I’ve been fascinated with automatic chicken coop doors. My current auto coop door closer has been working like a champ for months. I received a lot of great replies to that thread, and one of them was from a visitor named Bob. I was so impressed with his design and pictures I asked him if I could post his comments and pictures as an article here. I’m SUPER glad he agreed. So, below are his words:
Here is the automatic door I built with an automatic car antenna (click the image to see it in action). I chose the antenna method because it has a built in stop when it reaches its end in both directions. This eliminates the need of more circuitry to control “run timeâ€.
Mine runs off a little 12v lawn tractor battery. The battery is kept up to charge with a “float†charger. The door opens and closes with a photo light sensor. The reason for the battery is so that a power failure will not cause a problem. The reason for the light sensor is so that the length of daylight does not need to be constantly adjusted on a timer. BUT, you can simplify things and use an ordinary appliance timer plugged into an AC outlet, and then use a 12v DC power supply to power the antenna.
This is just one way to use an automatic car antenna. With some imagination you could probably come up with many more designs.
As you can see the antenna is mounted upside down. The door is made from an 1\8″ ALUMINUM panel. It is light in weight but very strong. The door channels are 1/4″. I have a 3″ spacer connected to the tip of the antenna to the door. You can measure the distance you need to determine the spacing length. I used a piece of aluminum stock and tapped each side to mount it. The side on the antenna tip has a hole for the tip to set in, and then I used the tapped hole as a “set screw†to keep the tip in place. I have my tip connected towards the bottom of the door. This makes the length of the door channel a bit shorter in order to match the up and down stroke of the antenna.
Be sure to carefully measure the lengths and travel distances needed for the antenna to move up and down freely. I have heard of some discussion that the travel distance does not need to be exact because the antenna’s “auto stop†feature will sense the end travel and the motor will time out. But that will be up to you.
If you do not have some aluminum sheeting lying around, you can find some at Lowe’s or etc. Aluminum can be easily cut with your skill saw. Just make sure you have a carbide blade and wear safety goggles. Even some type of plastic sheet would work. Just keep it light and strong.
The door channels can be purchased also at Lowe’s or Home Depot.
The best price for the antenna was on-line at Beachaudio.com, but they may be out of stock. Just search the web for the least expensive “automatic antennaâ€. Mine was about $35.00. The antenna MUST only have three wires. (Beware of the non automatic antennas that require the user to “toggle†the antenna up and down manually). Two wires connect directly to your power source. The other wire that is not black or red, is the “up down†trigger. That is the wire that you connect to the timer or sensor circuit.
If you go with the 12V battery, the float charger can be bought at Harbor Freight Tools for under $10.00.
I have updated this article to mention that the there may be a better control system other than the night/daylight sensor that is described below. I have used this sensor for about a year. However, just recently I noticed that the control unit was sometimes “confused†in the mornings and would make the antenna move up and down erratically. Not fun for the chickens. It was mainly due to setting the photocell too sensitive in order to stay open at night as long as possible. Please be sure to read the later posts regarding an Intermatic ST01C timer. This timer is very unique because it does not rely on household current to operate. It is also very unique because it has an “astronomical†feature which updates the internal clock when dusk and dawn occurs in your region. It is powered by a 2 year lithium battery. Below is the night/daylight photocell circuit, if you decide to want to experiment with it.
Here is the circuit. Its pretty simple and self explanatory and would require someone that has done a little soldering in the past.
The only thing that is really not explained is the CDS photocell. One could try different types to see which works best. The one I ended up using was from a photocell variety package purchased from Radio Shack.
If you decide to go with the photocell circuit, the antenna’s power wires (red and black) must be always connected to the 12vdc power source and not be controlled by the photocell circuit.
A few thumbnails you can click on for the control box, door channel, battery / charger, photocell
On the other side of the box I have a little slider switch that makes the door close manually.
The tip spacer/connector will probably be the hardest part for a lot of people to figure out to. There plenty of ways to get that done. I had a piece of an aluminum rod that was solid. I drilled and tapped each side of it. There is a screw going through the outside of the door to one side of the rod. I drilled a hole in the rod for the antenna tip to sit in. The screw on that side of the rod is a set screw that keeps the tip in place.
(Rob Note: A huge thanks to Bob for this great design, pics and wrtieup and for letting me post it on the site. I know we are both looking forward to reading some of your comments!)
