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Thread: generic dual battery and solar Q's after searching

  1. #1

    Default generic dual battery and solar Q's after searching

    Hello everyone, I have been frequenting ih8mud forever and lately my needs are leaning towards those most common for expedition use. Reading various setups about dual batteries, solar panels, and electrical setups has been overwhelming as I am electrically challenged. My needs have increased since I bought an ARB fridge. My goal is to be able to run it continuously while camping for extended periods without starting or moving the truck. Powerfilm solar panels are all over this site (beautiful writeups and pictures) but Iíd like to see other setups that are less expensive than a $900 powerfilm panel. I donít mind mounting the solar panel permanently to my roof rack so they donít need to be flexible which should lower the price. I am looking for a solar panel that is good at low light conditions (i.e. clouds and light shade cover in a campground.)

    From research Iím leaning towards a national luna dual battery system and some sort of solar panel that outputs enough juice to run a fridge 24/7. Iím assuming a 60 W max panel would be the minimum to keep the fridge going without running down the second battery below its 50% mark. Right now my only experience points to a deep cycle battery. Is there a better battery choice to run a fridge and occasional winch (I have a warn M12000.)

    1. Please post up or comment if you have a permanently mounted solar panel that keeps up with a fridge.

    2. Any good drawings or plans to make a fridge slide that not only extends but lowers? The ones Iíve seen are slick and I prefer not to buy an expensive one or design one from scratch.

    My goal is to install a dual battery setup, solar panel, and fridge slide before my main camping / climbing trip in July to Glacier National Park.

    -Randy

  2. #2
    Join Date
    Oct 2006
    Location
    Anchorage, AK
    Posts
    1,193
    A 60W panel puts out 3.5A under ideal conditions, and then for only ~10hrs/day.
    If you have a fridge that draws 3A, assuming a 40% duty cycle, I'd recommend at least a 120-130W panel.
    If you have no other electrical demands, a ~100 Ah (like a size 27 or 31) battery should not drop below 75% overnight. But what if it is overcast?
    I cleaned the snow off my two 123W panels recently. In late Feb. at 61 deg N. they put out only 0.5-1.0A when overcast, whereas in the summer in bright daylight they put out 10-14A.

    Charlie
    Unimog U500 with Unicat camper; diesel BMW X5 35d, diesel BJ40 Landcruiser and diesel M37

  3. #3
    Quote Originally Posted by charlieaarons View Post
    A 60W panel puts out 3.5A under ideal conditions, and then for only ~10hrs/day.
    If you have a fridge that draws 3A, assuming a 40% duty cycle, I'd recommend at least a 120-130W panel.
    If you have no other electrical demands, a ~100 Ah (like a size 27 or 31) battery should not drop below 75% overnight. But what if it is overcast?
    I cleaned the snow off my two 123W panels recently. In late Feb. at 61 deg N. they put out only 0.5-1.0A when overcast, whereas in the summer in bright daylight they put out 10-14A.

    Charlie
    What type of panels do you use? From basic reading it seems some are affected by temperature more than others. That amerpage difference described above is huge.

  4. #4
    Join Date
    Nov 2007
    Location
    Scottsdale, AZ
    Posts
    1,700
    I have a 55watt Siemens panel on top of my Land Cruiser and it will run my frig without starting the Cruiser. Below is part of a previous post of mine.

    I was a little concerned about the Waeco's high power consumption over the Norcold/Engle when I purchased it. But my real world testing has put me at ease.

    I was down in Mexico over the July 4 with 100* outside ambient temp and inside cab temps of 140* during the day. Running a normal battery, 75% full frig, and a solar panel my Land Cruiser started without any hesitation any time of the day or night over the course of several days.

    I have found that a empty frig sucks a lot more power then a full one on both my Norcold 60 and Waeco CF-50. Both frigs empty will eat up my battery in a surprising short time. I have also found both frigs full on a regular battery will make it through the night unassisted and leave enough power to start the Land Cruiser in the morning.

