Balancing Battery Life and Reading Frequency

How long will the batteries in my Conserv sensors or existing data loggers last? Well, that depends...

Changing batteries is an unfortunate side effect of the modern world.  Nobody likes it, but to keep all of our devices up and running it has to be done.  If we don't stay on top of it, we'll find that readings were missed due to a dead battery.  This leads to holes in the data, which can make good long term analysis of environmental conditions difficult, if not impossible.

Luckily, modern digital electronics are capable of extremely low power operation.  What this means for us is months or years of not worrying about batteries.  There are a few ways we can extend this even further if we are willing to accept a few tradeoffs.  Which options are available to us depends largely on whether we're talking about an offline data logger, or some kind of wireless sensor.

Offline data loggers come in all sorts of flavors from vendors like IPI (PEM2), Onset, and others.  Some only read one or two things like temp and RH, while others are much more full featured and can log light, UV, and many other environmental agents of deterioration.  With these types of devices, the biggest impact on battery life usually comes from the frequency of readings.  The more frequent the reading, the shorter the battery life.  Some units allow turning certain readings on / off, which can also save battery.

Wireless sensors are a little bit different, and we have a few additional things to think about.  Wireless devices also use a lot of power when they take a reading, but that's not usually the biggest source of power consumption.  With a wireless device, the biggest power drain is transmitting data.  With some devices (such as Conserv's SCS-1) readings are transmitted when they are taken.  With others, readings are taken for a period of time, and then either transmitted as a set or averaged out and transmitted.  Either way, the frequency of transmission matters.  More frequent transmission = shorter battery life.

This is especially true of sensors that use WiFi for their data connection.  WiFi connections are fast, but they also use a TON of power.  Conserv, on the other hand, uses LoRaWAN, a low power, long range wireless protocol.  This means we can send data more frequently and use a lot less power doing it.

If you are seeking to maximize battery life from your sensors or data loggers, you can try to adjust the following:

1. Frequency of data transmission

2. Frequency of readings

3. Which sensor channels are read

Your device manufacturer might have additional options, check your device documentation for more details.