Bob, I don’t have a full multimeter, but I do have one that will do ac/dc volts and ohms. I did dig it out last night, but I’ve never used it before. I’m not sure what setting to put it on for the DC. It had numbers like 600, 200, and I’m thinking they were amps. Does that make sense?
So, would I clip the end plug of the converter, peel the wires and touch both tips of the voltmeter to each wire separately? How do I tell which is negative/positive?
Just to make sure I got this right: To test the antenna, once I know which wire on the adapter is which, I put the black antenna wire with the negative, the red with the positive, then touch the green to the positive. This should make the antenna extend. Then remove the green from the positive and it should make the antenna retract. If it doesn’t then what?
I’m going to print this and take it home with me. I don’t have internet at home to check while I’m working on it. Thanks.
I forgot to say that I might have a foot massager thingy that takes 12 volts, but I can’t remember what the converter was rated for when I was hunting for power supplies.
Yes, you got it! That’s the way the antenna works.
On your multi meter, look for the area on the dial that says DC. I have seen some that do not say AC or DC. They want you to put the connectors in the right holes. You can’t hurt anything unless you selectâ€Ohms”. Then you may damage the meter with the voltage depending on how it’s designed. So stay away from the setting that says “ohms†or has a “horseshoe” looking symbol or a “K” on it. That is for measuring resistance (ohms).
The black lead will always go to the common plug hole. Set you meter to anything above 12VDC. Then touch the wires to the converter. If you have a meter with a needle, it will move to the right if you have the correct polarity, otherwise it will peg to the left if it is backwards. If you have a digital meter, you will see a – sign on the reading telling you that you have it backwards. Switch them around and see what your meter does just for the heck of it.
After testing, I tie a knot in the positive wire so that I know which is which.
More dumb questions:
When I test the antenna, and I get it right, what I want to see is the antenna extend fully and the motor stop running? Then take the green wire off the power, and the antenna will fully retract? Is that right?
On Chris’s earlier description of how to hook up the switch, the black is the load, so I’m assuming that means positive. And the blue goes to the trigger wire. So, once I test my antenna, and assuming the wires are red (+), black (-), green (trigger), it will go like this:
The red antenna wire (+) to the black (load) on the switch, and the (+) of the power supply. The black antenna wire (-) to the (-) of the power supply. The green antenna wire to the blue on the switch.
Then I should be good to go as far as wiring?
Thanks Bob. I’m going off memory here, but the multimeter has a digital readout. And you have put one of the connectors in the right hole to read ohms or volts. The middle connector (i think it was the black one) stays put. If you want to read ohms you put the red connector on the left hole, if you want to read volts you put it on the right hole. And it was a dial in the front. The left side of the dial is for ohms, and on the right side it has maybe 8 different settings. The first three or four are in red and go with the V~, which I figured out means AC. The rest are black with a V with a line and dotted line under that, which I deduced means DC. But the setting options aren’t volts. I think it said Amps, but I can’t remember off the top of my head now and it had numbers like 600. I was hesitant to use it cause I don’t know which one to pick.
So, I put one wire on each connector? If I have the correct polarity it will mean what? That the wire on the red connector is the + and the one on the black connector is the – ? If not, then it is the reverse.
Maybe I should read up on how to use a tester. I am embarrassed to no end because I did take an intro electrical engineering course in college and got and A to boot, but must not have really learned anything practical.
I was planning on using labels on the wires to keep them straight! I would probably forget what the knot meant. Thanks.
the red antenna wire is a constant hot it is always hooked up to the postive of the power source. the black antenna wire is a constant ground and is always hooked up. the green wire is s votltage senser wire when current is applyed the antenna extends when the current is removed from that wire the antenna retracts. so when you are hooking up the timer switch the switch simply acts as a voltage on off for the green wire……..look at the pics I uploaded, because the pic shows what wires are used and what ones are cut off or not used.. i cut mine off…
You are correct about how the antenna works. As long as the green wire is connected to positve, the antenna will stay out after its duration. Green wire off, antenna retracts. But remember to always keep the black and red wires connected to 12VDC constantly. Which is what will happen anyway after you wire it all up to Chris’s timer.
I don’t want to step on Chris’s toes but I will help, just in case he does not answer you in time. Per Chris’s post #61 you are correct with the wiring.
Knot means hot simple to remember …..
