Announcement

Collapse
No announcement yet.

Off Grid Solar help 2 6volt batteries, 100W solar panel, 20AMP charge controller

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Off Grid Solar help 2 6volt batteries, 100W solar panel, 20AMP charge controller

    Hi
    I have a solar panel set up on my van. I have a 100 Watt Solar Panel, a 20 AMP control charger & 2 x 6 volt deep cycle batteries T105 trojan. I have a 12 Volt Coleman thermoelectric wired into the batteries through the 12 volt DC and a fantastic vent wired to the solar power control charger!
    The Fridge runs on 4AMPS p/hr and is 12 V so thats 48 W an hour. = 1152 watts for 24hrs
    When the batteries on the solar control say 13 Volts and i connect the fridge to the batteries it doesn't even last 24 hours without draining the batteries.
    I have done calculations to the best of my knowledge but i think the fridge drains too much power.
    Please help advise me on what i can do to improve my system. I am currently living off grid in Mexico and don't have enough power to turn on my inverter as i don't want to kill my batteries. My food also keeps spoiling.
    The batteries i bought were second hand and tested before use. I think this may be the problem. But please provide any advice you have to help me! Wound appreciate it so much. Cheers, Sami

  • #2
    You need more solar panels. You are probably generating only 600 Wh at best, not enough to cover the 1152 Wh of consumption. You need to get the batteries charged to around 14.8 V, if you can only charge to 13 V you won't have full capacity.

    If your charge controller is PWM type, you'd be better off starting over with a pair of 250 - 300 W panels and a model 3210A Tracer 30 A charge controller.
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

    Comment


    • #3
      Thanks Sensij! So my only option is adding more solar panels? Is there a way around this?

      Comment


      • #4
        I have more than a thousand watts of panels to successfully run a small chest fridge. A 100W panel would barely power the fridge at the best part of the day. Even your unrealistic overly optimistic calculations don't get you near that.

        Comment


        • #5
          Originally posted by sami_h23 View Post
          I have a solar panel set up on my van. I have a 100 Watt Solar Panel, a 20 AMP control charger & 2 x 6 volt deep cycle batteries T105 trojan. I have a 12 Volt Coleman thermoelectric wired into the batteries through the 12 volt DC and a fantastic vent wired to the solar power control charger!
          The Fridge runs on 4AMPS p/hr and is 12 V so thats 48 W an hour. = 1152 watts for 24hrs
          When the batteries on the solar control say 13 Volts and i connect the fridge to the batteries it doesn't even last 24 hours without draining the batteries.
          I have done calculations to the best of my knowledge but i think the fridge drains too much power.i
          So what is the problem? It is doing exactly what you designed it to do. FAIL

          Your Fridge uses 1200 wat hours per day.
          You have a 100 watt panel with 20 amps PWM controller that can only generate 200 to 300 watt hours per day.
          You have a set of golf cart batteries that can only deliver 800 watt hours per day.

          It is working perfectly fine. Your battery should be destroyed in a week or two from abuse and neglect. You got what you asked and designed for.

          If you want this to work you need:

          Panel Wattage = 400 watts
          40 Amp MPPT Charge Controller
          4 6-Volt Golf Cart Batteries.

          Problem solved.

          MSEE, PE

          Comment


          • #6
            Originally posted by sami_h23 View Post
            Thanks Sensij! So my only option is adding more solar panels? Is there a way around this?
            Yes. Get rid of the solar panels and buy a Battery Isolator and more batteries. Let your engine alternator charge the house batteries. Otherwise you need 400 watts of panels, 40 amp MPPT controller, and more batteries.
            MSEE, PE

            Comment


            • #7
              Thanks for the advice! I have a battery isolator i was planning on installing so i will do that!
              I was curious if i can still have it connected to the solar?

              We also have decided we are going to turn the fridge into an ice chest so we can use the inverter to power the fan, laptops and phones.

              We don't have access to buying a new ARB fridge and we can't add more panels to our van as we don't have the room on the roof or space for more batteries in the van.

              Comment


              • #8
                yes. for your "house" (not starting battery) you CAN add solar, but the expense, space they take up, holes in your roof, are they worth it, or a small inverter genset & 40A battery charger
                ( 15V @ 40 A = 600W x power factor .6 = about 1Kw genset needed) A little genset running 1 or 2 hours a day, better than starting your car for 2 hours of idling to charge battery)
                Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                solar: http://tinyurl.com/LMR-Solar
                gen: http://tinyurl.com/LMR-Lister

                Comment


                • #9
                  Originally posted by sami_h23 View Post
                  I was curious if i can still have it connected to the solar?
                  Yes Sir, standard practice. The panels will just extend you battery run time. When you start the engine, the panels basically get turned off because the alternator is a higher source, and will fool the controller into thinking the battery is fully charged. It is passive and not something you have to do.
                  Last edited by Sunking; 07-09-2017, 01:28 AM.
                  MSEE, PE

                  Comment

                  Working...
                  X