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Dual Battery Problems

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  • Dual Battery Problems

    G’day all, I have a dual battery setup in my fortuner running a redarc BCDC1225D and the charger is running the main battery down to 12v before cutting out which is what it is designed to do however the car won’t start with the battery at 12v. the main battery is an N70ZZMF and is 3 years old. We have been overcoming this in the short term by jumping across from second battery with jumper leads but this is far from ideal. Any ideas on how to overcome this problem?

  • #2
    I dont have any experience with the Redarc units but i presume they should disconnect when the ignition is switched off. thats the way i wired up my Ironman DCDC. Is there an Ignition input on the Redarc ? download a wiring diagram and see if its installed correctly.
    2019 GX , in White


    • #3
      I've no knowledge of motors or electrics, but have you tried an auto electrician to to have the battery load tested to see if the main battery has died? As White One said, check the wiring if you can, and even ring Redarc if you need to pick their brains.

      The battery at 3 yrs old may be on its way out. Having it load tested could help. Good luck.


      • #4
        After some testing with a multi meter during the charging process and paying attention to the charger. It will continue to charge the second battery until the first battery gets down to around 12v I wasn’t sure if the battery had something else drawing it down once the charger cut out but can confirm it doesn’t as once the charger cuts out the battery recovers to 12.2-12.4v but still won’t start the car. it should be shutting off at 12.7 but it doesn’t it doesn’t need a trigger wire in order to do this I can attach the trigger wire to ignition so that it only charges when the car is running but I think there must be internal issues with the charger. Taking it to get seen to Monday.


        • #5
          Ok I think I have the problem solved, for the BCDC1225D the three trigger wires need to be all disconnected from everything to charge regular Lead Acid Batteries and cut out at 12.7V the three trigger wires were not attached to any wires on the car but they were all taped up together with the wires touching each other and partially exposed to touch on the engine bay/firewall of the car behind the battery. I trimmed the excess wire folded and taped each wire over on themselves and then taped them all together nice and tight the charger now cuts out at 12.7V and car starts good again! I might still consider setting the relevant trigger wire to only charge with a running car so as to ensure as much starting voltage as possible.