No toes here Bob , lol, we were posting back to back …
and that is ok too I was out and about when one of these came in …it is about the answers , not who answers ….. thanks
Vadgo, You are doing great. You seem to understand your meter better than you think. Just plug the meter leads in just like you thought. Red into the DC hole which is the line and a dot. Then the black into the “com” hole. By doing this, you cannot hurt anything no matter where you turn the dial.
Just hookup the leads to the converter and turn the dial until you get a reading close to 12V. You may see a little more, thats OK. Now pay attention to see if you see a – sign on the display. If you do, resverse the wires and it will go away.
Excellent. I think I have enough info to be dangerous. I’ll try it out tonight. Thanks for the great help.
Chris, I can never get the pictures of your setup to open up. It always times out on me. Only one time it worked, but after the first picture it kept timing out.
I’m sure this is pretty dumb, but was I right when I said that if the polarity reading is right on the adapter, that means that the wire connected to the red voltmeter connector will be the + and the one on the black will be the negative? Thanks.
Bob, actually the hole for the red connector only says volts. It’s on the dial that the firs three or four settings are AC and the rest are DC. I’m glad that voltmeter is idiot proof.
Yes,
you are correct about the colors and polarity.
Thanks Bob and Chris for your patience and all of the help! I got the antenna to work!
Chris,
I hooked up the switch set an On time and an Off time to test it, but I don’t think I’m doing it right. After setting the program, i chose AUTO. At the “ON” time nothing happened, then at the “OFF” time nothing happened either. I had to hit “on/off” to turn the light bulb white, and the antenna extended, then hit it again, the light bulb goes black and the antenna to retracted. I’m not sure why the program didn’t work. I’ll try again tonight to see where I goofed. If you think of anything I need to do, let me know.
Since at “On” the antenna extends and at “Off” the antenna retracts, that would mean I have to set a program with the “ON” to “Dusk” (close door) and “Off” to “Dawn” (open door) so the door operates right. Right?
Another question I have is do I want to set the timer “Dawn/Dusk” times to my local dawn and dusk times or to my local sunrise and sunset times? Or some time after sunset/sunrise?
I just looked up my local sunrise/sunset. It is 7:41/18:15. Dawn/Dusk is 7:13/18:43. So I think I would want to set Dawn to be at least at sunrise. Or would that still be too early and predators could still lurk around? My dusk time right now is half hour after sunset. Would that be appropriate? I think my chooks are in their coop by that time. I’ll have to observe them to double check. Don’t want to leave anyone out!
What size of wire do I want to buy if I want to mount the switch farther than the antenna wires will reach? Same size will work for the power supply, or different size? Thanks.
With regards to the wire size I would use a 18 ga stranded wire or a wire equal to the size on the antenna.
As far as the programing goes I had to phone them to achieve that as stated in my post about the timer unit. Keep this in mind the map that they use to determine Zones is based off the North America map, not sure were you are, but keep that in mind. Be sure to tell then were you live.
Also you can advance or delay the opening by about a 45 min window with regards to the sunset auto mode, they can advise you how to do that, I would, check to see what time my birds were all in on a regular basis, and, while the door is new to them , make sure they do not stop and sit in the door , as there is not safety stop for this door. the light on indictes power to the antenna and that would or should cause it to close. The light off , would indicate the door would open up as power would be shut off. As far as the opening time goes..
I leave mine in until it is a hour after sunrise and the area is well lit , you could go even 2 hours, remember, that some nocturnal animals do not go back to den right away upon the sun coming up, skunks are 1 of those , Fox are another.
I just leave those to the Infrared (IR) heat seeking shot gun setup I have…lol , but thats another story …….. If you go to the web site for the timer you can find the customer service number for your area to use , or look in the instructions , it is there as well..
hope that helps ….
Oh 1 last thing, I was asked by email , why i elected to use a nylon cutting board rather than a metal door.
Well I thought about it at the time and had decided that metal bends, metal is very cold and can condense water on it and the tracks and freeze, a nylon door has a natural slide skid to it, and even if the tracks condensed , the water will not stick to the nylon, and thus eliminated the possibility that issue could come up. The Nylon door was also pre made and, if you buy 2 sets of the cutting boards, you have a replacement door to use if needed.
It was just a personal choice.. both work well…
IR heat seeking shot gun setup. Wow. I better not show up at your place at night to take a look at your chooks!
