Battery Lifespan

This may be a retrograde suggestion, but the most efficient way to display seconds would be to use a quartz mechanism with the stepper motor wires brought out rather than driven by the internal oscillator and divider. These little stepper motors only need a minuscule current at around a volt for a short period to drive them on, so consume almost no energy or current. Then the seconds display is just a conventional hand. You could even use the rest of the train to drive the minute and hour hands.....

True, but it would not be the design that I hope to create.

I tested the current draw again today with an AVO with a large, clear dial. It showed 45ma, rising to 55ma when an LED flashed.

James.

An update on battery life.

For what it is worth, using four alkaline 1.5v C cells to power the Uno, a LCD clock display and LEDs flashing each second, minute and hour, along with a flashing LED for quarterly and hourly chimes, the system became unstable after seven days. The chime LEDs are disabled automatically at night.

Whilst I know that this could be improved by following the suggestions given here, I think that I have concluded that I shall need to use a transformer for the final device, reserving a battery for back-up, should the mains go off.

Thank you for your advice.

James.

Thank you for trying the experiment and letting us know the result.

As the low-power members of the Arduino family consume about half as much power as Uno, you would still only get a fortnight out of four C cells - the answer is still a transformer.

Looking more deeply into earlier suggestions of putting the Arduino into sleep mode, I don't think that's a good idea in your project as it stands. In sleep mode pretty much everything is turned off including the Arduino's clock oscillator. The low-power timer used to wake the Arduino up periodically is an RC oscillator - not accurate. The solution is not to use the Arduino itself as the timekeeper, but to connect it to a Real Time Clock module like this, as described here. Then, you can put the Arduino in power saving mode waking up periodically to check the time, and only updating the display and striking as needed before dozing off again. RTC chips are ultra-low power devices, typically lasting 2 years on a button cell.

If I were you, I'd build the clock as originally conceived and may be return to these more advanced possibilities later if it suits you. One of the nice things about microcontrollers is that you can come back and improve the way they work (accuracy and power-saving) without having to mess with a clock or model's mechanicals.

Dave

It's worth looking at this excellent tutorial on redcuing arduino power consumption on the Sparkfun website.

I've had an RTC module running on a 2032 lithium button cell for nearly 2 years and going strong, so taht's agood idea of Daves.

Neil

Dave,

I have also come to the conclusion that I am better off with a transformer and worrying about saving power at a later stage. I should have to reduce consumption dramatically to make much practical improvement, especially once the solenoids are in the circuit instead of LEDs.

I am already using an RTC to keep the time, the RTC module having its own battery. The Uno interrogates the RTC for timings, with the Uno controlling the functions at intervals determined by the RTC.

Neil,

I shall have a look at the Sparkfun article. I have used a few ideas from that site, but not on this aspect.

The circuit that I have built uses a LED display to show the time, with a couple of press buttons wired in to advance and retard the time. This will be used to set up the time whenever required, rather than plugging the final clock into a laptop and setting the time via the IDE. I shall arrange for the display to switch off when not required. Ultimately, I should like the finished device not to require a computer to be viable.

Again: thank you all for the help and suggestions.

Regards,

James.

Edited By James Alford on 13/04/2018 07:15:38