I was recently chatting with a friend of mine about his new hardware startup and how his progress on his new product was coming along. He was building a Bluetooth device and his first run at a prototype only kept his circuit board online for 40 minutes before draining the battery. I’ve noticed the difficulty of many IoT devices is that often they need to run for long periods of time.
Whether it’s something you can wear or a sensor in a smart home environment, IoT devices can have a wide range of power demands from plug-in adaptors to battery-operated. IoT devices and mobile technology are not always used near a wall outlet and will need a reliable and dedicated power source in the form of a battery. Internet-based activities can consume a lot of power - how do you prepare for that with your own ideas?
Why Does Power Use Matter?
Low-power IoT devices are already used in smart homes. Controlling things like the air conditioner, heater, and door locks from your phone or laptop require devices that use a small amount of power and do not eat up batteries.
Some IoT door locks for smart homes have battery lives that span two-years. This is without being hooked into the 110 V AC line for recharging.
Low-power IoT devices are also being used in infrastructure and utility monitoring. WAN-connected meters have long been used by utility companies to monitor civilian power use and report results back to the utility company. Remotely deployed IoT devices that monitor activity at bridges and dams also require a long battery life.
These devices need to be able to gather important data and transmit it over the internet without requiring frequent battery replacement. Although a battery will be the primary power source, this can be supplemented by an emergency backup battery or compensated by an energy harvesting system. Using an energy harvesting system extends the usable lifetime of your devices before its primary battery is exhausted and needs to be recharged or replaced.
Current and Voltage Math Simplified
So how do you choose the right battery for keeping your circuit board online? To begin, you should have a good idea of the total power and current your device needs to run properly. If you aren’t sure, take a look at the datasheets for your components. Manufacturers do their best to include this information with their products and you can get an easy and rough idea by just adding up the current in each component.
Component datasheets will also tell you the voltage required for each of your components. Most components will run at 5 V but this may be different depending on your choices. You’ll want to select a battery that has the right size and voltage while still giving you the largest total charge possible.
Run your IoT device on anything from alkaline to metal halide batteries
Once you have your components selected and you have arranged everything, you can finally power up your device. Look at how long you can run your device before completely draining your battery. You might find that your battery does not hold out as long as you would have liked. If this happens, consider swapping for a different battery, adding energy harvesting, or selecting components that draw lower power.
Batteries vs. Energy Harvesting
When you’re choosing a battery for your IoT device, you need to understand the constraints of the batteries themselves. Keeping in mind cost, dimensions, capacity, and discharge/recharge rates for your battery will help you make your choice. Different chemistries also have different voltage characteristics as the batteries discharge or recharge throughout their lifetimes.
Something as simple as an array of AA batteries or a button-type battery can bring your device online. Some smart home devices can run on AA batteries for years without requiring replacement. If you want to supplement your power source with energy harvesting, you can add solar cells, piezoelectric generators, or thermoelectric cells to convert light, vibration, and heat energy into electricity.
If your device uses a fair amount of power and you are suspicious that it will need to recharge frequently, pairing up rechargeable batteries with energy harvesting systems may be the answer. Companies are developing systems specifically for IoT devices that use energy harvesting, and these systems can potentially keep your device ticking along for years without replacement.
Battery or otherwise, you’ve got the capability to keep your device running
When working on a printed circuit board, no matter where the technology comes from, having strong PCB design software will enable you to make sure your printed circuit gets to that printed stage. Look for PCB design software that can create the power supply layout you need, manage layers, buried vias, adjust hole sizes and plan copper plating and solder mask for manufacturing. Look for Altium Designer.
If you want to learn more about how Altium Designer can be the board design software for you, talk to an expert at Altium today.
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