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Topic: Battery life indicator reflected in LCD display (Read 3787 times) previous topic - next topic


Hi all,

Firstly would like to say that I am using arduino for the first time for a project and am noob at it. So sorry if my questions are noob :smiley-red:

Ok, so I need a battery life indicator connected to my arduino which indicates a "Low Batt" warning sign to my LCD display when the voltage reaches low.

I need help as to how to come up with the low battery indicator circuit (no leds required as I'm gonna use the LCD display)..Just need a simple one which indicates when the battery voltage reaches a certain voltage and the warning will be shown on the LCD.

The arduino is battery powered (Using a 9V batt) and this is the battery that needs to be tested.

Hope you guys can help  :)


You can be sure somebody has done it before, and I don't think it's hard, but you first need to be more specific about the LCD.  This particularly applies if you have already got one.

There are two fundamental types

Character display

These are the ones you usually see on shields. They are referred to as 16x2 or 20x4 etc., being the number of characters and rows. I'm sure they can be used as a bar graph but it's probably not worth the effort.

Matrix display

These have a continuous cover of pixels rather than blocks of pixels to form characters.  They are designated like 320x240, just like your computer screen.  It is just as practical to to use them for text as graphs, even simultaneously.   

It probably won't help much at the moment. but here is a link for a clock for the Nokia 5110 LCD. It is 84x48. The sketch is a clock with a bar graph for the seconds that I hope to eventually adapt to read power.


and this might inspire you.....     http://www.youtube.com/watch?v=8vSWNTzZ9pA



Mine is a 16 by 2 LCD:

So any examples for this?


I can't recall but I bet somebody has done it - they usually have. I confess I was clouding this with my own intentions, a bar graph.
You may find just having a voltmeter saying "7v" in the corner of your 16x2 is entirely adequate, and there must be a gazillion of them.  This would simply mean that your real problem is measuring the voltage, and displaying it is trivial.

Even it is possible to use a 16x2 as a graphic indicator, and it may be possible to use a single character block for this. I don't think it is such a good idea, particularly in the face of better alternatives. It is likely to involve a lot of intellect in order to waste resources.


Here is a 16x2 displaying a pixel by pixel bar graph


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