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Dual battery system

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    John Crafford
    Participant

    I tow a Sprite Tourer SP with a 2009 Defender Puma 2.4. My tow combination for the past 4 years. The Tourer comes standard with aNational Luna week ender 50lt fridge/freezer and the caravan battery is charged via a BH plug from the Defender’s battery through the normal caravan electrical set-up.

    I also have a National Luna Power pack and a Dometic CF 50 fridge/freezer for the Defender.

    Question. Can I run both the Caravan charge system and the National Luna power pack from the Defender battery or should I have a stronger alternator installed. I do not run them simultaneously at present. We are not “December” campers but  do sight seeing and exploring trips when on holiday.

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    Chris Manley
    Chris Manley on

    I wouldn’t recommend running two fridges off of one battery.  You are going to drain the battery faster than you can charge it.  The last thing you want is arriving at your camp site with a flat or almost flat battery, you’re never going to recover, even with a solar panel.

    Chris.

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    John Crafford
    John Crafford on

    Thanks Chris, it will certainly make me think again.

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    Mike Penny
    Mike Penny on

    Hi John,

    Yes you can. Provided you run the fridges while driving and not when stationary for long periods (a few hours or more), you will have no problems. I charge and run the large battery in my caravan which runs my 100L bar fridge in the caravan via a invertor plus I run my Dometic 50L fridge in the car with no issues whatsoever. This I have done with three different tow vehicles. A fridge draws about 5 times its running power on start-up but then settles down and only uses about 100 Watts to run (a little less than a set of spots or your cars headlights). Your cars alternator has a massive amount of spare capacity  and should put out in the region of 80 to 160 (or more) Amps depending on model whereas your two fridges would draw about 20 amps max when running  – and they don’t run all the time, they cycle on and off.

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    EXPO CAMPER
    EXPO CAMPER on

    John, there is no need for an alternator upgrade, however even with large loads it is important to have control over how much power is taken from the standard alternator.

    The loads you have (fridges) are not really a big deal when travelling, it is more the state of the battery that will draw a higher current and that added to the load is what you need to know having the setup you do..

    Short answer, you can run 7 additional batteries in a system as long as there is proper control over the current loading the standard alternator, thus working safely..

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    John Crafford
    John Crafford on

    To Mike Penny and Expo Camper, a big thank you for your input. Yes, the system will only be used while driving and as the crank battery runs through the NL power pack to the other batteries I can switch off when stopping. Thanks again for the peace of mind.

     

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