I last blogged about this in December 2013 when the second version of my ATmega328 & DS18B20 based temperature sensor, installed on 29 December 2011, had just reached the 2 year mark on the original set of batteries. That’s pretty good going and I’d have been happy with that but how long would it last until those Energizer batteries needed replacing? Well I found out in March of this year when it finally started to report erroneous readings, yes that is over 3 years on one set of AA batteries. To be honest, I did have a false alarm a few weeks prior when it started to transmit very irregularly but it recovered from that, presumably due to the increase in temperature affecting the battery capacity.
Like I said in the last post on this, this particular sensor was positioned where it didn’t have the best signal so it often had to retransmit and being the oldest running one it had started off with some pretty poorly optimised code and was off to a bad start to begin with. Needless to say I am more than happy with this result and I only wish I had logged the battery voltage over time of some of my other sensors but as it is they only report the current level so that Node-RED can alert me if one gets low.
— Nathan Chantrell (@nathanchantrell) April 7, 2015