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Solar questions for 2009 DM T@B

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  • rtolanrtolan Member Posts: 22
    I have a 2009 T@b with a 2 way frig. I would like to add 2 , 100 watt solar panels to the roof to power the frig since I rarely camp plugged in to 110 while camping. Does anyone have experience on how long the solar will keep the battery charged to run the frig assuming the panels are faced into the sun. I live in Colorado so usually plenty of sun. Would I be better with portable panels? How about replacing the frig with a 3 way? Thanks for any help.
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  • pthomas745pthomas745 Moderator Posts: 3,961
    How many amps hours does your battery have?  How many amps does your fridge use? 
    2017 Outback
    Towed by 2014 Touareg TDi
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  • rtolanrtolan Member Posts: 22
    I have the refrigerator manual but not sure of your question. Per the manual it says a Rv battery provides 90 a/h min. But I don't see how much the frig uses. ???
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  • pthomas745pthomas745 Moderator Posts: 3,961
    edited March 2018
    You need to look at your specific battery to determine the amp hours..but 90A/H sounds about right.  Look at the fridge manual to see if the specifications include "amp draw."   The 2 way fridges are fairly efficient on electrical use. 

    These are general numbers:

    IF you have a 90 amp hour battery, you essentially have 45 amp hours to use.
    IF your fridge uses 3 amps per hour, you can run it for 15 hours (approximately) before your battery uses up the 45 amp hours.

    I would say your 200 watt panel should keep up with that sort of use just fine.  IF you are in the sun.
    2017 Outback
    Towed by 2014 Touareg TDi
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  • rtolanrtolan Member Posts: 22
    You have been a huge help. Thank you. I will do more research on the amp usage of the frig. I use solar lights in the trailer and only use battery to start the propane furnace so I hope the 200 watt panel will do it. I also have a yeti 400 that I bring . Will the solar panels be able to recharge the yeti also or do I need a special portable solar panel just for that?
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  • pthomas745pthomas745 Moderator Posts: 3,961
    I don't know enough about Yeti to comment on that.
    I did dig around to find some older Norcold 2 way fridge manuals that had amp draw listed, which is where I came up with that 3 amp hour draw number.  You need to get specific with the model number of your fridge and the size of your trailer's battery to make those IF numbers more specific.
    2017 Outback
    Towed by 2014 Touareg TDi
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  • rcuomorcuomo Member Posts: 319
    edited March 2018
    If your T@B has the Interstate dual purpose HD24-DP battery it is rated at 100 reserve capacity minutes and that converts to 41.67 amp hours.  According to I think Jenn Grover's power consumption chart the 2 way fridge draws 3.60 amp and the 3 way fridge draws 3.0 amps.  Hope this helps.
    ‘18 Tab 320S- mfg’d 4/17, acquired 9/17
    Spare & bike rack on tongue, Renogy 100w suitcase connection, cargo & door nets, sway bar, wired rear camera, Norcold aux fan, front window protection, frame mounted sewer & water hose storage, Krieger 1500w inverter w/100Ah LIFePO4.
    ‘17 Honda Ridgeline RTL-E- 5000# tow cap, 600# tongue cap
    ‘20 Honda Pilot Elite- 5000# tow cap, 500# tongue cap
    Huntington LI
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  • rcuomorcuomo Member Posts: 319
    edited March 2018
    I stand corrected.  According to the Norcold installation manual the 3-way draws 11.7 amps @ 12v.  That would indicate 3.5 hours of use on a fully charged Interstate battery, slightly more with a 100 amp battery.

    DC Operation (3-way and/or fan models only)
    12 volts DC voltage
    (11.5 volts min. - 15.4 volts max.)
    Current Draw
    11.7 Amps at 12 Volts DC
    13.6 Amps at 14 volts DC

    AC Operation
    120 volts AC voltage
    (108 volts min. - 132 volts max.)
    Current Draw
    1.4 Amps at 110 Volts AC
    1.5 Amps at 120 Volts AC
    ‘18 Tab 320S- mfg’d 4/17, acquired 9/17
    Spare & bike rack on tongue, Renogy 100w suitcase connection, cargo & door nets, sway bar, wired rear camera, Norcold aux fan, front window protection, frame mounted sewer & water hose storage, Krieger 1500w inverter w/100Ah LIFePO4.
    ‘17 Honda Ridgeline RTL-E- 5000# tow cap, 600# tongue cap
    ‘20 Honda Pilot Elite- 5000# tow cap, 500# tongue cap
    Huntington LI
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  • mash2mash2 Member Posts: 581
    I ave an 06 T@B with 2 way fridge.  My working number for it is about 2.7 amps per running 12 hours per day (depends on how cold you keep it - mine runs at the midpoint coolness -- and the outside temperature (that will influence how long it runs.  when estimating my solar requirements, I assumed about 35 AH per day for the refrigerator.    

    The second variable is the capacity of your battery.  With a 100 AH battery, you should plan on no more that 50 AH of power )since you shouldn't let the battery go below about 50 percent of total capacity or the life will be significantly reduced.  With this, you would get a couple of days before the battery meets rrawdown issues.  

