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Battery Size Matters: Fundamental Considerations for a Wireless IoT Sensor Product

[ Edited ]




According to a recent report by Gartner, a typical family home may contain more than 500 smart devices by 2022 (Gartner news, Sep 8, 2015). Low cost IoT technology can make home automation products smarter, but features like wireless transceivers and innovative sensors which make this possible need a lot of energy - most of which is powered by batteries.


The challenge for designers then is to build a small-form factor product with the cheapest bill of materials (BOM) and that can operate reliably for several years without battery replacement.



Five Fundamental Considerations for a battery-powered, wireless IoT sensor product

In keeping with the above, a few things should be kept in mind when trying to meet the design challenge.


First, it is imperative to understand the target market - and the corresponding requirements on cost, reliability and battery life. In some cases designers may have to make a trade-off between some extremes, for instance between subscription-based service providers and do-it-yourself home automation.


Second, choosing which protocol to use significantly affects battery life - wireless, Bluetooth or Zigbee etc. Each of these is suited to a different category of smart devices and the choice should be made accordingly.


Third, knowing how often the device communicates can help the designer determine the required transmission strength, duration and duty-cycle between sleep and active states.


Fourth, taking into account that each application requires a certain type of sensor and accordingly selecting an MCU can save both power and cost.


Fifth, acknowledging that there are space constraints can help when looking at different options for stored power, i.e. batteries. In addition to size (smaller batteries store lesser power than larger ones), chemical composition is also a factor (alkaline or lithium batteries). Each has its pros and cons and suitability varies for different devices, which is why it is always good to have an overview as below:






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