Battery life is the top concern for smartphone consumers and it’s easy to understand why. Who hasn’t experienced a smartphone battery draining at an unexpectedly fast rate? It’s a frustration that translates to the many smart devices that make up the IoT ecosystem today, especially smart medical devices.
When the battery in these devices drains too quickly or even dies, the outcome can be much more than a frustration (see Figure 1). A low battery in an implanted medical device might manifest itself as patient fatigue. In a patient monitoring system, it could result in a critical alert or medical data not being delivered to a healthcare professional, and that could be fatal.
With 40% of all IoT technology expected to be health related by 2020, and a sizable amount of that battery operated, it’s now more critical than ever for IoT product makers to pay close attention to battery runtime.
Need another reason why battery life should be a critical design consideration? How’s this: The cost of replacing batteries is often higher than the cost of the IoT device itself.
Make no mistake, developing battery-powered IoT devices doesn’t just involve replacing a power plug. To truly maximize battery life, product makers must perform battery drain measurements and obtain a thorough understanding of the device’s power-consumption patterns. That testing must be accurate and simulate the real world in which the device will operate. Failure to do so can come at a great price in terms of the company’s brand and pocketbook.
Here’s a look at four tips today’s product makers can take to ensure their IoT devices have a long battery life.
1. Take your device to the extreme … environments, that is
Battery life is dependent on several factors, including temperature, humidity and user behavior. Heat, for example, will kill a battery. And if the battery is stressed with frequent discharge, service life can drop dramatically.
To ensure environmental conditions don’t adversely affect battery life, its power consumption must be measured across the range of temperature, humidity and other conditions it will experience. The environmental and temperature extremes it will encounter during shipping and storage also must be considered. Having to change a device’s battery in an extremely hot or cold location is never a desirable task.
2. Test in difficult electromagnetic environments
A device may work perfectly when tested on a bench in a laboratory only to fail miserably in the field. That’s because transmission retries drain batteries and a transmission power that seems sufficient in the lab may be drowned out in a congested electromagnetic (EM) environment. Crowded spectrum can also impact transmission efficiency.
To prevent these issues:
- Test for co-channel and adjacent channel interference rejection, and for immunity to hostile and inadvertent interferers, including EM fields produced by motors and other heavy industrial equipment
- Ensure compliance with FCC requirements
- Keep frequency accuracy as tight as reasonably possible
- Avoid unnecessarily powerful transmissions
- Ensure the device transmits only when it has useful data
3. Don’t overlook cybersecurity
Cybersecurity is one reason consumers are reticent to embrace the IoT, and with good reason. These days even a smart thermometer is susceptible to hacking. But, there’s another reason security should be top of mind for today’s product makers: Lax security impacts battery life. A person with bad intent can intentionally try to destroy an IoT installation by draining the batteries of its sensors. Even if that is not the explicit intent of the hacker, any unexpected activity places an additional load on the battery and can cause it to drain quicker.
Avoiding this outcome means making device security a top priority. Relying on users to change a device’s default password can’t be the only security measure implemented. Vigorous device testing using an appropriate security test solution can help product makers quickly identify any potential security gaps and increases their confidence in a device’s ability to fend off cyberattacks.
4. Make the right measurements using the right technology
IoT devices have very dynamic current, with sleep or hibernate modes in nA or μA, and transmit modes measuring mA or A. Such variability makes accurately capturing current difficult. To do so, engineers must be able to measure low currents and switch to high current measurements quickly.
An instrument with demonstrated precision and that offers either dual ranges or seamless ranging is often the best bet for avoiding measurement errors due to range changing. Instruments with insufficient measurement bandwidth should be avoided. They severely degrade current measurements and may even cause the engineer to miss fast — transient — events that briefly draw an amp or more. Either scenario can result in a device failing prematurely.
Without question, battery life can make or break an IoT device. Fortunately, by following these four tips, product makers can begin to make the smart choices needed to ensure their devices have a long battery life and the greatest chance of success in IoT.
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