Very low power with alkaline battery
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I'm building my own pcb for mysensors and i'm doing a lot of tests since 1 year now.
My parts are all selected to work between 1.9 and 3.3V :
- Atmega328p (100na interrupt powerdown, 4.3uA watchdog powerdown)
- rfm69 (100na powerdown)
- SI7021 (powered by pin)
- OPT3001 (powered by pin)
To power my pcb i have done two tests :
Directly powered by 2xAAA battery where i get ~4.3uA of current when sleeping (due to 328p watchdog)
Then i checked about alkaline discharge rate... that's < 0.3%/month (wikipedia) I take an optimistic value of 0.15%
For a 1200mAh AAA battery that's : (0.15/100)1200 / (3024) = 0.0025mAh per battery.
For the first test it's 2.5uA self-discharge for <1uA consumption
For the second test that's 5uA self-discharge for 4.3uA consumption
Now i'm asking myself if it's worth trying to go under battery self-discharge rate for sleeping node ?
If you go around 6 or 7 uA you are still going for a long battery life (depending how often you are sending data)