Announcement

Collapse
No announcement yet.

Advice on small system to power dsl modem at off grid camp

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

  • Advice on small system to power dsl modem at off grid camp

    Hi everyone. I'm looking for a bit of advice (high level at this point) on a small system at our off grid camp. Here's the basics of what I want to power for now:

    Netgear adsl modem/wifi router, model b90-755044-15
    Raspberry pi model 2 or 3
    An Arduino or two for sensors (motion, temp, door sensor)
    A camera that I have not decided on yet.

    I haven't found specs on power consumption of the Netgear router. It has a 12v 1amp wall wort powering it. How would I measure consumption of this device? Considering the devices I want to power I don't want to use an inverter so I don't think using a kill-a-watt is the right way to measure what it would actually consume running off DC?

    I know 12v systems are taboo around here so assuming I went 24v how do I get back down to 12v to power these? Just step down converters?

    I'd like to be able to monitor battery level and report that over the network so I can monitor from home but I suppose I can use Arduino circuits for that. So I suppose I don't need a network connected charge controller.

    And for what it's worth the camera would likely be setup to just send me stlls (or maybe clips?) So probably wouldn't be streaming over the internet the whole time.

    Since I know location is important this is in the Adirondacks in upstate New York. I get trespassers somewhat often so my goal here is basic remote monitoring capabilities.

    Thanks in advance for any advice,
    Brad

  • #2
    Brad 12 volt systems are fine for small systems and toys, and what you want to do is a small toy size project.

    If you know the voltage, say 12 volts, then all you need to know is the current to find the power in WATTS = Voltage x Current. At worse case 12 volts x 1 amp = 12 watts. However that is only half of what you need to know. What is needed is how many wat hours i sused in a 24 hour day. WATT HOURS = Watts x Hours. So if your equipment uses 12 watts x 24 hours = 288 Watt Hours.

    So as an example if you sed 288 watt hours per day the battery size required is 288 wh x 5 days / 12 volts = 120 Amp Hours or a 85 pound, $200 battery

    Panel wattage depends on location and time of year use with one very important caveat which will sink your ship.The calculation assumes you have full view of the horizon to the south, east, and west with absolutely no shade issues from sunrise to sunset. For a PWM controller PANEL WATTAGE = Daily Watt Hours x 2 / Sun Hours. For a MPPT Controller PANEL WATTAGE = Daily Watt Hours x 1.5 / Sun Hours. Winter Sun Hours in your location is 3.1 Sun Hours if you are lucky. So if you needed 288 Watt hours:

    PWM Panel Wattage = 288 x 2 / 3.1 = 185 watts
    MPPT Panel Wattage = 288 x 1.5 / 3.1 = 140 watts.

    The controller will be 15 amps PWM or MPPT.

    Now get your real numbers and crunch them.

    Lastly all your questions are answered in the this STICKY. One more thing, if I or anyone I know find your system, we will steal it. That bright shiny panel glistening in the sun will get our attention from miles away. Even worse we fly planes looking for stuff to steal.
    Last edited by Sunking; 12-09-2017, 12:46 PM.
    MSEE, PE

    Comment


    • #3
      "One more thing, if I or anyone I know find your system, we will steal it.". You're funny (I mean that in a good way). I've read enough of your posts here and see how much time you invest in helping people so don't at all have the impression that you're a thief. But point taken. I'm very aware of that risk. My TV's and stereo (and liquor) would all be gone. Not really much I can do about that. My place isn't visible from any roads or any other camps or homes so you'd either need to be standing here or as you suggested spotting it from the air.

      Thank you for the info. My main questions were how to measure that Netgear and the whole 12 vs 24 volt thing. You gave answers to both so much appreciated. I had read your sticky a while ago but still had those questions. I'll start researching cameras so I can better determine total usage needs.

      As far as exposure, I certainly have trees but have quite a bit of southern exposure and decent amount East and west. I'm also not afraid to drop some trees if needed. I don't have any neighbors so no issues with keeping trees for privacy sake.

      I do have another question (probably really dumb) I thought of. I assume I should not power these 12v devices directly from the battery but instead would want a charge controller with 12v out that would cut power before damaging batteries? And would turn that output back on when SOC is ok again?

