Couldn’t wait for the breakout boards… Test platform for sleeping, no vreg, 2x AAA alkaline batts.
5 hrs in, ESP.vBat reading 2.740 at -3C. Initial reading from fresh batteries was 3.330. Sleep time was 60 seconds, increased to 300 seconds.
15 hrs in, ESP.vBat reading 2.711 at -2c … the 5 min sleep seems to have helped.
Roughly 27 hours now, vBat at 2.63, temp -2.5C… alkaline at cold weather don’t mix, not that -2 is cold for my location this time of year. next test I suppose could be 3x AA or AAA nimh batteries.
39 hrs, vBat at 2.54, temp -2.2C. I need to find my multimeter and check that on-board adc against actual battery voltage. Will it make it to 48 hrs? Really was hoping for more, but maybe 5 min isn’t enough sleep.
48 hrs! vBat 2.50, temp 0.5C. Was quite warm most of the day, I’m sure the batteries enjoyed a break from sub zero temps.
66 hrs in, the batteries are still going. vBat at 2.36, temp -1.6C. I’m surprised the ds18b20 is still working, How low will it go!
Final transmission 12:22, vBat 2.34 temp 0.6C. Going to bring it inside and see if warming the batteries brings it back to life.
Question: ds18b20 always in vcc? Me, i cut vcc for ds18b20 with a pin of esp12. When esp12 sleep ds18 dońt use thé batt. I use my ds18 1 month with thIS méthode and 2xAAA with 1 load temp on 10 minutes. Sorry i m french on french iPhone who correct my words
Good point, the 18b was always powered up. Dallas rates the standby current at 750 nano-amps, and active current of 1 mA. I think I was loosing more current to the cold weather than the probe. Thank you for the suggestion, I will try powering the probe from a output on the ESP for my next test.