Announcement

Collapse
No announcement yet.

New Garage--How to power garage door openers

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

  • New Garage--How to power garage door openers

    Forum Sages:

    I am now to solar and this forum (it is great!) and have been reading about off-grid garages but cannot find an answer to some basic questions. This is my first solar installation and want to get it right so sorry for newbie questions.

    I built a two car garage on my property that is too far away from line power so solar it is. I had two Liftmaster 8500 garage door openers installed. The openers are meant to be installed with 120 v line voltage, with an optional battery backup. The opener motor is 24 volts DC. You can buy a battery backup that plugs into the unit. I have not purchased the battery backup units.

    8500 Electrical specs:

    24 volt DC motor
    line Voltage: 120V AC, 60 Hz.
    Wattage: 120W.
    Current Rating: 2.7A.

    I called the Liftmaster folks and asked if I can connect a 24 volt battery bank (charged by solar) directly to the unit and not use 120 volt line voltage. They said "this will nullify the warranty" He suggested i connect the system to 120 volt power and purchase the battery back up unit. So i considered building a solar system with an inverter to run the openers. I would power the garage lights with DC LED's.

    However, in reading the forum, someone said it was not a good idea to invert the DC solar system to 120 volts for garage door openers since the power draw on the idle system would be too great.

    So a few questions:

    1. Do I Build a solar system with 24 volt battery storage and run the garage doors (and five 10-watt LED lights) directly with 24 volts? (i don't care about the warranty if it is best to directly connect)

    or do I Build a solar system with 12 volt storage, invert to 120 v, buy the Liftmaster battery backup, and hook up the Liftmaster to 120V?

    2. I live in Oregon, 70 miles east of Portland, that gets decent sun. The doors would run maybe once per day. Lights even less. I figured a system as follows:

    100 watt solar panel
    Sunforce 60022 30 Amp Solar Charge Controller
    Amstron 12v battery, 55Ah, 660 Whr (2 if 24 volt system)
    Inverter (not sure what size to get or if needed)

    Your comments and sage advice is most appreciated!

    thanks!

  • #2
    to charge a 24V battery, you need a 32V PV panel (allows for wire losses, battery equalization, hot day losses) Most of the 150w and less panels, are for 12V systems only.

    You won't need a lot of power, but the batteries (two 12V in series) have to be able to supply the DC motor surge, what size battery does the factory rig come with ? You need to at least match that size

    So, with a 200W 40-60v panel, a Morningstar MPPT 15A (about $200) controller
    http://www.solar-electric.com/invert...umpsochco.html and a battery a bit over the single factory battery ah rating should be OK (with all the fuses and such too) you should be good to go. But don't expect to run a shop vac to clean things with, or recharge car doodads from a small system.
    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


    • #3
      I would do the 24v, because it's more elegant, and I'm stubborn. I wouldn't want Liftmaster telling me that providing superior power to the system voids the warranty.

      I expect that 9 out of 10 times the company coming out to do warranty repairs would say nothing about a 24v setup. They want to do the fix and get paid. They don't want to get between the owner and Liftmaster in an argument.

      If I had a generator in your situation, I might hook the opener up to it for a warranty service call so it's running off 120v.

      Garage door opener are reliable in the early part of their life. I've purchased probably over 100 in my life (spec building), and I don't recall a warranty repair. But this assumes you do the 24v setup correctly.

      On the other hand, perhaps the continuous inverter draw doesn't matter much on a system where optimal energy use isn't important.

      What are your yearly high/low temps? I know you're far enough east to have much different weather than Portland. (I use to store my camper across from portland in Vancouver Wa). Do you have temperature constraints on batteries?

      Edit: You are close to a situation where you could use a two 12v starter batteries. Your application is similar to automotive power use.

      Comment


      • #4
        Thanks for replys

        Great info from both of you. thanks!

        I was not aware of requiring 32V PV's for a 24 volt system.

        I was also not aware that i should use a MPPT type controller. I had assumed a PWM controller was appropriate.

        I cannot find the backup battery specs on the Liftmaster website so will call them to obtain the Amp-Hour rating. Do i need data other than amp-hour?

        My min/max average temps in Mosier Oregon are 28 deg F/82 deg F.

        Based on your input, I will pursue building a 200 watt/24 volt system, with MPPT controller, with two 12 volt batteries in series, using a MPPT controller. I will find out the battery size to use based on Liftmaster's backup battery specs. i will run the openers with 24 volts dc, not 120 V AC.

        any other comments and advice is very much welcomed.

        Mike

        Comment


        • #5
          Originally posted by MosierMike View Post
          Great info from both of you. thanks!

          I was not aware of requiring 32V PV's for a 24 volt system.

          I was also not aware that i should use a MPPT type controller. I had assumed a PWM controller was appropriate.

          I cannot find the backup battery specs on the Liftmaster website so will call them to obtain the Amp-Hour rating. Do i need data other than amp-hour?

          My min/max average temps in Mosier Oregon are 28 deg F/82 deg F.

          Based on your input, I will pursue building a 200 watt/24 volt system, with MPPT controller, with two 12 volt batteries in series, using a MPPT controller. I will find out the battery size to use based on Liftmaster's backup battery specs. i will run the openers with 24 volts dc, not 120 V AC.

          any other comments and advice is very much welcomed.

          Mike
          I would suggest the option of running a 40 amp 120volt power circuit out to the garage and see which will cost more over a period of 8 years. During that time you will have to replace those batteries 2 times so use a value of 3 times the cost of the first set plus the cost of the MPPT CC, solar panel and inverter. I could be wrong but you might be surprised to see which one costs less.

