or 20mV per 100A. If the winch draws 500A, that would be about a 0.1V drop, or around 1% of nominal system voltage.

            In terms of current rating, this is primarily about protecting the insulation from overheating and preventing shorts. For the battery earth cable, the insulation is cosmetic - a bare copper cable would work just as well. Outside competition use, a winch wouldn't be in use for long enough for the factory earth cable to be adversely affected.

            Long story short, I wouldn't worry about that earth cable as a "weak point" in an "body return" for a winch. I would be worried about what other bolted joints might be in the return path, and how electrically sound they might be - that's up to the installer to consider.

            In terms of the ultimate system performance / reliability, the best solution would be big cables of shortest practical length with the absolute minimum number of connections - so earth the winch straight to the battery. My winch is earthed via the body (by the previous owner) and it's worked the few times I've needed it.

            NT Platinum. DiD Auto with 265/70R17 ST Maxx, Lift, Lockers, Lockup Mate, Low range reduction, LRA Aux tank, bull bar, winch, lots of touring stuff. Flappy paddles. MMCS is gone!

            Project: NJ SWB. 285/75R16 ST Maxx, 2" OME suspension, 2" body lift, ARB 110, 120l tank, bullbar, scratches, no major dents. Fully engineered in SA. NW DiD & auto in place - a long way to go....

            Scorpro Explorer Box

            Comment


            • #7
              Originally posted by nj swb View Post

              The bolt shouldn't be carrying the earth current. If Mitsubishi put things together properly, there shouldn't be paint under the lug, so current flow should be straight from body to lug to cable.

              In my opinion, the short length of the earth cable will have negligible voltage drop - maybe 0.2 mV/A, or 20mV per 100A. If the winch draws 500A, that would be about a 0.1V drop, or around 1% of nominal system voltage.

              Long story short, I wouldn't worry about that earth cable as a "weak point" in an "body return" for a winch. I would be worried about what other bolted joints might be in the return path, and how electrically sound they might be - that's up to the installer to consider.

              In terms of the ultimate system performance / reliability, the best solution would be big cables of shortest practical length with the absolute minimum number of connections - so earth the winch straight to the battery. My winch is earthed via the body (by the previous owner) and it's worked the few times I've needed it.
              I think that's fair as well.
              Both will work, but to the battery would have less electrical joins which makes sense might be best option

              Mitsubishi Pajero NX MY16 GLS with Sand Grabba floor mats, Ultragauge, Automate & Paddle gear shifters with Vlads traction control mod, Nautia switch panel, ARB compressor, Redarc Tow Pro, Anderson plug, Bushskinz front & rear alloy plates, Kaon light duty cargo barrier & rear door table

              Comment


              • #8
                Thanks all, the battery terminals are very congested with Redarc BCDC, aux, Towpro etc. Would it matter if I connected the winch to the second battery?

                Comment


                • #9
                  Hi Bosbok,


                  Connecting to the secondary battery would not be suitable. You mentioned the redarc bcdc, is that a dc-dc inverter? If so it will usually only have around 6mm wiring from the secobdary battery to the start battery as the inverters only put out 25A or something like that. If you had heavy B&S cable joining battery negative terminals it would be OK but not the best option.

                  By the way, those loads you mentioned should all be earthing before the current sensor. Really the only cables after the sensor should be your earth lead to the secondary battery and the winch cable if you chose to go that way. I'd recommend seeing an auto-elec to tidy that stuff up or you could probably replace all the terminals with 6.3mm ring terminals and bolt them to the earth point closest to the battery if you are keen to diy.

                  Hope that all helps!

                  Comment


                  • #10
                    Originally posted by Bosbok View Post
                    Thanks all, the battery terminals are very congested with Redarc BCDC, aux, Towpro etc. Would it matter if I connected the winch to the second battery?
                    What i have done out of interest, is fitted an 80 amp circuit breaker for Positive, all my positive wires run to this, to the hot & cold side depending on the wire.
                    Hot side/ battery side is merely to pick up the positive power in lieu of running to battery.
                    One 4 B&S runs from my battery to the circuit breaker.
                    My earths are Chassis

                    I don't have 2nd battery but do have feed to trailer 4 B&S length of car for BCDC40, 40 amp in camper though.

                    Also Tow Pro

                    Just an option to keep some accessories off the battery terminals.

                    Mitsubishi Pajero NX MY16 GLS with Sand Grabba floor mats, Ultragauge, Automate & Paddle gear shifters with Vlads traction control mod, Nautia switch panel, ARB compressor, Redarc Tow Pro, Anderson plug, Bushskinz front & rear alloy plates, Kaon light duty cargo barrier & rear door table

                    Comment


                    • #11
                      Originally posted by nj swb View Post

                      The bolt shouldn't be carrying the earth current. If Mitsubishi put things together properly, there shouldn't be paint under the lug, so current flow should be straight from body to lug to cable.

                      In my opinion, the short length of the earth cable will have negligible voltage drop - maybe 0.2 mV/A, or 20mV per 100A. If the winch draws 500A, that would be about a 0.1V drop, or around 1% of nominal system voltage.
                      Out of interest u checked nj swb numbers. An extra 30cm of 0awg cable at 300 a load will drop 60mv. I thought it would be higher myself, hence why I checked.

                      In the interests of being scientifically correct and being "that guy", the current would flow from battery negative down cable to lug to body, electricity being of negative charge, and return path is technically the positive side. It's neither here nor there, I just want to try and big note my limited knowledge and try and belittle people on an internet forum from the anonymity of a screen in order to make myself feel better because my limited interpersonal skills has led to me having feelings of inferiority and low self worth

                      Comment


                      • #12
                        Originally posted by disco stu View Post

                        Out of interest u checked nj swb numbers. An extra 30cm of 0awg cable at 300 a load will drop 60mv. I thought it would be higher myself, hence why I checked.

                        In the interests of being scientifically correct and being "that guy", the current would flow from battery negative down cable to lug to body, electricity being of negative charge, and return path is technically the positive side. It's neither here nor there, I just want to try and big note my limited knowledge and try and belittle people on an internet forum from the anonymity of a screen in order to make myself feel better because my limited interpersonal skills has led to me having feelings of inferiority and low self worth

                        I recall in high school someone waffling on about electrons along those lines
                        But mine are special & flow red to black
                        Mitsubishi Pajero NX MY16 GLS with Sand Grabba floor mats, Ultragauge, Automate & Paddle gear shifters with Vlads traction control mod, Nautia switch panel, ARB compressor, Redarc Tow Pro, Anderson plug, Bushskinz front & rear alloy plates, Kaon light duty cargo barrier & rear door table

                        Comment


                        • #13
                          Ahh beat me to it!

                          Comment


                          • #14
                            Originally posted by Jasonmc73 View Post

                            Sound advice me thinks,
                            I might have to look you up one day & see where your bits are mounted before i fit a winch!
                            Would like to see your box in grille, i'm wanting to do same.
                            I love the control box behind the grille but to be honest it was a pain in the arse. If I has to do it again I'd buy the TJM winch and mount the controller recommended in the instructions. I'll get some photos though next time I have the grille off to clean the bugs out of the radiator.

                            Comment


                            • #15
                              Originally posted by Jasonmc73 View Post


                              I recall in high school someone waffling on about electrons along those lines
                              But mine are special & flow red to black

                              Your poor long suffering science teacher!

                              Comment

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