      Thanks again!
      Brad

      Comment


      • #4
        Originally posted by bradmck View Post
        "One more thing, if I or anyone I know find your system, we will steal it.". You're funny (I mean that in a good way). I've read enough of your posts here and see how much time you invest in helping people so don't at all have the impression that you're a thief.
        Your perception is spot on, I am not a thief, just making a point.

        Originally posted by bradmck View Post
        Thank you for the info. My main questions were how to measure that Netgear and the whole 12 vs 24 volt thing. You gave answers to both so much appreciated. I had read your sticky a while ago but still had those questions. I'll start researching cameras so I can better determine total usage needs.
        As stated Power (watts) = Voltage x Current. So if the voltage is fixed at either 12 or 24 volts, then to find power all you need is to measure the current. To make it easy to connect the dots use 24 watts and Voltage as the constants and then factor out the variable Current = Watts / Voltage Do that and you quickly learn 24 watts = 12 volts x 2 amps, and 24 volts x 1 amp. Easy 5th grade math if they still taught math.

        Now that may leave you thinking so what difference does it make if it is higher or lower voltage right? Makes a huge difference in efficiency and expense. Lower voltage = more expense, less efficiency, and more risk or danger. Think of current as water volume flowing. Morre current requires a larger more expensive pipe or larger conductors. Copper is very expensive. More current means more heat and power losses which is efficiency and risk to fire. You get the picture and I will leave you with this. There is a dam good reason utilities use high voltages up to 1,000,000 volts.

        Bottom line is 12 volts is good for small power needs of 1000 watts or less. IMO limited to 500 watts. Today about the largest Charge Controller you can buy is 80 amps. That translates to the largest panel at 12 volt battery is 1000 watts. However at 24 volts is 2000 watts and at 48 volts is 4000 watts. Still not enough to run a home that runs on 240 volts and if you had a 80 amp service is roughly 20,000 watts. Your utility delivers 240 volts at 13,200 volts and at 20,000 watts is less than 2 amps on the utility wiring.

        Point is I do not know the exact power requirements you have, but I do know for fact is less than 20 watts, which is perfect fit for 12 volts. Size matters, ask my girlfriends and wife.

        Originally posted by bradmck View Post
        I do have another question (probably really dumb) I thought of. I assume I should not power these 12v devices directly from the battery but instead would want a charge controller with 12v out that would cut power before damaging batteries? And would turn that output back on when SOC is ok again?
        Not dumb, just ignorant because you do not know yet. We can fix ignorance, but no one can fix STUPID. Some charge controllers have what they call a LOAD OUTPUT Terminal which is for the most part useless because they are very low power of just a few amps. What that LOAD OUTPUT Term really is a Low Voltage Disconnect (LVD) and a LVD is really nothing more than a Relay Contact that disconnects the LOAD when battery voltage reaches a set point of roughly 10.5 volts on a 12 volt system. They have 3 applications.

        1. Low Power Night Light
        2. A driver circuit for an external high power LVD relay like a 1000 watt inverter. .
        3. Low power applications like yours.

        Keep reading and asking questions. Hope you have a good sense of humor. A lot of regulars and a moderator here do not, they traded it for Political Correctness.
        Last edited by Sunking; 12-09-2017, 03:12 PM.
        MSEE, PE

        Comment


        • #5
          "An Arduino or two for sensors (motion, temp, door sensor)"

          You have the best low voltage detector out there. I run my entire camp on an Arduino.

          Comment


          • #6
            Originally posted by PNPmacnab View Post
            "An Arduino or two for sensors (motion, temp, door sensor)"

            You have the best low voltage detector out there. I run my entire camp on an Arduino.
            Actually there is far superior microcontroller called Teensy 3.2 and 3.6 operating up to 180 Mhz clock. They have 32 bit processors and two 16 bit A/D converters with much easier language with no complicated loop timers tying up processing time. Arduino is pretty outdated stuff. If you can program Arduino, Teensy is a easy learn as many commands are the same. No more arrays or loop timers to mess with and waste valuable processor time with. More performance with less or equal cost. Give it a try. I use them to make 16 channel Radio Control Transmitters for aircraft.Basically theTeensy can do everything the Arduino can do in a day before the Arduino gets booted up, plus a lot more things the Arduino cannot do.

