DC2DC charging





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Thread: DC2DC charging

  1. #1
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    Default DC2DC charging

    This fred is becoming long, complicated with too much sub - topics.

    It seems as if DC2DC chargers is the way to go to maintain your batteries when you are touring and don't have time to do decent charging with a C-tek or something simular.

    Let use this fred to discuss installation and operation procedures and the pro's and con's of DC2DC charging.

    I assume that you still have to fit a isolating solenoid to protect the cranking battery from running flat when the engine is not running. Like 4EP said, the DC2DC charger runs from the Main battery?
    Last edited by Dirk; 2010/01/26 at 09:38 AM. Reason: Title
    Everything is a hammer.
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  2. #2
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    Hi 4ePajero

    Ah, I see the misunderstanding. Completely agree with you, but the DC-DC charger as described by OllieNoster switches load to the alternator and in doing so isolates the aux battery from the alternator circuit. So appliances are powered by the alternator and the aux battery and battery charger are on a separate circuit.

    Uys. The charger should not be running when the engine is off, so there shouldn't be a need to fit an isolating solenoid. Even the less well equipped DC-DC chargers have an on-off signal input, whatever signal you were planning to drive the solenoid can be used to switch the charger on directly. The only time this will be needed is if the charger doesn't switch load when the engine is running.

    Edit: But even if it doesn't switch load, your main battery should still be fine, the aux is just charging slight less efficiently.

    Quote Originally Posted by 4ePajero View Post
    Simply because the alternator is definitely not the best way to charge a deep cycle battery!

    (I thought we had consensus on that!)

    Running other devices from the alternator is fine.
    Last edited by tsblack; 2010/01/22 at 10:32 AM. Reason: Addition.

  3. #3
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    Hiya

    I think you could still have some problems. If you have one full battery and one flat battery, charging of the flat battery is always going to be masked by the full battery because the alternator's voltage sense line detects the voltage on the full battery and not the flat battery and adjusts it's output accordingly. So it will still take a really long time to charge up an aux battery, be it normal lead acid or deep cycle.

    Although if you're using a normal lead acid you shouldn't be running it as flat as deep cycle, so the period to charge may not be a noticeable issue for you.

    Quote Originally Posted by RedLineR View Post
    Am I right in saying that all these fancy bits are only if you use deep cycle batteries as opposed to normal lead acids as the secondary battery?

  4. #4
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    Quote Originally Posted by tsblack View Post
    Edit: But even if it doesn't switch load, your main battery should still be fine, the aux is just charging slight less efficiently.
    And then you also wouldn't need thinker cables, cause your fridge will always run directly off your aux battery, and never from the main battery/alternator circuit.
    Wouter van Rooyen
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    OK soos ek alreeds gevra het waar kry 'n mens nou 'n 12v DC2DC laaier. Al die planne en ons kry nie 'n goeie laaier nie sal niks help nie.
    Ben

    RY WAAR JY MAG MET PASSIE

    2009 Toyota Hilux 3.0 D4D DC 4X4

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    Ben, ek sien jy vra en vra en vra, en niemand antwoord nie. PM vir JohanP en vra hom, hy weet van iemand wat goeie vir 'n goeie pryse verkoop. As jy dit kry, post sommer hier sodat ons almal weet.

    Ek sien 'n group buy in die nabye toekoms......
    Everything is a hammer.
    Unless it is a screw driver.

    Then it it a chisel.

  7. #7
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    I have just received a DC/DC charger from Manie at HCdp electronics in Pretoria these guys seem to know what they are talking about. on my previous vehicle I used the NL system with BH plug to charge the trailer aux battery. Now I have bought a new discovery and with all the electronics I am not keen on cutting into the system to charge with a NL system so I want to plug the DC/DC charger into the aux plug next to the std trailer plug on the discovery to charge the aux battery. Manie at HCdp agrees that this will work well for keeping the Aux battery topped up while touring.
    Discovery 4 HSE
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  8. #8
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    JTF Manufactuing in Cape Town sells a DC-DC charger for R1380.00. This is a BC 1212-13.75
    HCDP Electronics in PTA sells a 12DC14DC10A @ R895 VAT included less or 12DC14DC05A @ R690 VAT included

    But still I'm also not sure how to exactly install it.
    And if one can use a Benton BX-1 with a DC-AC inverter to run it?


  9. #9
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    Quote Originally Posted by Whisky View Post
    OK soos ek alreeds gevra het waar kry 'n mens nou 'n 12v DC2DC laaier. Al die planne en ons kry nie 'n goeie laaier nie sal niks help nie.
    See attachment for details on the charger I am referring to.

    R1380 inc Vat, plus R200 extra for the auto voltage detection (if needed)
    Ex. delivery.

    Contact Jean Theart at jeanthrt ("at") gmail ("dot") com
    Attached Files Attached Files
    Wouter van Rooyen
    Discovery 3 Tdv6
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  10. #10
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    Aaa nou kom ons iewers!!!!!