Thanks for the insight of the door. I have a galvanized steel piece that I was going to use, but it does get below zero here, and I’d hate to have to fight to thaw a door in that weather! Off to look for a nylon cutting board! Thanks for all your help.
Not too heavy! Unless you will install a counter weight. Fortunately we don’t have freezing issues hear in So Cal, zone 19. I use a light aluminum pannel sheet. But strong enough so that you cannot put your fist through it.
I thought the counterweight idea was good and was planning on adding it to the setup. If it turns out too heavy, I wonder if I could use cabinet drawer slides with ball bearings and mount the door sideways? Would that be easier on the motor as well? Tracks would probably gum up with all the dust. Do the vertical tracks fill up with dust? Those of you who’ve had the setup for a while, have you noticed any dust build-up on your antenna that might lead to early damage of it? I was toying with the idea of mounting a clear tupperware tub over the antenna with just a hole for the antenna to operate to minimize dust buildup.
My old barn is very dusty.
dust should not be a worry, the metal door and a dirty track could be a issue, but remember nylon slides or skids are common. the less parts you have that have to be cleaned and move the better. If it becomes a issue hose the track off once a year, but i do not really see how that would be a issue with a nylon door.
and the wieght of the cutting board i used was less than 1 lb…I have grabbed the door as it was retracting and it pulls out of my hands and is almost impossible to stop, I do not know if my antenna is the exception to the rule, but it appears to have a very strong motor.
as far as the antenna being covered, these are made to be used in a car sometimes inside a fender area were dust and dirt can still get, I would not be the slightest concerned about that .The metal antenna itself is self cleaning by construction. As it retracts it wipes the dirt off .
Well, now, I may frustrate you all since probably these questions have already been answered. I got my antenna today- three wires, but there is also a heavier plug-type wire on the shaft thing that the antenna entends from. Does that just get removed? I would like to hook this up to a regular timer and use an extension cord for power. Help me. Could someone speak slowly and clearly in laymen’s terms so a girl could understand what parts I need and how to hook them up? Thank you.
Can anyone please help? I read all the previous entries, but it’s unclear to me how to wire this antenna in such a way that I can use an extension cord and a regular lamp timer.
Hi Mary,
Sorry if I may sound a bit direct but unfortunately this project requires some electrical “handyman” knowlege. The antenna requires 12VDC. You cannot simply connect a house timer that plugs into your wall to the antenna. If it were that simple, there probably would not be over 100 technical posts here.
Here is a quote from post #17 that may pertain to your situation. The links are examples of converters that will work. However they may not still be available from that supplier. If and only if you have the fully automatic 3 wire antenna, you can do the following with 1 house timmer and 2 power converters.
“Use this type for the antenna’s “trigger†plugged into the 120V timer. Meaning that it takes little current (amps) for the trigger.
http://www.allelectronics.com/make-a-store/item/DCTX-120/12VDC-200-MA-WALL-TRANSFORMER/-/1.html
Use this type constantly connected to the antenna’s positive and negative leads. Meaning that you need at least 3 amps for the antenna’s motor.
http://www.allelectronics.com/make-a-store/item/PS-1263/12VDC-3.5A-SWITCHING-POWER-SUPPLY-BLEMS/1.html
If you choose this method, make sure you get your polarity (+ and -)correct. Simply tie both sides of the transformers negative wires together”
So, am I right to assume I need two 14v DC power packs. One I will connect the red and black wire from the antenna to and the other I will connect the green wire. Did I read that I have to connect the ground from both power packs? If I cut the little plug thing from the power packs will I be able to tell which is the ground? The power pack with the green, or trigger wire, will go into a lamp timer? Right?
Oops, I sent that last post before getting yours, Bob. I did read that in #17 and didn’t mean that I could directly go to a timer. I did realize that I needed the power pack things. You’re cutting off the plugs on the power sources, right?
Yes,
You are correct. The two negitive leads of the power packs need to be connected together to create a “common ground”. That is also where you will tie the black antenna wire to. After you cut off the connectors and strip the wires you will need to know which wires are positive and negitive. You may want to borrow or buy a cheap multimeter. You can find them between $5-$10.
And yes, the power pack that has the green (trigger wire) attached will go to the timer.