            Great support forum too where the developer participates. His name is Paul Stroffregen
            Last edited by Sunking; 12-09-2017, 06:46 PM.
            MSEE, PE

            Comment


            • #7
              The one "Gotcha" might be the voltage when the battery is charging, could exceed the safe operating threshold of the router power supply. I know my linksys has a 12V to 5V regulator module, so I would not worry about mine, but your router and camera, may not like 15V when the battery is charging.

              The other problem is the 24/7 duration of the loads, small loads over a long time, can consume a lot of power. You may have to look at using a pair of 6V golf cart batteries which would yield a 12V 200ah battery.

              So, try to measure your loads, then we can give you accurate bad news of what it will cost. (controller, panels, batteries, voltage converters) Or just use Bear Armor shutters over the doors & windows.
              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


              • #8
                Thanks again for the input everyone. I don't currently have a camera so will need to do some research there as far as power consumption before buying anything. I'm open to any suggestions anyone may have from experience. Nothing too fancy (no PTZ or anything) just a decent day/night cam. Not sure yet if I'd go PoE (need an injector or new switch) or just look for something that takes 12v (or less).

                Sunking - on the Teensy thing... That's very interesting. I have heard of Teensy but didn't realize they jumped up to 32bit and have never played with them. And while I said Arduino they're technically NodeMCUs with esp8266 wifi modules that I've been toying with to make temp sensors and stuff for a home automation hobby. Your use sounds cool as I'm also into RC. I've got a buddy into planes but we're also into "drones". Not the "scary" spy ones at all - we setup tracks and "race" each other (up to 4 of us) wearing FPV goggles. I may have to grab one of these Teensy's to play with. I wouldn't mind hearing more about how you use them for Tx if it's something you like to talk about. Though I realize that's obviously off topic.

                Mike - on the issue of exceeding the router's voltage threshold I think I can deal with that. I'm used to rimacnab gging up voltage regulators (Pololu's and stuff). But good point.

                And honestly this isn't so much about "protecting" my camp. If someone wants to break in they're going to. This is more about knowing who is there and when. I had a recent incident where some trespasser went back on our property and shot 2 does. They cut the tenderloins out and left the rest of the carcass to rot. Pissed me enough off to want to monitor a bit better. My father in law is about a half mile away and could show up and just block the driveway with his truck if nothing else. Part of what I'd do here is some wireless PIR sensors (home-brew) using radio modules to send events to my master NodeMCU (or whatever I end up going with). That way I could get email/SMS/whatever alerts in real time. Those wireless sensors would be micro-solar projects in themselves.

                And just to throw this out there - I know the PoCo is way cheaper, but I have literally no possibility of PoCo power at this place. We run off generator when we're there. Funny I can get DSL but not power. I got advice here a while back about this same camp - I was wanting to do a much bigger system but I haven't done anything with that yet. I'd be content with this for now. I don't mind spending the money on this for a bit of peace of mind. If I ever do the bigger system I may just re-purpose anything solar I do now as a remote camera setup further back in the property or maybe on the mountain peak just as a cool view camera. Too bad Nikola Tesla's wireless power never took off.

                PNPmacnab - I would like to hear more about what you're doing as far as running your camp off an Arduino, but again realize that's off topic so if that's not cool that's fine.

                Thanks again,
                Brad

                Comment


                • #9
                  Originally posted by bradmck View Post
                  Sunking - on the Teensy thing... That's very interesting. I have heard of Teensy but didn't realize they jumped up to 32bit and have never played with them. And while I said Arduino they're technically NodeMCUs with esp8266 wifi modules that I've been toying with to make temp sensors and stuff for a home automation hobby. Your use sounds cool as I'm also into RC. I've got a buddy into planes but we're also into "drones". Not the "scary" spy ones at all - we setup tracks and "race" each other (up to 4 of us) wearing FPV goggles. I may have to grab one of these Teensy's to play with. I wouldn't mind hearing more about how you use them for Tx if it's something you like to talk about. Though I realize that's obviously off topic.
                  Maybe off topic, but it is your thread and we can talk about it all you want. The Teensy is quite a an upgrade. Given the price is the same makes it a No Brainer. You can still use Shields to talk with whatever you want. I used the Teensy 3.2 for my RC Transmitters. I can do anything any other Transmitter can do and more up to sixteen channels. The great thing the Teensy has a Library for the 16-channel PWM. You just use that to feed a TX module you buy. You use the same Arduino IPE app. Many of the commands are the same. More importantly is the screwed up Timer Loops and Array are gone. There is a ton of Library's to use including the 16-Channel PWM Library. To output a channel is easy:

                  // PPM Output, pin 10, to TX Radio Trainer Port. 1 to 16 channels max.
                  PPMOut.write(1, dZ_THR); //Channel 1 in uS
                  PPMOut.write(2, dZ_AEL); //Channel 2 in uS
                  PPMOut.write(3, dZ_ELE); //Channel 3 in uS
                  PPMOut.write(4, dZ_RUD); //Chanel 4 in uS
                  PPMOut.write(5, Gear); //Channel 5 in uS
                  PPMOut.write(6, Aux); //Channel 6 in uS
                  ..
                  PPMOut.write (16, Buger Digger); //Channel 16 in Us

                  I sample with 13 bits or 8191 resolution. Smoothing a Joystick is super easy, no arrays, just a simple Setup command:

                  analogReadAveraging(32);// Average 4, 8, 16 and 32 readings, smooths stick input and jitter. No Delays or arrays.

                  You get the picture. There are a ton of projects on the PRJC website and a great Forum with a lot of experienced code writes. I am not a code writer by profession, and if I can do it, you can. I did it both ways with Arduino which was a nightmare. Teenswy was easy. Anything you can do with any Transmitter, you can do with the Teensy. Does not matter if it is a 3-channel car, 16 channel giant scale plane, or a flying bomb drone. Mine has a full display and holds 24 models.

                  OK back to your project. I got a design I know full well that will work for you. In fact a bit of an overkill, but will run you camera and modems no problem at all, and give you some of the extra fluff you want to run a TV and DVD player, charge cell phones, and can grow as needed.

                  The first thing to do is find a panel you know you can get today and down the road when and if you expand. You want a panel with a wattage of 200 to 250 watts.One with 72 Cells, or 60 can work. That is pretty easy to do now days.

                  The next thing will take some consideration of how large you might want to grow. That greatly effects the size of the MPPT Charge Controler you choose and battery voltage. Minimum requirement with a 200 watt panel is 15 amps, and 20 amps with 250 watts. Example if you bought say a Morningstar TS-MPPT-45 amp would allow you to grow to 600 watts, and 200 watt panels are a perfect fit for that goal. Roughly here are the limits for a 12 volt battery

                  80 amps @ 1000 watts
                  60 amps @ 750 watts
                  40 amps @ 500 watts
                  20 amps @ 250 watts
                  15 Amps @ 200 watts.

                  There is a catch here you need to consider. A good 15 amp MPPT controller wil cost you roughly $175 and goes up to around $600 for an 80 amp model. So be real with future growth, as it gets expensive. However there is a nice surprise. What I just quaoted you only applies to 12 volt battery. Those exact same controller power input doubles if you use 24 volts, and doubles again at 48 volts. So that 40 amp controller with 12 volts can only handle 500 watts goes to 1000 and 2000 watts with respect to 24 and 48 volt battery.

                  Lastly batteries. Take my advice here and just use Golf Cart Batteries. Again like the panels use the same make and model. Golf Cart batteries are 6 volts @ 200 to 250 AH. You would need 2 for 12 volts, 4 for 24, and 8 for 48.

                  So here is the bare bone minimum setup for you.

                  Panel Wattage = 200 watts
                  Morningstar Sun Saver MPPT 15 Amp Controller. Note this is a gotcha. Max is 200 watts @ 12 volts and 400 watts @ 24 volts. However the least expensive good option.
                  Pair of 6-volt golf cart batteries. For your first set buy them from Wally World, Sam's, or Costco and keep the receipt. Easy warranty replacement. Next pair you can upgrade to Trojan, no not the rubbers, the batteries.


                  Check it all out and ask questions.
                  MSEE, PE

                  Comment


                  • #10
                    Sunking - I want to thank you for all this information. I've been extremely busy with work so haven't had much time to research any of this yet let alone reply back here. But I wanted to post a quick thank you. I will do some research on what you laid out here - it sounds like the right direction to head. I gotta think about the growth potential - I see you're right in that the charge controllers jump up real quick. I'll be back after some homework.

                    Comment


                    • #11
                      Originally posted by bradmck View Post
                      Sunking - I want to thank you for all this information.
                      You are welcome. Merry Christmas.

                      MSEE, PE

                      Comment

                      Working...
                      X