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[on:]

Does anyone know how to make Arduino aware of its battery level? For example, before the Arduino dies completely, I'd like to have it blink a LED to alert the user that the battery is dangerously low on charge. Maybe by somehow regulating the voltage and passing it to an analog input? Thanks for any help.

[Reply #1 on:]

Well you can take your battery, step the voltage down so that 0-5v is scaled to the battery and feed that into one of the arduino's analog input pins.

You can use a handful of parts, zener, resistor, transistor to switch a digital pin high or low based on what an external voltage is but I've not done it yet.

Something like this but the transistor collector would be connected to a digital pin that's being pulled high by a 10k resistor to +5v. The rest I'd have to sit down and figure out how to drive the transistor as I don't think what is there will work right.
http://www.reconnsworld.com/power_12vbattmon.html

[Reply #2 on:]

Did you have a look at http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1199738420 ?

Nicolas