Living Off Grid

Discussion in 'Tech: Batteries, Charging, Alternative Energy' started by Jbordinhao, Mar 17, 2019.

  1. Jbordinhao

    Jbordinhao Member

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    we currently have a GMC Sierra and a travel trailer. Definitely going to purchase with the Rivian R1T or Tesla’s pickup truck. Trying to plan a little in cost of solar. If I was off grid and the truck batteries were dead, could I plug in the solar panels directly to a charge controller and then to the truck to charge up? I understand it won’t happen in a few hours. But what’s the best way to live off grid with solar and the R1T?
     
  2. Ray

    Ray New Member

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    Jansen,

    You will need lots of solar cells! I have a new system and have 45 cells to create a 15KW system, which would take days to fill the biggest 180KW size battery on Rivian R1T.

    upload_2019-3-18_13-2-43.jpeg

    upload_2019-3-18_12-57-13.jpeg
     
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  3. Hmp10

    Hmp10 Well-Known Member

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    It takes 33 kWh of energy to add 100 miles of range to a 2018 Tesla Model S. Using as a comparison the range a Tesla gets from its 100 kWh battery (315 miles) and the range a Rivian gets from its 105 kWh battery (240 miles) -- due to the greater weight and lower aerodynamic efficiency of the Rivian -- it would take a bit over 41 kWh hours of energy to put 100 miles of range on a Rivian. It typically takes four panels one hour to produce one kilowatt of electricity in ideal conditions. That's either a LOT of hours or a LOT of solar panels to put 100 miles of range on a Rivian. And that's assuming weather conditions are optimal for solar generation. If you live somewhere with a lower solar factor than Las Vegas, the numbers just go higher.
     
  4. Jbordinhao

    Jbordinhao Member

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    So what your saying is i will be camping for a few days haha.

    I would have to have a pretty big battery bank as well correct? What would be ideal is to drive majority of the day. Find a place to stop rest off grid. Charge up via my solar+battery bank and have an adequate charge to continue on my journey.
     
  5. Hmp10

    Hmp10 Well-Known Member

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    It would have to be a very long rest stop to get any significant additional range from portable solar panels. Rivian is working on an auxiliary battery pack for extending range in out-of-the-way places. There's a thread about it elsewhere on this forum.
     
  6. Cactusone

    Cactusone Member

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    It’s like filling a 5 gallon bucket with rain water. First it has to rain (sunny) and then you have to wait a long time.

    There is a magnitude disconnect that a lot of people have on how much power is stored in these batteries and how much power comes from a standard solar array. When this technology becomes more mainstream it will make it clearer to most on what is low density vs high. A small solar panel/wind turbine is really a joke, it’s like eating soup with a tooth pick.
     
  7. ajdelange

    ajdelange Well-Known Member

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    You can do rough calculations as follows:

    A Rivian has a probable range of 400 mi and a 180 kWh battery. Thus range is about 2 mi per kWh. A panel will produce about 1/4 kW AC in full sunshine. Thus a 10 kW (AC) system is about 40 panels. There are are about 5 hours of equivalent full sunshine in the temperate zone in the summer and about 3 in the winter. Thus, on average you can charge about 5*10*2 = 100 miles per day in the summer with a 40 panel system and 3*10*2 = 60 miles per day in the winter.
     
  8. binny

    binny Member

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  9. ajdelange

    ajdelange Well-Known Member

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    Don't look at it as being beaten down by the other members. Look at it as being beaten down by the laws of physics to which you, the other members, and even Elon Musk are subject. Assuming the solar array to be about the size of one panel, assuming that the 3-motor cybertruck will have a battery of about the same size as the Rivian and using the ROM numbers from No. 7 you would be able to charge about 2.5 miles per day on average on a mid latitude coastal day in the summer and about 1.5 in winter. Wow!

    Credit Elon for some new battery, drag coefficient and motor efficiency which doubles those numbers to 5 and 3. Goose bumps!

    Elon is not only good at engineering, he is good at marketing and as this scheme has demonstrably taken in at least one person it's going to take in others too. Besides which, as the Rivian has a camper/cook top option the Cybertruck has to have one too. I don't care what people say - these two vehicles are in competition.
     
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  10. Hmp10

    Hmp10 Well-Known Member

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    Well, maybe not all that good. It seems that he did not understand that the ability of those glass panels to flex and disperse energy when a steel ball was dropped on them would not yield the same result when the panels were mounted in a rigid door frame that did not allow the flexion.
     
  11. ajdelange

    ajdelange Well-Known Member

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    Clamping the edges doesn't prevent flexion. But it changes the way the forces between the support and glass are distributed. Were the issue stress at the edges, that's where the fault(s) would have occurred. Note that the samples in the drop test were clamped to the frame in 8 places and that the ball dropper adjusted those clamps between "tests'.

    We'll never know what happened with those windows. I'm quite suspicious that what happened was intentional. If they did not want the windows to break they would have done the demonstration test 184 times off line before doing it in front of the world to be absolutely certain there would be no such failure. The question is, of course, why they would want to put this failure before the public and of course I have no ideas about that so perhaps I am way off base in my suspicions but the whole show gave me the feeling that something wasn't quite kosher.
     
  12. electruck

    electruck Active Member

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    Solar might not generate enough charge to add meaningful driving range but it could be used to offset parasitic drains such as when parked at an airport for extended periods (think weeks or months at an airport) or the charge consumed by the camp kitchen when enjoying the wilderness for extended periods (I think Rivian indicated roughly 10% drain over a week). But for the latter scenario, Rivian will also have the aux battery for the R1T. Those scenarios aren't meaningful to me but they could be to some.
     
  13. ajdelange

    ajdelange Well-Known Member

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    #13 ajdelange, Nov 23, 2019
    Last edited: Nov 23, 2019
    A single panel produces about a quarter of a kW in full sunshine and as summer (winter) full sunshine is 5 (3) hour-equivalents per day we are talking about 1.25 (0.75) kWh available for vampire drain etc.
     
  14. Hmp10

    Hmp10 Well-Known Member

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    A lot of other people are suspicious, too. I certainly would not put such a ploy beyond Musk if he thought it would be of benefit to him. However, I watched the live streaming real time before there were any opportunities for edits, and he seemed truly to be thrown off balance when those windows broke.
     
  15. ajdelange

    ajdelange Well-Known Member

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    I thought he seemed off balance throughout the whole thing.
     

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