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  • bbekk2
    Junior Member
    • Jan 2013
    • 5
    • Brisbane

    DC to DC Charger vs Battery Isolator

    I have a 2013 NW Pajero and I am in the process of wiring up an auxillary battery for my Waeco 40L fridge in the rear of the wagon.
    I read somewhere that most 4WD's built after 2010 have cut back on the output from their alternators and that a DC to DC charger was needed to bring the second battery up to full charge. Is this the case?
    I was about to hand over some coin for a Projecta 25A DC to DC charger but if the alternator pumps out enough for both batteries to fully charge, then I can purchase a Projector 150 dual battery isolator for less than half the cost of the DC to DC charger. Will the isolator do the job?
    Thoughts?
  • nj swb
    Resident
    • Jun 2007
    • 7327
    • Adelaide

    #2
    As the owner of a Redarc 20A DC-DC system, I suggest starting with the isolator and see if it meets your needs.

    While you're outlaying money to install the dual battery system, save a little with the isolator and put the cash towards ensuring decent sized wiring and quality connections. If, somewhere down the line, you're not happy with the Isolator, flog it off to somebody here (it will sell) and then buy a DC-DC device.
    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

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    • jimsutt
      Member
      • Jun 2012
      • 72
      • Sydney

      #3
      Your alternator is most probably a smart one in which case you must use a dc to dc charger otherwise your aux battery will not charge properly.. There are other posts on here explaining all you need to know..

      Sent from my SM-G900T using Tapatalk

      Comment

      • Dicko1
        Valued Member
        • Dec 2014
        • 7621
        • Cairns, FNQ

        #4
        I,ve always used the redarc sbi12 in previous vehicles. Worked a treat (better than the old aluminium pot solenoid). However with the purchase of the NW and the variable alternator fitted I bought the Redac bdc1220-ign . Two and a half years later and aux batteries are always fully charged and now it also supplies power to the batteries in my camper.Both my auxillary batteries are in the rear tub. Having done shiploads of work on 12 volt solar systems and vehicle systems I went down the dcdc route. Particularly if you intend to get a camper or caravan or even move your aux battery to the tub. It is possible that the vsr could do the job. I just wanted to do it right the first time.
        Dicko. FNQ

        2014 NW with all the usual stuff plus more.

        TIME....1000 times more valuable than money

        Comment

        • psproule
          Valued Member
          • Jun 2007
          • 3680
          • Googong, NSW

          #5
          Personally I highly recommend a quality DC DC charger over a relay. That's after boiling many an AUX battery in the old NP with a Redarc relay setup. A decent DC DC charger will do a number of things that a relay cant; It will ensure that the charge rate into the battery is correct for it's current state of charge and will compensate for the battery chemistry, it will output a higher voltage than the alternator / crank battery ensuring a 100% charge of the AUX and it will prevent over-charging & damage to the battery by entering float charge at the appropriate point. I fitted the Projecta DC DC charger to our new NX as it can select the different battery chemistry and has a proper ignition sense line for switch-on / off. Have fitted some of the Redarc's to friends cars and it is good too, but bulkier and you need the right variant depending on application.

          A relay will work OK, but in my experience will be harder on the battery.

          Pat
          2016 Mitsubishi NX Pajero GLX
          2011 Landrover Freelander II SD4

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          • sharkcaver
            "2000"+ Valued Contributor
            • May 2009
            • 6270
            • Perth

            #6
            Not to mention, if you run the IDC25, you then have access to a quality MPPT solar regulator as well. For the $150 extra in price of an IDC25 over a standard VSR, you could probably loose most of that with the size of the wire required if your battery is rear mounted. I have a bcdc1240 in the camper and the IDC25 in the car. Feature wise, the Projecta craps all over the redarc IMO....Pity they don't do a 40 amper for the camper.
            MY16 NX GLX5 with just a few bits added. MY14 D-max spacecab, also with a few bits added.

            My Journeys

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            • Tamworth
              Member
              • May 2014
              • 100
              • Tamworth

              #7
              Solenoid V DC-DC

              I own a June 2014 NW with a simple solenoid system originally installed on my NP in 2003 to run our 50L Waeco and then put into our NS, now in our NW
              It was installed by my auto electrician and I've done 120 000km since in the NW, having replaced one small deep cycle second battery after 18 months The fridge sits in the vehicle for probably only 2-3 weeks pa
              No doubt the DC to DC will maintain a superior charge and look after the battery better than the solenoid, but the solenoid (same as isolator?) has done the job for me.
              Perhaps the "smart" alternator in the NW isn't as smart as some other vehicles ?
              Mark

              Comment

              • Outbound Brown
                Junior Member
                • Dec 2010
                • 38
                • Gold Coast

                #8
                I just went through this for our NX. As we won't be using the 3rd row of seats I went with AGM and DCDC charger in the seat tub. As battery is only used when we are away the rest the time the charger is able to maintain it. If you were running a fridge all the time maybe that's not an issue ?? Given the cost a decent AGM I thought it was best to maintain it. As Sharkcaver mentioned you also have solar regulator and with the redarc they compatible with lithium which may future proof your setup.