Thank you, Bob. That’s exactly the information I needed. I have a multimeter, despite sounding inept in my previous posts. I’m guessing I could just use shrink tube where the wires connect. Now I just have to find the power packs.
I noticed that the power pack referenced for the positive feed is a “switching” power supply. Is that necessary or can I find any power pack that is at least 12vdc and at least 3 amps? I’m not sure what the “switching” is.
Thank you.
Hi Mary,
Good question.
Both types that you mention are fine. Usually a new “switching” power supply is less expensive than a traditional type because they are less expensive to manufacture. But use whatever you can find at the best price.
FYI,
A switching supply does not use a transformer to reduce the voltage down. They are using other solid state devices such as “switching transistors” to step the voltage down. This makes the unit less expensive to make and alot lighter than one with a transformer. There are pros and cons to this, but for the antenna, they both would work fine.
Bob Thanks a lot for all the info on the coop door the chickens are happy and it has made my life a lot easier. I used the auto antenna with the dark activated switch,12v lawn battery,and a solar panel. and the door has worked flawlessly for six months.
Hi Mike,
That’s great!
Which dark activated switch did you go with?
I went with the one you suggested in post 11.
Great. Then I know it works. Thanks for giving me and the others an update on your door.
BTW,
The only problem I had on mine, was that I had a pre-mature dead battery on my system. I found out that the battery was not getting charged. This was because of the battery clamps on the trickle charger. They were no longer making a good connection on the battery posts. I guess the metal or coating on the clips oxidize quickly or maybe my posts were the issue…Anyway, I cut the clamps off and fasted the leads directly to the posts along with the circuit wires.
Here is a link to a schematic may be help-full.
http://futurekit.com/basic_elec/FK403E-2.pdf
Yay! I’ve got my antenna door opener all set up and working. The electrical wiring was the easy part. The hard part was getting the unit set up in the coop with the chickens jumping around trying to get a good look at just what was going on. Thanks again for a great design and for all the help.
This is some wonderful work! Very impressive!
Were have I been?
I have been thinking of a door lock system for any type of pet.
With Reed switches to allow only critters with the right collar or leg band would be able to enter. This may be handy for free range chickens to enter a run type structure before the Coop door.
I started reading this tread a couple of weeks ago, and the next day all of the comments before Oct. 26 disappeared! Are they reachable somewhere else? I can’t find many details, such as the brand of timer that will automatically adjust for dawn and dusk. Thanks.
Matt, you’ll see a link right at the bottom of all the comments that says “Older Commnents” Click it and you’ll have access to all of them. Here’s a direct link: http://www.nifty-stuff.com/auto-coop-door-ii-antenna.php/comment-page-2#comments
Could you show detail of wiring up the pins of the relay, what did you use to protect LDR from the weather I assume it was placed outside the chicken shed to get maximum light Thanks JohnP
Hi John,
First I would like to say that I would spend the $30.00 and go with Chris’s design. It does not use a photocell and will work with 12V. Please check out the post from September 17, 2009 at 2:20 pm You can find the post from the “older comments” page.
The unit can be bought online from 1000bulbs.com
Now back to the kit if you decide to continue.
If you have the relay, it should show the same type of diagram. The relay’s voltage is applied in the same place where the D1 (diode’s) leads are. Then the right side show part of the relay’s contacts. You will only be using four of the relay’s contacts. Two are for the coils voltage, and the other 2 are the pole and the N.O.(normally open) pin.
The CDS photocell is mounted (hanging) under the coop’s roof eve. It is protected from the rain.
Excellent design! I wish someone would come up with a way to cut power to the sensor wire on the antenna and the power to the relay after the coop door opens until time for it to close again. I am going totally solar and I am afraid the drain on the solenoid and antenna sensor will create an unnecessary power consumer.
Hi,
I was the one that came up with the intermatic switch idea ……….
there is no drain to the deep cycle battery I use…… I have been totally solar at the coop for 4 months now , no drain….. no pain……
the only thing that happened was the controller switch reset from auto to manual , and had to be reset, it was caused by motor wave interference , and upon calling the intermatic Co. they sent me a noise suppressor at NO charge…….
They also told me that the internal replaceable switch battery typically lasts 2 to 4 years……
Yes, the only current draw when the motor is NOT running is as follows;
Daytime, the circuit that is monitoring the photocell. It is so little that I’m not sure that it can even be traced on a milliamp meter.
