One question is why this specific voltage? What gives this voltage? If 2 rechargeable AAs or AAAs, why not just non-rechargeable ones? The circuit linked to above monitored one input--monitoring a second would not make much difference. How often do you need to check the ADC reading? One of the tricks the linked circuit used to minimize battery drain was to poke the ADCON0 register to turn off the ADC module after any use, which might or might not make a difference depending on how frequently ADC is read.I am looking at around 2.2-2.4v
The 08M2 chip claims to be programmable across its entire operating voltage range, however, at low voltages, serial communications may become unreliable, which may be the problem.FWIW, I had weird issues programming an 08M2 operating on a 2.5V supply. Even the hard reset method didn't work. I wanna say it might have been due to insufficient current from the vreg. I have a thread on that here somewhere.
Make sure to include a pulldown resistor on the serin pin in your final circuitI don't want to include the download circuit, so will be programmed out of final circuit and then swap into the final thing so that soulmate be an issue.
That is good info to have for future reference, thanks