                Sent from my iPad using Tapatalk
                04 NP Exceed - Lovell 2" lift, LR tank, ARB Bull bar, Rhino roof track, Hankook AT, Airtec snorkel, 2nd battery, Bushskinz sump guard, rusty IPF spotties

                16 NX GLS - Bilstein / Lovell 2" lift, Airbags, Bushskinz side steps and intercooler / sump guards, TJM Bull bar, Airtec Snorkel, GME TX3550, Illuminator 9" LED spotties, 17" NS alloys BFG 265/70/17 AT, Rhino Pioneer platform, Frontier LR fuel tank

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                • jimsutt
                  Member
                  • Jun 2012
                  • 72
                  • Sydney

                  #9
                  A quick ring to Redarc and the technical guy will tell you of your car has a smart alternator. You will fingers all modern cars have them .. It's knowing when they were first installed ..

                  Sent from my SM-G900T using Tapatalk

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                  • sharkcaver
                    "2000"+ Valued Contributor
                    • May 2009
                    • 6270
                    • Perth

                    #10
                    Originally posted by Outbound Brown View Post
                    As Sharkcaver mentioned you also have solar regulator and with the redarc they compatible with lithium which may future proof your setup.
                    I know very little about Lithium. But I hear the Li profile of the redarc has been set for one specific brand of Li. Most other manufacturers specify a lower float voltage than what the redarc puts out. So if you buy a redarc for potential Li setup in the future, do some research first.
                    MY16 NX GLX5 with just a few bits added. MY14 D-max spacecab, also with a few bits added.

                    My Journeys

                    Comment

                    • bbekk2
                      Junior Member
                      • Jan 2013
                      • 5
                      • Brisbane

                      #11
                      Thanks for the advice everyone. I have ordered a Projecta DC to DC charger and will wire it up myself. Just two questions: should I put a circuit breaker fuse on the auxiliary battery (located in the rear of the Paj)??

                      Secondly, where should I mount the DC to DC charger in the engine bay? Does anyone have any photos showing their fitment?
                      Thanks in advance.

                      Sent from my SM-G920I using Tapatalk

                      Comment

                      • nj swb
                        Resident
                        • Jun 2007
                        • 7327
                        • Adelaide

                        #12
                        One of the benefits of a DC-DC charger is that it can compensate for the voltage drop on long cable runs - which you're foregoing if you mount the charger under the bonnet and the battery in the rear.

                        Mount the charger as close to the aux battery as you can.
                        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

                        • bbekk2
                          Junior Member
                          • Jan 2013
                          • 5
                          • Brisbane

                          #13
                          That's good advice. Cheers.
                          Do I need to have a circuit breaker?

                          Sent from my SM-G920I using Tapatalk

                          Comment

                          • sharkcaver
                            "2000"+ Valued Contributor
                            • May 2009
                            • 6270
                            • Perth

                            #14
                            Originally posted by bbekk2 View Post
                            That's good advice. Cheers.
                            Do I need to have a circuit breaker?

                            Sent from my SM-G920I using Tapatalk
                            Yes. Both at the main battery (which feeds the IDC25) and at the outlet for the Aux, or you have unprotected wiring.

                            I mounted my IDC to the wall of the rear seat well, just under the lid. I also removed the plastic tub.
                            MY16 NX GLX5 with just a few bits added. MY14 D-max spacecab, also with a few bits added.

                            My Journeys

                            Comment

                            • wazza1965
                              Member
                              • Mar 2011
                              • 176
                              • Brisbane

                              #15
                              Originally posted by sharkcaver View Post
                              Not to mention, if you run the IDC25, you then have access to a quality MPPT solar regulator as well. For the $150 extra in price of an IDC25 over a standard VSR, you could probably loose most of that with the size of the wire required if your battery is rear mounted. I have a bcdc1240 in the camper and the IDC25 in the car. Feature wise, the Projecta craps all over the redarc IMO....Pity they don't do a 40 amper for the camper.
                              Second on the IDC25 with sharkcaver. I run one in the back of my Pajero and it works brilliantly. Charges my AGM at 14.4v quickly then floats at 13.7v. It also provides a three stage charging rate with a built in MPPT controller from my roof mounted 2x 120w solar panels when stationary. It will prioritise solar charging then change to alternator if it feels the extra current is needed.
                              No additional relays required all in one compact very easy to install package.
                              NM2002 Exceed DID. Safari Snorkel, Garrett GTX2863R Turbo, HPD Intercooler, Synergy / Turbosmart controllers, Mandrel 3" Exhaust Pyro, Built auto, ECB Bar with 12,000lb Winch & Dyneema rope, Rotronic battery system, 2x 120Amp/h AGM AUX batteries, Lovell 2", Airbags, Rhino AT2012, Fiamma Awning. 4x IPF spots 120w HID inserts. Alpine NAV Bluetooth with Type R sound system, UHF Uniden UH8080NB, Couplertec. Rear draw system, 1500w inverter. ARB twin comp / tank, ARB Locker. Evakool. NASA BM-1.

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