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How can I make a countdown timer that runs for 3 years? Answered

I want to have a countdown runner that counts down the seconds (94,608,000). Ideally it only displays the seconds and has no other function. Ideally it does not have to be connected to an external power source but connected with some kind of battery that does not have to be exchanged for 3 years. 

Any ideas how to do this? Arduino? 
Very new to this community and grateful for any advice!


What do you intend to display the count on ?

I think you could do this with a very low power processor and two 8 digit LCD displays. The Arduino is probably good enough, but you will need to be able to do some cute programming to keep the processor is sleep or standby for 99.999999% of its life.

There is a very good code example called, IIRC, Nightingale, where the processor does just that.

For now I was planning on a LCD 16x2 I2C. But I am open to new suggestions!

Couldn't find the code - do you have it handy or should I try again?

That kind of display takes too much power for what you are trying to do. I'm thinking of a display like eInk

Try this link


Minimum power occurs at minimum voltage and minimum clock frequency. If all you need is an update once a second, you don't need any computing power, and a simple 32768 Hz crystal to drive the processor, making it its own RTC

That sounds very promising! Any chance you have time to go into detail about how exactly I would do that?

Its pretty complex. I'm not sure how you'd handle it in the Arduino eco-system. This article is very informative.


For a display, I was thinking of this:


This display draws 10mA ONLY during the update of the data on it, which you could do in a millisecond or so, so the average consumption is roughly 300uWh

If you can afford to update once a minute, instead of once per second, you will reduce the power consumption by a factor of 60, essentially, so 5uWh.

I am pretty sure, one 3.7V Lithium battery will suffice.


11 months ago

Simple Citizen watch has hung on my wrist over 12 years using only ambient light for power from the photovoltaic face...

You could buy a watch.. Regrettably it does not record years or months, but it may not be the only model..

Don't use a Ni-mh battery.

How about a big battery and a big super capacitor, so it won't reset once you have to replace the battery?

Thanks for the input! Doing my research now on how that could work.


11 months ago

A Chinese black blob uP commercial product dependent on CR lithium could not even do a full 2 years.. Opened and replaced the CR2032 battery just for you..

Click the pic to see a whole image..

Bad countdown.jpgBad countdown2.jpgCR2032.jpegBad countdown3.jpg

Thank you!! What is the "countdown to" product that you have on the pictures? Any chance it can be connected to a more powerful battery? Or combine with a super capacitor (see comment above)?

yes that also was my first google search :)
skill set is minimal. basic coding skills. that's why I was hoping to get some inputs from the community?


Harder than you think.

For accuracy your going to need a real time clock and a micro processor to read it and display the result.

This will require programming - are your skills up to that - If not start with something simple and work up or copy someone else.

You can do it on your PC


I did this over 2 years when counting to my retirement. The display is on th desktop all the time the PC is on and uses the system clock to calculate.

I'd really want it to be physical (I want to give it as a present to a colleague). Do you have any advice or similar projects I can use as references to make it happen?