As a manufacturer of battery powered IoT devices the single most common question we get asked is, ‘How long will the battery last?’  

It’s an understandable and extremely important question as mass scale IoT goes from project phase into an operational phase.  

Navigating the journey of IoT deployments involves various hurdles, from environmental to technical and human change elements. However, the operational phase introduces a new set of challenges, with battery life taking the spotlight. Addressing battery longevity isn’t straightforward – it’s a multifaceted question like ‘how long is a piece of string?’ 

Diving into this topic is like calculating a car’s mileage on a single tank of fuel. It’s not just the tank size, but also the vehicle’s efficiency, load and the conditions that dictate its range. Similarly, an IoT battery’s lifespan is influenced by numerous factors beyond its capacity.  

Let’s explore the elements that drive our IoT devices ‘fuel’ efficiency.  

1. Battery Type

Different fuels, like various battery types, have unique operating conditions due to their distinct chemical compositions – diesel burns differently to petrol to kerosene and so forth. When it comes to batteries, LiSOCl₂ and Li-Ion batteries, common in IoT devices, operate best at different temperature ranges (20-60 Celcius for LiSOCl₂ and 20-30 for Li-Ion). Unlike engines, we can’t control a battery’s operating conditions, so environmental factors like weather conditions directly impact its life. LiSOCl₂ batteries offer a wider operating range than Li-Ion, while Li-Ion compensates with its chargeability.  

2. Battery Size 

The size of fuel tank is an easy one – larger batteries, which are typically measured in Amp-Hours (Ah) or Milliamp-Hours (mAh) naturally last longer than smaller ones, just as a larger fuel tank can support a longer journey.  

3. System Design 

A well-designed IoT device, like a well-designed car engine, will utilize energy more efficiently, ensuring that the battery power is used optimally to last longer. A better designed product will get you further. Unfortunately, this is the one consideration that can’t genuinely be optimised – your hardware partner directly effects this consideration.  

4. System Power Consideration 

With the vehicle completed we now need to consider what you’re powering or towing. A more demanding sensor that is powered from your battery has the same effect on performance expectation as a heavy trailer or camper. There are a vast variety of sensor types out there that have different power requirements. Knowing which ones are ‘heavier’ in current than others will help to understand your battery expectations better. 

5. Payload Size 

Ok, so the caravan is hooked on to the car, but how much weight are you putting in it? The heavier your data payload or data sampling requirement the more your battery life is affected. The reason is simple, it takes more energy to move more payload from point A to point B. We often find that customers start off asking for more data in the short term than what they need in the medium term – akin to the age-old debate of loading too much in the car for the holiday. 

6. Network Coverage and Distance 

Everything’s loaded and we’re ready to go. The road we’re travelling, like the communication network chosen, plays a crucial role. The further the destination the more energy you’ll burn. If your network tower or satellite is further away, you’ll burn more energy. Particularly in rural deployments, understanding this concept is vital to navigate through the generalized assertions about network reach and energy consumption.  

7. Transport Protocols 

The type of road matters tremendously – optimised transport protocols provide less friction, decreasing the energy use in the same way that a smooth tar road consumes less energy than a gravel road. Having clarity on your transport protocol and its associated impact on battery life will assist in making an informed decision.  

8. Network Congestion 

Then there’s the considerations of traffic. The heavier the traffic on the frequency you’re seeking to transmit on, the harder it is for the signal to get through. Unlicensed spectrum (as opposed to licensed LTE or satellite spectrum) typically carries a higher signal-to-noise ratio in city areas as so many sources compete for it. This generates signal-to-noise distortion that makes it harder for the signal to travel from point A to point B, often simulating the stop and start of traffic in its rebroadcast attempts.  

9. Transmission Scheduling 

It’s also important to consider the time of travel relative to traffic – there’s simply less traffic on the road (and networks) late at night and early morning. If your data can jump on the road outside of peak hours the traffic should be lighter, just make sure it’s not too cold at night as that again can affect the battery chemistry. 

10. Network Bandwidth 

The number of lanes on a road is crucial; more lanes can accommodate more traffic, reducing congestion. Similarly, when considering data traffic, transmitting data in smaller, multiple packets instead of a single large one allows more data to be sent simultaneously, minimizing the impact on battery life.  

11. System Updates 

Neglecting to plan for a pit stop or maintenance in your battery life expectations is fatal. Just like your phone, IoT devices need periodic updates for security patches and network configuration changes. Unplanned updates will burn battery and decrease the longevity of the solution, so make sure you plan for services. 

So where does this all leave us? Understanding your use cases should be the top priority for yourself and your digitisation partner.  By understanding the use case, sensible decisions around device type, number of transmissions, time of transmission, networks and protocols will set you up for success in the long run. 

The essential questions you need to ask your digitisation partner

1. How much data do I really need? 
2. What is the optimal battery type and size for your specific use case?
3. How does the device design ensure energy efficiency?
4. What impact will your chosen sensors and data payload have on battery life? 
5. How do network conditions and traffic influence the longevity and performance of the battery? 
6. How are maintenance schedules and updates managed to safeguard against unnecessary battery drainage? 

By addressing these questions, we can gain a comprehensive understanding of the factors that influence the battery life of IoT devices, ensuring that we not only maximize their longevity but also optimize their overall performance. 

And for those of you looking to join the ‘Ten-Year Battery Life Club’ without the small print, here’s a tip: consider extending battery life with an external solar panel, like the Captis Recharge. It’s like providing your device with a continual source of energy, allowing it to draw on sunlight to maintain its vitality. With enough sun, those ambitious claims of a ten-year battery life will become actual, sustainable outcomes.  

Starting a deployment soon? Don’t go into discussions without the Battery Life Checklist – download below.