    For me it is to close to call which frig draws less power. The only thing I know for sure is 33* beverages are very nice
    "Knowledge without experience is just information"--Mark Twain

  5. #5
    Thanks Phil,
    That is the type of experience I like to hear.

    Can anyone comment on their solar setup performance when their truck sits for 4+ days without starting the engine? I would like to hear experience from people who stay in one place for days at a time and have a solar setup that works well.

    Living in California is a plus. Most places I camp are sunny and would provide good light. My favorite place in the witer is Death Valley and I like to camp for 2-3 days without moving.

  6. #6
    This is my first post on this forum.
    I have an AC/DC Norcold 1.7 cubic foot compressor Fridge. It drew 2.7 amps at 12.8 volts when the compressor was running when new. 32 months later it draws 2.45 amps at 12.8 volts.

    I Bought a 130 watt Kyocera panel at the same time as the fridge, and a MPPT charge controller. I noticed when my fridge was plugged in to AC, in 90 degree ambient temps the duty cycle was about 65%.

    This freaked me out, so I added extra insulation the exterior. I built a cabinet around the fridge with ventialtion in mind. I have a small 1 inch 12 volt fan inside the fridge. I have a 24 volt ( running on 12v )40 mm fan under the fridge blowing up on the compressor and cooling fins.

    I find that, with the fridge in the cabinet, fans running 24/7, in 90 degree ambient temps, my duty cycle is under 30%.

    If I turn off the fan inside the fridge, the duty cycle stays about the same, but the interior temps rise by about 5 degrees. If I turn off the exterior fan the duty cycle increases by 5 to 7 percent depending on ambient temps, and amount of door opening and closing.


    I have 2 deep cycle batteries (Crown group 27 115 a/h each). I find that in a sunny environment, with the 130 solar panel flat on the roof, I can use my lap top 3 hours a day, the stereo 6 hours a day, the 7 inch tv 5 hours a night, And run my fridge 24/7 and still have fully charged batteries by about 3 pm.

    Water and beer, not electricity are my limiting factors on how long I can remain camped in one spot without starting the engine.

  7. #7
    Quote Originally Posted by wrcsixeight View Post
    This is my first post on this forum.
    I have an AC/DC Norcold 1.7 cubic foot compressor Fridge. It drew 2.7 amps at 12.8 volts when the compressor was running when new. 32 months later it draws 2.45 amps at 12.8 volts.

    I Bought a 130 watt Kyocera panel at the same time as the fridge, and a MPPT charge controller. I noticed when my fridge was plugged in to AC, in 90 degree ambient temps the duty cycle was about 65%.

    This freaked me out, so I added extra insulation the exterior. I built a cabinet around the fridge with ventialtion in mind. I have a small 1 inch 12 volt fan inside the fridge. I have a 24 volt ( running on 12v )40 mm fan under the fridge blowing up on the compressor and cooling fins.

    I find that, with the fridge in the cabinet, fans running 24/7, in 90 degree ambient temps, my duty cycle is under 30%.

    If I turn off the fan inside the fridge, the duty cycle stays about the same, but the interior temps rise by about 5 degrees. If I turn off the exterior fan the duty cycle increases by 5 to 7 percent depending on ambient temps, and amount of door opening and closing.


    I have 2 deep cycle batteries (Crown group 27 115 a/h each). I find that in a sunny environment, with the 130 solar panel flat on the roof, I can use my lap top 3 hours a day, the stereo 6 hours a day, the 7 inch tv 5 hours a night, And run my fridge 24/7 and still have fully charged batteries by about 3 pm.

    Water and beer, not electricity are my limiting factors on how long I can remain camped in one spot without starting the engine.
    wrcsixeight,
    Great post, thank you for describing your setup. Very interesting to hear about the addition of fans, especially the interior one. How accurate are your numbers above regarding the difference in duty cycle (65% down to 30%) after adding the cabinet and fans? That differential is huge when considering multiple camping days without starting the truck. Did you purchase the insulating cover or did you make your own? Any pictures of the cabinet?