    Adding solar panels adds a third variable... solar yields to the battery.  Panels will add capacity back to batteries (up to the total capacity of battery).  Depending on time of year and location, you can estimate the yield on solar panels based on location and time of year.  In northern california, during summer months I can count on up to 71 Amp hours of yield from my solar panels (see http://www.where-rv-now.com/Notes/Solar/index.php) for estimate of yields from different solar systems.  I have 200 AH of batteries (2 1-00 AH battery.

    How long can I go in March?
    I have 2-way fridge (uses about 35AH per day)
    Furnace and fan (use about 10 AH per day)
    I have 200 AH battery capacity
    Solar panels are 136 Watt -- 16.9 AMP solar panels
    I'll assume that the days are all clear (reasonable assumption in northern California -- but your location may not be clear -- adjust the solar yield to reflect solar time lost to cloud cover.  

    easy to calcualte

    BASIC Formula   Solar yield  - Appliance use =  net AH used daily
                                        If net AH used daily -s [positive -- capacity is not a problem.  
                                        If net AH  use is greater negative, divide usable battery AH (1/2 capacity of batteries) by
                                        Net AJ -- this converts to number  of days before additional charing needs to occur.  

    My system, for Example
    100 AH         -- Starting capacity  100 AH (1/2 of my battery capacity)  
    47.7 AH        -- Camping in Northern California (17.5 degrees latitude) number from solar calculator referenced
                             above
    45 AM         -- Daily estimate use for fridge, heating, fan use for the day    35AH for fridge and 10 for fan and
                            heater on DM T@B
    I should not run out of battery (I'm using about as much as I replace daily.  
    If it is cloudy all day, I could last 2 1/2 days without any solar.  
    If it is cloudy half of each day, I would be able to generate 25 AM of power and could last up to  5 days (I"m using up 20 AH of battery that is not replaced each day that it is cloudy for a half of a day).  

    In practice this has been my experience.  In summer, with use similar to yours, 200 AH battery capacity with reasonable use, I went for a couple of  months without any need to hookup.  I did drive between locations so the tow vehicle did add some power for the batteries.  

    In January/Februar the fridge use went down but heat went up significantly.  Still worked for a couple of week trip, but reduced solar made it very tight.... 

    Hope this helps
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  • ColoradoJonColoradoJon Member Posts: 415
    @mash2 - your 136 watt solar panels can produce 16.9 amps?  What brand are they?
    Jon & Angela | Florissant Colorado | 2017 Outback S
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  • rtolanrtolan Member Posts: 22
    I knew this was the right place to come with my questions. You folks are amazing- both knowledgeable and willing to share. I plan on going with the two, 100 watt panels and will let you know what I learn. THANK YOU.
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  • mash2mash2 Member Posts: 581
    Thanks for the catch ColoradoJon.  The correct specification is 16.9 Volts not amps.  The solar yield table uses the voltage of the panel.  The AMP yield for my solars are 5.1 AMP each.  The Voltage at PMAP (Amp) is actually 16.5.  The theoretical max panel apt is about 6.3 Amps at solar noon.  Sorry for the error.    
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  • ColoradoJonColoradoJon Member Posts: 415
    @mash2 - dang, I was hoping that they did produce 16.5aH!
    Jon & Angela | Florissant Colorado | 2017 Outback S
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  • rfuss928rfuss928 Member Posts: 1,021
    edited March 2018
    This will be our eighth season traveling with SUNT@B.  Although we generally opt for sites with power when available, we rely on our solar to allow us to choose to stay where ever, when ever.  This is especially helpful in western states and in or near National Parks.
    Our 136w of solar will produce about 35Ah on a bright sunny day with the T@B well positioned for insolation.   This will just keep up with the electric frig requirements and a little lighting.  On less than ideal days or locations we will be counting on the 150Ah of AGM batteries to carry us through.  Late last season I added an 80w portable panel to our kit for those times when just a little more will allow us to extend our stay or worry a little less about challenging solar conditions.
    Generally, we rarely have any concerns about our batteries and available power since adding the solar and consider it one of our best modifications.
    Your camping style and locations will be the only sure validation of choices.  200w is well above the general guidelines offered by T@B owners through the years and should provide a good starting point for your solar power system.
    Have Fun!!
    Bob





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  • rtolanrtolan Member Posts: 22
    Thanks Bob. From you and others I feel confident in my choice. As you say, camping experience will tell the tale. BTW, I have your "sunt@b" in the Q layout version-all yellow with white trim. It's gotta be a sun magnet☺️. Thanks again to all.

    Roberta
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  • rtolanrtolan Member Posts: 22
    My solar installer is recommending 2, 100 watt solar panels made by Windy Nation. The reviews look good online. Has anyone had experience with this brand? Grateful for all of you experienced solar folks out there willing to share. 
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  • pthomas745pthomas745 Moderator Posts: 3,961
    edited March 2018
    I have a Windy Nation controller and extension cables.   The controller and cables are well made and have worked fine.  Personally, I think solar panels are commodities, pretty much interchangeable.  The Suaoki flex panel I bought seems identical across the board.  (I bought it because it was on sale.)

    Look at their warranty information, and, of course, the Amazon reviews on how well they support the product.  One of the Amazon reviews on the Windy Nation 100 watt panel has pictures of a Tab with the panels mounted on the roof.



    2017 Outback
    Towed by 2014 Touareg TDi
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