IoT Device Battery Life

by Andy Slote - Jun 01 2020

All Posts IoT Device Battery Life

For a significant number of use cases, battery-powered IoT devices are the norm. Many of the challenges of extending battery life are apparent. Still, the simplicity of some devices’ processing and communication can enable relatively long lives – ten years or more in some applications.

Rechargeable batteries are useful in implementations where it’s convenient. Tracking vehicles on a dealer lot with this type of power supply, for example, could be practical when staff can see low battery alerts and respond accordingly. The best rechargeable solutions in this kind of implementation with effective power management will last for months, typically rather than years.

For devices with non-rechargeable batteries, some vendors are touting life spans of around five years,   with ten years or more as aspects of the most compelling sales pitches. Battery choice is a factor in these predictions, but the management of power consumption is most important.

Network technologies with the best device battery performance are Low Power Wide Area Networks (LPWANs) like LoRaWAN, Sigfox, or Nb-IoT. The architecture of these networks allows devices to transmit and receive data with a focus on efficiency. In these LPWAN environments, the power level of devices can vary, however. If conditions permit, it is vital to set transmit and receive power at a low level. If it’s not possible to do so, you may need to lower your battery life expectation.

Next, we need to look closely at what the device is doing. Putting a device to “sleep” for most of the time conserves battery. If we can satisfy the application’s needs with a single transmission of a reading per day, the device can “wake up” briefly for this purpose and quickly return to the dormant state. Three or four communications per day are still practical for most LPWAN environments where battery life is paramount. 

Adding location determination, in addition to sensing capability, will draw more power. In remote areas, where many of these devices live, GPS is the method of locating. Just like the frequency of sensor readings, how often GPS is used to calculate a location is an important consideration.   

After deploying a device, any firmware updates will consume battery power. In some LPWAN networks, Firmware Over The Air (FOTA) is not available, which sounds like a significant issue. But, if it is, what is the impact of applying an update to a battery’s life? Building a business case around ten-year longevity only to have a single event reduce it to seven or five can significantly impact the definition of success.

Environmental conditions impact the lives of all batteries, particularly outdoors, where many IoT devices operate. Applications for monitoring conditions in fields where crops are grown are on the rise. These use cases are always candidates for battery-powered devices. To sell the idea, farmers need to know they will get the data they regularly need, with minimal impact from device non-communication. Ten-year battery life can be a valid selling point as long as it is realistic when the high temperatures in a field often exceed 100° F during the growing season (Or occasionally drop below freezing ).    

One of the hottest topics in IoT is the concept of edge processing, which is important to consider when the primary goals are more immediate action and reducing the amount of data sent to the cloud (also resulting in lower storage requirements). In implementations dependent on long battery life, devices are typically relatively simple. Adding an edge processing application may be practical for a network gateway but impossible for a device of this type.     

If remote devices with an absolute requirement for extended battery life are essential to your IoT implementation, there may be options available. There are many things to consider for it to pan out – some you can control and others, frankly, that you cannot.

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