3.3V step up regulator voltage monitoring

[fhenryco]

@flopp yes your link is to the method i'm currently using to monitor Vcc which is about 3.3V. But my battery is actually 2 AA in series which output voltage is 3.3 V only when new...and should decrease progressively. My question is: is it necessary to monitor the Voltage of this battery or is it safe to only monitor the Vcc which is the output of the step up 3.3V regulator ?

[flopp]

@fhenryco
If you measure after the step-up you will never know when it will "die".
You need to measure before step-up to see battery level

[fhenryco]

@flopp Ok but are you sure ? i mean if the step up fails to output 3.3V when battery level gets too low, monitoring a decrease of the regulator output (to arduino Vcc) might indicate death coming soon ... and after all this is all i need to know except if "coming soon" means " too soon" to react and prevent failure by changing battery

[flopp]

@fhenryco
If battery is below 0,8 step-up will not work and your Arduino will not work.
If battery is 2.3 you will get 3.3 output from step-up

[scalz]

stepup will simply fail, you'll get brownout, transmit problems etc..so you won't know anything in the end..
it's better to monitor your batt voltage. you don't need a voltage divider for this, as your batt voltage will always be <= vcc. So Analogread your batt voltage, and your range will be 0 to 3.3v.

[flopp]

@scalz is correct, use analog input to read batteries.
My link at top was to measure what voltage the Arduino I see getting. Sorry for leading you in wrong direction 😑

[fhenryco]

ok thank you

[fhenryco]

actually, as i now remember i was using the voltage divider to reduce the battery voltage below the reference internal voltage ~ 1.1V ... this is some people advice for better accuracy. I'm now wondering if i can avoid this (the voltage divider) and still have a correct precision

[mfalkvidd]

@fhenryco what precision do you need?

[fhenryco]

well i don't need great precision, just need to be alerted
when the battery voltage is getting dangerously low

[mfalkvidd]

@fhenryco then the method recommended by scalz and flopp will be great.