    Thanks.

  8. #8
    Join Date
    Apr 2008
    Location
    Auburn, WA.
    Posts
    4,432
    Quote Originally Posted by Randy88FJ62 View Post
    Thanks Phil,
    Can anyone comment on their solar setup performance when their truck sits for 4+ days without starting the engine? I would like to hear experience from people who stay in one place for days at a time and have a solar setup that works well.
    I once ran my ARB fridge in my driveway full time without starting the rig during a four day weekend.
    It started right up for work.

    The ARB fridge pulls 1.7 amps in fridge mode, so less than the 3 amps stated earlier in this thread.

    Parked last summer on my vacation (I camp in one spot the whole time when camping) the rig did not get started once, and my 60 watt Powerfilm panel kept the stock battery topped off while running fridge duty, light in the roof top tent, ect.


  9. #9
    Randy,

    I didn't exactly have a stopwatch going for the 65% number. The fridge was in a laundry room sectioned off from a garage, in Florida, in the summer. Nearly every time I walked by it, during the interior build of my van, It was on. And that irritated me.

    What I didn't mention is that it is not a chest style fridge like your ARB but a front loading kitchen type. It is designed to be put in a cabinet, as the closeness of the walls causes a convection current and draws more air from under the fridge over the cooling fins and out the top. Without the cabinet this didn't happen and caused the huge duty cycle.

    I have since modified the cabinet for vibration and noise suppression, which also insulates it further from ambient temps. I can post a pic if you like, but it is not really relevant to a chest type cooler.

    It is rare for the duty cycle to raise above 30% now. That is an accurate number. Your ARB is inheritently more efficient being a chest style fridge. I only put mine on a setting of 2(out of 5) and this keeps the interior around 38 degrees. A setting of just over 3 is required to bring this to the 32 degree number, and this increases the duty cycle by up to 15%. For food storage under 40 degs is the magical number, so I keep it at 2. When I have an electrical surplus in the afternoon, I sometimes crank it up to 3 or more, until I no longer have a surplus.

    My solar panel was 710$ in June of '07. An improved one (5 extra watts) is now 362$ here:

    URL="http://store.solar-electric.com/kyso130wa12v.html"]http://store.solar-electric.com/kyso130wa12v.html[/URL]

    While most people think only to get a panel big enough to replace the amp hours they use, batteries should be recharged at rate 5 to 13% of their capacity to make them happy. So even though my panel makes more electricity than I use most of the time, It charges them well below the 5% level, and my 3 cheap wally world dual purpose batteries gave up before 3 years. One gave up in 13 months.

    I now have 2 quality deep cycles, and hit them with a 25 amp charger weekly, and notice they really like that higher current because that night, they hold a higher voltage with the same amount of amps being used. I have a battery monitor as well, which I monitor frequently. The remaining 33 month old wally world battery is kept isolated from the house batteries, and is being used as a starting battery only in the engine compartment.

    Get the biggest panel you can afford, and use fat wires (8 or 10 awg) to the controller and from the controller to the battery(s). The shorter the length the better.

  10. #10
    Join Date
    Jan 2008
    Location
    Fulltime RVer
    Posts
    59

    Default My System

    Solar power is much less difficult than it seems at first glance. Here is my system, most of which I bought from Solar Mike at Slab City and Northern Arizona Solar in Flagstaff:

    $440 Kyocera 135 watt panel
    $250 Kyocera 55 watt panel
    $109 BZ 250 mppt controller
    $240 2 Trojan T105 golf cart batteries
    $50 cables, mounts, misc
    ===========================
    $1089

    I live fulltime in my home-built camper and this system meets all my needs. I also added extra insulation to my Waeco/Dometic cooler. I bought the system with the 55 watt panel first, just to have something, and then when I had the money I added the 135 watt panel.

    I have beaten the crap out of my rig with limbs in forests and the panels look like new, they are essentially indestructable unless you go wheels up. Bob
    1993 F150 4X4 Supercab, Homebuilt Camper, My Fulltime Home

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