    Dankie,
    Ben

    RY WAAR JY MAG MET PASSIE

    2009 Toyota Hilux 3.0 D4D DC 4X4

  11. #11
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    Quote Originally Posted by OllieNoster View Post
    See attachment for details on the charger I am referring to.

    R1380 inc Vat, plus R200 extra for the auto voltage detection (if needed)
    Ex. delivery.

    Contact Jean Theart at jeanthrt ("at") gmail ("dot") com
    From the file in this post:
    1) THE UNIT IS ALSO EQUIPED WITH A LOAD SHEDDING FUNCTION WHEREBY ANY LOAD (FRIDGE) OF THE AUX BATTERY IS AUTOMATICALLY CONNECTED TO THE CARS’ MAIN BATTERY ON STARTING UP THE ENGINE, LEAVING THE AUX. BATTERY VOID OF ANY LOAD. THIS ENABLES THE AUX BATTERY TO BE FULLY CHARGED MUCH SOONER THAN WOULD OTHERWISE BE THE CASE.
    Clever.

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    Quote Originally Posted by 4ePajero View Post
    Clever.
    Yeap,

    but, presuming all this is installed in a trailer, is the reason why you would still need the thicker cables from the main battery to the DC charger.

    The charger won't mind the voltage drop of thinner cables, but the
    fridge, now running on power directly from the vehicle, might.

    It'll also be competing with the DC charger for power.
    Wouter van Rooyen
    Discovery 3 Tdv6
    Defender 90 Tdi

  13. #13
    4ePajero Guest

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    Quote Originally Posted by OllieNoster View Post
    Yeap,

    but, presuming all this is installed in a trailer, is the reason why you would still need the thicker cables from the main battery to the DC charger.

    The charger won't mind the voltage drop of thinner cables, but the
    fridge, now running on power directly from the vehicle, might.

    It'll also be competing with the DC charger for power.
    Why?

    Voltage drop (or the prevention thereof) is the only motivation for thick cables.

    A fridge will happily run on the voltage available (after the voltage drop in 'thin' cables).
    Let's say 14.1V (alternator) less 2V (drop due to 'thin' cables) = 12.1V, which is fine for your fridge.

    Test it. Fit 2.5mm sq cables (of the length you will need) from your cranking battery to your fridge (6m?).
    Start the engine.
    Check the voltage and see whether your fridge will run.

  14. #14
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    I see we are starting to get some conflict in the end goal. I want to get away from laying cables to the back and then being able to charge the aux battery properly. If someone can help me if while I am driving using a DC/DC charger and I have a 40l Engel running will the charger be able to fill the battery and keep the fridge running
    Discovery 4 HSE
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  15. #15
    4ePajero Guest

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    Quote Originally Posted by DiD32 View Post
    I see we are starting to get some conflict in the end goal. I want to get away from laying cables to the back and then being able to charge the aux battery properly. If someone can help me if while I am driving using a DC/DC charger and I have a 40l Engel running will the charger be able to fill the battery and keep the fridge running
    The Engel draws 5A (me finks).

    Now look at the document attached to Ollienoster's post.
    Depending on the discharge of the aux.battery, the DC-DC charger will charge at up to 13.75A.

    Short answer: Yes

  16. #16
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    Now a stupid question. What will happen if you take one of these two chargers and plug it into the cigarette lighter fitting and attach it to the battery? Instead of laying extra cables?

  17. #17
    4ePikanini Guest

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    Quote Originally Posted by jaco_n View Post
    Now a stupid question. What will happen if you take one of these two chargers and plug it into the cigarette lighter fitting and attach it to the battery? Instead of laying extra cables?
    The fuse will blow if the battery is very flat

    EDIT : Had a scary thought.....with all that current running through old thin brittle wires.... what if the fuse doesn't blow?



    Don't take shortcuts with electrics!
    Last edited by 4ePikanini; 2010/01/22 at 02:08 PM.

  18. #18
    4ePajero Guest

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    Quote Originally Posted by jaco_n View Post
    Now a stupid question. What will happen if you take one of these two chargers and plug it into the cigarette lighter fitting and attach it to the battery? Instead of laying extra cables?
    That will depend on

    • the rating of your cigarette lighter fitting.
      It will have to be more than the max. charge rate of the DC-DC charger you use
    • the max. charge rate of the DC-DC charger.

    I would say it need to be rated at 50% more than the charger.
    Thus, if you choose a 15A charger, your ciggy lighter had better be good for 22.5A.
    I don't think the average cig plug will make it.

    A Hella plug would be a better option.

  19. #19
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    bigger fuse? :-)

  20. #20
    4ePikanini Guest

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    Quote Originally Posted by jaco_n View Post
    bigger fuse? :-)
    see my edit above

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