Tuesday, June 11, 2013

Solar Powered Self-Propelled Turkey / Hen Coops are operational!

Yesterday we hit a milestone!  Finally, after months of delay, we re-activated the fist of our solar powered self -propelled turkey / hen coops. If you recall form a previous post, the last design worked ok except we struggled with the anchor point (ground would be too hard in the summer)  and the constant extreme tension was pulling the winches and lumbar apart.  This latest design solves both problems!

fist, we created the coop anchor. This is a 1000 lb block of concrete encased in old tires (recycling!)  with rebar hooks for moving and attaching the coop winches to.  At 1000 lbs, the anchor is heavy enough to outweight the coops themselves so we no longer have to drive a series of stakes in the hard ground.  We simply use the tractor to pick up the anchor by hooking the tractor forks through the top rebar loop, move it, and set it down.  The coop winch cable connects to the anchor easily, and  presto,  a self-propelled coop. The anchors cost about $50 in concrete and rebar... the tires are of course free.

The winch anchor in place. notice the cable form the lower front  loop. 

here is a shot of the extended cable. this is the stock cable, about 75 feet long. We can add a 150ft cable  to allow for less labor. 

The second problem,  constant tension, took more thought.  The winches are auto-braking type, meaning once the run to a point they brake there and hold tension indefinitely. most cheap winches do this. The only way to remove tension is the revers the winch slightly after running it to pull the coop. But how to do this without adding yet another timer?

Where there is a will, and some creativity, there is a way! I ran across an unorthodox idea.... using a large capacitor  as an inline timer circuit. I say unorthodox because technically, this use is bad for the capacitor and cuts its life. We'll see how much that is.  I dont think it will be significant.

I built a simple inline RC circuit to reverse the winch any time it was operated, just enough to release tension.  The inch itself has a relay drive. you connect 12v to one relay and it moves forward, the other and it moves backward.  My timer output is a relay contact also, with both positions (NO and NC). TO make this work, we connect the common of the timer relay to 12V, the NO contact to the forward winch relay, and the NC contact to the inline timer circuit, The timer circuit is just a capacitor (about 4000mfd) in parallel with 500 ohm resistor.  This goes inline with the winch control wire for reverse.

How does this work?

When the hourly timer triggers calling for a coop move on schedule,  this triggers the winch timer. The winch timer energizes its internal timer relay giving 12V to the winch control relay. The winch moves forward pulling the coop. the timer goes for about 5 to 10 seconds and moves the coop 1 to 3 feet.

In the reverse timer circuit ( the capacitor and resistor), there is now no voltage applied to the circuit since it was connected to the NC contacts of the timer relay. Therefore, any charge within the capacitor bleeds off through the resistor.

When the timer stops, the timer relay de-energizes. This removes 12V from the forward winch relay and the coop stops moving.  At the same time, the NC contacts of the timer relay close again, providing 12V to the top of the reverse timer circuit. Since the capacitor is discharged, it immediately charges to 12V. This energizes the reverse winch relay for about 3 seconds. Once the capacitor is charged, the current stops flowing and the reverse winch relay stops.

So, as long as the winch runs for long enough to discharge the capacitor, the end result is forward movement followed by a removal of all tension from the winch cable.  This repeats each time the schedule timer runs. (a further improvement would be to adjust the resistor size so that the trickle current in between winch run times is minimized to save power. )

So there you have it... a solar powered, self propelled turkey / hen coop  that can house up to 100 chickens, complete with nesting box, or 50 turkeys. They live on real ground, have safety from predators, self contained water and feeder, roll away nesting box for clean eggs, and get fresh green grass hourly. All we do is fill the water, feed, and collect eggs, then every 3 to 4 days move the winch anchor with the tractor.

here is the winch, ready for action. the small box on the left is the winch relay box. 

The electronics hiding under the solar panel. Before rain comes I'll need to enclose this is some sort of plastic box.  you can see the battery, the solar charger, with two timers mounted on top. Wires could use some tidying up. 

here is a shot of the electronics. The schedule timer, with up to 20 set times per day to activate. Above that is the winch run timer. the white circle control sets how long the winch runs per activation and thereby how far the coop moves. at the top right is the reverse timer circuit. I used 2 capacitors because we didn't have one single large enough. 

the electronics and solar panel ride alongside the coop on a pallet mounted on skids. the pallet is  hooked to the coop by a small chain and hook. before wind hits, i'll need to mount he solar panel to the pallet more securely. 

So there it is, almost perfect! Just a few finishing touches and.. well.. build 6 more !

1 comment:

  1. First little problem showed up, not with design but my own hurried approach. There is a little plastic control box near the winch that houses the direction relays. I left that sitting behind the winch, not screwed tight. Sure enough, the chickens started pecking at the box through the fencing and knocked it forward onto the ground. Next time the coop moved, it ran over the box, pulling the power leads completely out.

    easy enough to fix, just an irritation really. missed a half a day of movement due to this. a half a day of movement cost us a few dollars in extra feed.

    What else can these birds break???