At night there would be the most because the relay is activated. But once again, the coil specs on the relay are so little.
The antenna’s trigger wire does not pull current. it only senses if there is voltage present or not.
So you should be perfectly fine.
If you go with Chris design from post September 17, 2009 at 2:20 pm, that timer unit only needs a small battery replacement every couple of years! That would be the best way to go. Basically the only time you would have current draw would be when the motor runs!
Good luck,
Bob
Hey Chris,
I’m actually going to go with your idea. Sometimes when it get dark outside earlier from clouds, I get a little wottied about the door closing a bit too soon. And if I set my photocell control to be more sensitive, it confuses the circuit and the trigger goes on and off for a few minuets, causing the door the jump up and down. I want a delay to happen. And the best way I think is to go with your timer idea. That way I can set it for an hour after sunset. I believe that is what you are doing?
Can you please explain what happened with the “motor wave interference”? I don’t see how this would happen because the motor would not be connected to the timer, only the trigger wire is.
Bob
yes i can clear a little of that up ,
the motor on the antenna seems to create a interference that caused the timer to reset from auto to manual,
it did not erase the settings it just made it go from auto to manual in the switch , the item they send you free of charge stops that “RF” motor generated interference ,
the switch has the “moon ” phase or sunlight adjustment for the seasons in it, it will shut the door at the same time , like a hour after sunset through out the year and you never have to adjust it for the light differences from summer to winter .
I have to say also that it did not have any issue for 3 months, and then it reset once.
I would say you could most likely never even have the issue, or, you could buy the switch, call the company up and ask them yo send you the RF choke free of charge …that way if you do need it you will have it.
The only thing you would need to tell them is that the timer keeps getting reset to manual, and the cause of that is Motor RF interference according to them ….. just a idea in case….
Cool, thanks Chris.
I have some RFI suppressors (chokes) in my parts bin. I’m a Ham radio operator and sometimes RFI will get into things.
Thanks for the heads up,
Bob
Hey folks (especially Chris and Bob),
The antenna idea is perfect – brilliant! – full marks for appropriate engineering to whoever came up with that idea. I liked the idea of the electric window closer too since they often have the safety stop trigger which might save a tardy chicken from being squashed by the descending door.
But I think I’ve solved that problem a different way and I’d like to share my own minor improvement to this team effort. Instead of attaching the antenna tip to something bolted to the sliding door, I used some wire (about 1.5mm diameter). I drilled two holes in the top of my door about 15cm apart, tapped a 3mm thread into the tip of the antenna and put a short 3mm bolt into it (with a washer), leaving about 1cm of thread exposed. I then twisted the wire tightly around the exposed thread on the bolt and took the ends down to the two holes in top of the sliding door. Now the door lifts under the force of the antenna motor, but descends under the force of gravity – plus a bit of pushing because the wire is fairly stiff. But if I put my hand under the door as it tries to close the last 10cm (chicken injury zone) the wire simply bends and the antenna continues pushing through to its normal stop point. The amount of downwards pressure seems light enough to give the chicken a push, but not enough to trap or squash it.
I look forward to getting my hands on an Intermatic ST01C soon and a small solar panel to charge the battery too, but for now it’s running fine with a 350mA 12V smart charger on a 7Ah 12V lead acid battery to power the antenna motor, and a 150mA 9V DC plug pack (puts out just under 10V open circuit, so you don’t need a 12V source to trigger the antenna) I had lying around on a mains timer as the trigger – all stuff I already had. In fact, the only piece I had to buy for this (so far) was the antenna and that was $15 from an auto wrecker. And it’s working great 🙂
Thanks again everybody!
Hey Leon, Great idea. But now you do not have an excuse to make periodic fresh chicken soup 🙂
Good on the Intermatic ST01C timer. I installed mine a couple of days ago and so far I love it. I set the timer to think that dusk is 30 min later so that it is 100% dark outside before the door closes.
Thanks again Chris for finding this timer. I hope all the folks read down to these posts before going with the photo cell idea that I had. It does work, but I see no need for it now that there is a self adjusting astronomical timer available that does not require household current to run. We just need to make a habit and change out the lithium battery before it dies. Maybe every year to be safe. If I get real bored someday, I will put together a little 3v regulator chip that can run the timer from the 12 volt battery. That way no lithium battery in the timer would be needed.
Bob