Battery powered chicken coop door with solar charger

Discussion in 'The Projects Forum' started by beccasev, Mar 24, 2013.

  1. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    Hi! I’m trying to build an automatic chicken coop door. I’ve seen several posts here about it, but none have answered my specific questions. I know a little about electricity, but haven’t worked with small circuits like this. I also don’t know how to calculate the amps of the system or anything technical like that. I know basic housing electric and that’s about it. (Oh and theatrical electric, but that’s a different story.)
    This is what I am proposing. I want the system to be run by a 12v battery that is trickle charged by a solar panel. I have a drill to do the work. Running power to the coop is out of the question. Here are my specifics.
    I have a 1.5 watt solar battery charger from Harbor Freight. It’s meant to keep batteries from dying, not to charge them. I hope to use this to keep the battery maintained. (I do have access to an ac charger for 12v batteries as well if I need to recharge the battery that way. I’m hoping for mostly maintenance free running here.) How do I figure out if this is enough to keep my battery charged?
    I have a 12V 5aH sealed rechargeable battery. Is this big enough?
    I have a 12v 16a timer.
    I have two limit switches that are SPDT, “rated 5A at 125/250VAC”. Will these work with a DC system? I’ve seen a lot of “harvest switches from old equipment” advice, but it’s easier for me to buy what I need.
    I have a small 3.6V drill that is normally used with a battery that I intend to hardwire to my system. No idea on amps on that one.
    I’m pretty sure I need some DC DPDT relays, but I am not sure about that. Are AC and DC relays the same? I do have a 30/40a SPST automotive relay, but I think it’s the wrong kind now that I have done some more research.
    I want to put a fuse on it just in case. I have an inline fuse holder rated 250VAC, 10A and some 5A fuses to fit it. Do my fuses have to match amperage to the holder? Or does it need to have a bigger amp rating since the timer is a higher amp?

    As far as I can tell, I have two options for this system. 1) The drill goes one way to take door up on a cable and then reverses and goes the other way to put it down. Or 2) the drill only goes one way, is mounted to a disk with a rod attached to the door. When the disk rotates 180 degrees, the door is open, when it rotates the final 180 degrees at the end of the day, the door is back down.
    I don’t care which way it works, as long as the wiring is relatively simple and straightforward with easy to find pieces. I’m not interested in computer boards like I’ve seen some others do. I just don’t really know what all I need, or if all my pieces are rated correctly and will fit together safely. (I don’t want any fried chicken ahead of schedule!) I’m cobbling together several different systems because of our particular restraints (money and no AC current being the biggest) and because no one out there seems to have done this before. At least not that they have shared.
    So far, my circuit as I have it figured out is this. The solar panel is run into the coop and connects to the battery, charging it. The positive comes off the battery, goes through the fuse, and then goes to the timer. The negative comes off the battery and goes straight to the timer. The feed then goes to the bottom switch which tells it the door is closed, then to the top switch that tells it when the door is open, then goes to the DPDT relay, then goes to the other DPDT relay, which sends it to the drill. Is that correct? Could the last relay be a SPST or does it really matter if it is double and I only use it as a single? Or, as I think some more about it, do I have it wrong and each relay gets its own switch to control and then goes to the motor? The latter switch/relay setup seems more logical to me, as the power would then go through the completed circuit and activate the drill.
    Am I missing any pieces? I've seen some talk of diodes, but I don't really know what they do or if they are necessary.
    Any advice would be helpful, even if you can only help with part of it. I would love to learn more. Thanks!
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,049
    3,244
    AC and DC (coil) relays are different. It's possible to operate AC coils off DC at a lower voltage but not recommended unless you already have the relays.

    That solar panel should be sufficient if you only operate the door twice a day. How will you maintain the drill battery?

    As far as your connections, it's rather difficult to determine exactly what you are proposing from your description. Post a wiring diagram (a picture is indeed worth a thousand words).
     
  3. whatsthatsmell

    Active Member

    Oct 9, 2009
    102
    4
    So you're intention is to run the 3.6V drill motor off the 12V battery?

    The bad news is it won't last long. The good news is it will open the door really, really fast before it burns up. ;)
     
  4. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    Yes, my intention was the run the drill motor off the battery, as I've seen in several other places. Is there a way to bring the voltage down so I don't burn out the motor?

    I wish I could draw a wiring diagram, but I really don't know how.

    I don't intend to use the drill batteries, I want to run the drill motor off the power from the 12v battery.
     
  5. crutschow

    Expert

    Mar 14, 2008
    13,049
    3,244
    A wiring diagram is a simple representation of how you are going to connect the various parts. If you can't understand or generate one of those it's pretty hard to communicate. :rolleyes:
     
  6. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    You don't have to be a jerk about it. Every other post I read had helpful nice insight, not people being mean.
     
  7. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    This is the best I can do with a wiring diagram. I don't know the correct symbols.
     
  8. crutschow

    Expert

    Mar 14, 2008
    13,049
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    Sorry if I came across as a jerk or mean. That was certainly not my intention. :( I just meant that schematics are the language of electronics and it's very difficult to accurately convey an electronic design in words.
     
  9. crutschow

    Expert

    Mar 14, 2008
    13,049
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    That's fine. I now know exactly what you thinking.

    Below is one way to connect the limit switches with a single DPDT reversing relay.

    But you need some method to reduce the voltage to the drill motor or it will blow. For that we need to know the motor current with the anticipated load, so you will have to measure it with a multimeter. You might also consider a motor designed for 12V such as an automotive windshield wiper or door window motor from a junk yard.

    The other concern is that the reversing relay will require continuous power in one position unless a latching type relay is used. However a low power relay may work if it doesn't discharge the battery significantly for the time it's on.

    Motor Revers.gif
     
  10. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    I must have read your first post in the wrong tone. Gotta love the internet- no way to tell what someone means. Sorry about that.

    Where would I get said reversing relay? I haven't seen any like that.

    I've considered the 12v motors. I was hoping to use one I had on hand. There aren't any junk yards around that I know of. I know I can order them online though, because I had looked at that. But I suppose if the choices are buy more parts the make what I have work or buy a new motor, the cost probably comes out the same in the end.
    Thanks for your help. I appreciate it.
     
  11. crutschow

    Expert

    Mar 14, 2008
    13,049
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    The reversing relay is just a standard DPDT relay.
     
  12. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    Ok, so I found a cheap window motor and that is now on the way.
    Looking at your diagram, what does v1 mean? Is that a part I need? Also, u3?
    And I don't see the timer. Where does the timer go?
     
  13. crutschow

    Expert

    Mar 14, 2008
    13,049
    3,244
    V1 is your battery.

    U3 is the DPDT relay.

    The timer controls U3, which I didn't show. U3 is de-energized for the door up position and energized for the door down position (of course that can be reversed by reversing either the motor or the battery connection [polarity]).
     
    Last edited: Mar 28, 2013
  14. beccasev

    Thread Starter New Member

    Mar 22, 2013
    7
    0
    Awesome. Thanks for your help. Now I just wish all my parts were here so I can play with them! I'll let you know how it works out.
     
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