63Views2Replies

Author Options:

How can I power up an LCD display with a lemon battery to show a message? Answered

I've seen lemon clocks and would like to do something similar but I want the LCD to show an 8 character message as soon as it's powered up.

I know how to use an LCD with Arduino but Arduino won't work on such low voltages.

Any help would be greatly appreciated.

Discussions

0
Josehf Murchison
Josehf Murchison

18 days ago

Arduino UNO or Arduino Nano More lemons in parallel about 500 to 1,000, larger zink/ copper electrodes, and a buck booster. It may not be practical, but it will work.

0
Orngrimm
Orngrimm

18 days ago

Google "Energy harvesting".

Basically, your lemonbattery will need to provide power over quite a long time until the seconday battery is sufficiently powered to run a arduino for a very short time. See https://forum.arduino.cc/index.php?topic=418299.0 for a few insights on how much power an arduino pulls and how to lower that a bit...
But an arduino is horribly inefficient in terms of "Brainpower per joule of energy used". Thats the tradeoff you need to make for convinience with the IDE and all the ready-to-go-libraries.

If you want to go low power for continuous run, you will need to go in the realm of sub-Milliwatt. Arduino is in the ballpark of 36mW. So... Like factor of 40 too much power needed...
See, a lemon-battery normally generates about 0.9V @ 1mA max... Thats below 1 mW.
A STM32L01F4 as an example can run from 1.7-3.6V @
– 0.54 μA Stop mode + RTC + 2-Kbyte RAM
retention
– Down to 76 μA/MHz in Run mode
See https://www.st.com/content/st_com/en/products/micr...
Lets say 76uA/MHz @ 3.6V --> 274uW/MHz.
This gives you a speed of about 1.8MHz for 0.5mW. I go with 0.5mW consumption as i will have loss in DC/DC-Conversion.

With 1.8MHz clock, your Microprocessor will not be the fastest kid on the block...
But if you dont run continuosly, but intermitten (Like every second for 1ms to update the
LCD) if your LCD features a "hold" function, this is very likely to be possible. With 1/1000 runtime, you can go with the fuill speed of 32MHz and still have a lot of energy to spare. With a lot i mean in the microjoules...

Anyway: The Consumption seems doable.
Now you need to boost your Lemon to a proper voltage.
Either connect multiple lemons in series (X times 0.9V) and have a simpler life) or you stepup the voltage.
Possible candidates are after a VERY quick search stuff like SPV1050 from ST (https://www.st.com/en/power-management/spv1050.htm...) or a few of the TI ones at http://www.ti.com/lit/sg/slyt593b/slyt593b.pdf

So basically you have 2 options:
[Lemon]-[Lemon]-[Lemon]-[Lemon]-[Lemon]----[uProcessor]-----[LCD]
or
[Lemon]----[DC/DC]----[uProcessor]-----[LCD]