          Comment


          • #6
            The opener backups use two UPS type batteries. On the order of 5ah each.

            Maybe start with smaller/cheaper batteries with the idea that they will have a short life as you figure out usage. 2 x 20ah is ~$80 for security system batteries claiming to be deep cycle.

            Personally, I would not spend more than $100 for a charge controller for this type of system. The key is to keep the cost down, while not buying junk.

            Comment


            • #7
              Originally posted by MosierMike View Post
              8500 Electrical specs:

              24 volt DC motor
              Wattage: 120W.
              This all I need to know. Immediately tells me a 24 volt 20 AH AGM battery. Problem is finding a single 100 watt panel with a vmp of 36 volts. But no problem, just pay more for 2-12 volt 50 watt battery panels wired in series and a 5 amp 24 volt PWM charger. Hell as infrequently as it will be used with AGM you could go as low a 50 watts total with 2-25 watt panels in series. Nothing to it.
              MSEE, PE

              Comment


              • #8
                More thanks

                you have all provided excellent input. thank you. i am feeling the solar love. i will report back on my project.

                Sun Eagle, i really would like to run line power. i will double check the cost comparison now that i have some guidance on what to buy for a solar installation. The situation requires a new power drop/meter from a pole, underground conduit/wire for 550 feet, new panel. and not easy ground to trench. And as a civil engineer i love the idea of digging trenches but also enjoy playing electrical guy. Maybe i have electrical engineer envy. You electrical folks were always the smartest in engineering school!

                Comment


                • #9
                  Originally posted by MosierMike View Post
                  you have all provided excellent input. thank you. i am feeling the solar love. i will report back on my project.

                  Sun Eagle, i really would like to run line power. i will double check the cost comparison now that i have some guidance on what to buy for a solar installation. The situation requires a new power drop/meter from a pole, underground conduit/wire for 550 feet, new panel. and not easy ground to trench. And as a civil engineer i love the idea of digging trenches but also enjoy playing electrical guy. Maybe i have electrical engineer envy. You electrical folks were always the smartest in engineering school!
                  Based on the 550 ft distance, power meter and pole the cost will add up. The input from Sunking and donald indicates you might get away with an inexpensive solar battery system that meets your needs.

                  Most people forget to do the comparison and just jump into the solar battery system. I just try to make sure people don't rule out the power drop option.

                  Let us know what you end up doing and how it works out.

                  Comment


                  • #10
                    Originally posted by Sunking View Post
                    This all I need to know.
                    Are you remembering that the receiver in these units are always on?

                    Edit: Also, the photoelectric system is always on when a door is open. Think about it, it really is a 24/7 on device that is going to need to be measured. Two units could be drawing 20 watts idle. That would make 40ah of storage much too small, and panel size becomes a more important question.

                    Comment


                    • #11
                      Originally posted by donald View Post
                      Are you remembering that the receiver in these units are always on?
                      They use almost nothing in terms of power and can be ignored. If he is worried about add another 5 watts to the panels. The battery and panels are way over sized and made to match the motor. A single charge can operate the doors 2 hours and at 20 seconds per cycle is around 360 times to 50% DOD. Who gives a crap about a RX?
                      MSEE, PE

                      Comment


                      • #12
                        Originally posted by MosierMike View Post
                        And as a civil engineer i love the idea of digging trenches
                        I love it *only* if I am doing it with a excavator/backhoe. (or maybe a trenching machine - haven't driven one of those)
                        If I'm doing it with a shovel, forget it.

                        Comment


                        • #13
                          Originally posted by Sunking View Post
                          They use almost nothing in terms of power and can be ignored.
                          I survey I found puts the phantom load typically between 5-8 watts. 5 watts x 2 certainly puts him under 50% DOD in winter with 40ah of battery. Mikes two 55ah batteries in his original list is probably about right.

                          Comment


                          • #14
                            Originally posted by donald View Post
                            I survey I found puts the phantom load typically between 5-8 watts. 5 watts x 2 certainly puts him under 50% DOD in winter with 40ah of battery. Mikes two 55ah batteries in his original list is probably about right.
                            What phantom load? The receiver?
                            The receiver should be using 1 watt or less.

                            Your math needs work. 10 watts x 24 hours = 240 watt hours. A 24 volt 40 AH battery has 960 watt hours. 240/960 = 25%

                            He stated he wants to use straight battery at 24 volts, and the motor draws 120 watts which means 5 amps at 24 volts. On a AGM battery can draw up to as high as a C/4 current. Minimum battery size to run the motor = 5 amps x 4 hour rate = 20 AH. Now if the receivers really used 10 watts, then yeah he would need at least a 40 AH battery. Bu tI have been into ham radio a long time and non eof my radios use that much power and that is with scanners, processors, and audio amps which he does not have. A cell phone does not even draw that much power in Rx mode clipped on your belt. In talk mode 2 to 3 watts with a .25 watt in Tx power. I find 5 to 8 watts a very hard pill to swallow for a single integrated circuit receiver.
                            MSEE, PE

                            Comment


                            • #15
                              Certainly the receiver portion could operate at 1W. But why would you assume they bothered to do a proper design? The units need to be measured, both at full idle, and with the door open.

                              Your figures show 40ah doesn't work when temps can reach freezing in winter. The batteries have 32ah at 0C when the battery is new. Without the certain ability to add back the 10ah every day, on some days the battery will fall below 50%. Below 50% charge the battery will freeze at 0C.

                              Batteries can be used in his climate only if he can always keep the charge always above 50%.

                              Near the equator he probably could get away with 40ah and a considerably smaller panel.

                              Comment

                              Working...
                              X