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Solar & Battery Power Advice Please

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  • Solar & Battery Power Advice Please

    I have a big trip planned this weekend and I wrecked my TT this morning going in to a parking structure. Thanks in advance for your sympathy, but what I really need is your ideas on portable power as I'll be transitioning to tent camping with no power hookup.

    I use a CPAP machine, and have an 80 amp hour lead acid battery, and a 100W solar panel and charge controller. The CPAP label says it uses 6.7A at 12V. By my calcs 6.7a x 8hr I need 54 amp hours which is just about the right draw-down for an 80ah battery. We'll be camped in a somewhat shady area but I think my solar panel can top of my battery during the day.

    Do you suppose it's more efficient to

    - use the CPAP's 12V DC power cord, attached to the battery with a cigarette lighter adapter
    or
    - use the CPAP's 110V power supply for the CPAP plugged in to the 300W inverter, attached to the battery

    I'm leaning towards running on the DC power cord. Surely there will be losses going from the 12V battery to the 110v inverter, then through the CPAP's 110v power supply back to 12V.

    amIright?

  • #2
    Or, would I be better of with some sort of portable power pack? The problem is I need to recharge it with my solar panel with SAE connectors on the charge controller. It would need to be available locally - there are a few harbor freights and camping world stores around here.

    Comment


    • #3
      Sympathy acknowledged...

      I would go with the 12V connection to the battery. There is some inefficiency when inverting power, so no need to use a go-between. Just keep your solar panel in the sun as much as you can, even if it means moving it frequently.

      Jim
      Jim and Ginnie
      2024 Solitude 310GK
      GDRV Technical Forum Moderator
      GDRV Rally Support Coordinator

      Comment


      • #4
        The problem with frequent moves of the solar panel are that we'll be ass-deep in the cool waters of the Arkansas river in southern Colorado. The good news is my guys like to cook large breakfasts so we don't leave camp 'till around 9 so I'll have a good 3-4 hours of sunlight where I can keep it adjusted in the morning before we leave.

        Comment


        • #5
          A typical 100 watt panel will harvest an average of 30 amp hours of power per full day of sunshine.
          Jim and Ginnie
          2024 Solitude 310GK
          GDRV Technical Forum Moderator
          GDRV Rally Support Coordinator

          Comment

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