low battery circuit

on my pic I am running 8v to the 5v regulator and then feeding it to a 3v reg regulator powering another circuit. pic runs off the 5v reg

could I use the 3V reg as a balance to trigger when the 5v reg goes down to 4v, using analog readers, since analog input value would be a ratio of 3v : 5v (charged) but would change the ratio when the 5v voltage dropped to 4v,,


could I do this, is it possible, would it work!!!?

Does the pic have an A/D converter?

yup, analog readers, ! , but is my theory correct?, could i simplify out the 3v reg by chance?

could I use the 3V reg as a balance to trigger when the 5v reg goes down to 4v,

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Why would your 5 volt reg go down to 4 volts? unless its bad. Is this for a failsafe? Andy

ya for dying batteries on RC...

using analog readers

You are confusing us with such talk. Thinking you mean the PIC ADC input ?

Just use a voltage divider to cut the battery voltage in half and feed it into the ADC input.

Use the internal voltage refs.
When the battery is 8V the ADC will read (1023)((8/2)/5) = 818.
When the battery is 4V the ADC will read (1023)((4/2)/5) = 409.