Look around: mobile isn’t the future, it’s the present. The world is becoming increasingly connected through new hardware innovations. We’re witnessing new battery-powered creations in categories that didn’t exist a decade ago—tablets, AI assistants, smartwatches, and more. Plus, startups are getting their wearable, handheld, and portable devices from concept to crowdfunding faster than ever.
If you’re developing a new product, chances are you’ve invested a great deal of time in targeting your market, building your architecture and fine-tuning your application and user interface. But have you thought long and hard about how to power your new device?
Choosing the right battery and charging technology can significantly impact your product's user experience, aesthetics, and functionality. You should consider these factors early on in your product roadmap. If you’ve been unsure whether to go with wired or wireless charging, here are a few things you should consider.
Wireless power standards come of age
When USB emerged as the de facto standard for wired charging technology, design choices became easier. At that time wireless charging standards were still in their infancy. Developers who wanted to employ wireless power had to choose from a multitude of standards that varied widely in range and wattage.
Much has changed over the past five years. Today, the Qi standard, first published in 2008, has emerged as a fixed standard for wireless charging. When Samsung implemented Qi in its Galaxy smartphone, the standard rapidly spread across a wide range of wearable and portable devices.
People today can choose from an assortment of wireless Qi devices with a wide variety of relatively inexpensive chargers. The Qi standard is not only easy to implement, but highly flexible. It can scale in cost and power levels ranging from 1-15 watts. Incorporating the standard is easier than ever because many suppliers now have turnkey proof-of-concept reference design kits.
While it looks like the market is moving toward wireless, take the time to understand your choices and consider the pros and cons of choosing a particular charging technology.
Pros of going wireless
Mass adoption: As the technology matures, the efficiency and quality of wireless power transfer is increasing. For example, Qi wireless cell phone chargers are now a standard option in many electric and luxury cars. Soon they will be available in midrange vehicles, too, so your backer will have a perfect place to bring your invention with them on the go.
Falling prices: The cost of wireless charging technology is dropping fast, especially for high-volume manufactured products. For example, as sales of smartphones grow, the per-unit cost of implementing wireless connections has dropped dramatically.
Charging flexibility: Wireless chargers are capable of charging more than one device simultaneously. Also, they don’t require cables between the device and charger, which is convenient.
Pros of going wired
Ease of development: Most engineers have some knowledge of basic wired power solutions. The learning curve is short, and you can get your project up and running quickly because design references are plentiful.
Tried and true: For now, wired charging is cheaper and more reliable than wireless power. You may want to launch an initial version of your product with wired power, to get on the market fast. Then, you can hatch plans for an enhanced version with wireless capability.
High stakes technology: For demanding or time-sensitive applications, sometimes wired provides more consistent, dependable performance. You wouldn’t want a wireless microphone to produce bad quality sound just because the wireless charging pad was on the fritz.
Cons of going wireless
Higher cost: Wireless power transfer is more affordable than in the past. However, it will continue to be more expensive to implement than wired power connections. An important consideration is whether your customers will pay more for wireless technology.
Lower efficiency: Wireless technology is not as power efficient as an equivalent wired connection. They often take twice as long to charge as wired ones. This could affect customer adoption.
Wear and tear: Wireless technology can be harder on internal systems. For example, current wireless charging technologies can subject batteries to additional heat and stress. This can lower device performance and life expectancy.
Cons of going wired
A different kind of wear and tear: From exposed USB ports to frayed cords, there are many places where wired power can break down. Proprietary power cords can create additional costs and headaches for your customers.
Less ruggedized: Wired technology doesn’t have the flexible options for full ruggedization or water-proofing that wireless power does. Its open ports can limit the ways it can be deployed.
Getting left behind: As the world continues to move toward wireless, you risk having legacy wired systems intermingling with new wireless advances. For interoperability, you’ll need a good team to help navigate how the two power systems work together as you transition from one to another.
Make sure the battery matches the charging option
We’ve talked about charging quite a bit. But whether you’re developing the next great AI robot or just a simple fitness tracker, you’ll usually be charging a battery along the way.
Countless battery types have emerged over the years. Lead acid technology dates back to the 1800s, yet it’s still used heavily in automotive and solar applications—so you’ll likely not come across it while researching applicable options for an instrument or wearable.
Nickel-metal hydride technology came along in the late ‘60s and remains a popular choice for consumer electronics and electric vehicles so it might be nice to consider.
However, for portable applications, these batteries are increasingly being eclipsed by lithium-ion, which offers superior power density and faster charging—at a higher price that’s usually worth paying. Lithium-ion batteries are common in consumer electronics and are gaining popularity in automotive and aerospace applications.
Which of these batteries is right for you? You’ll need to balance size and weight with cost, capabilities, and safety. Here are a few important characteristics that you should consider when exploring battery options.
Get comfortable with two phrases: battery gauging and cell balancing. Battery gauging refers to a battery's ability to accurately assess and report its energy levels. This is an essential feature for most consumer electronics applications. Cell balancing is crucial to maximizing the capacity and extending the life of a battery. These attributes can greatly impact a user's experience of your product.
Battery configurations, also known as topologies, can have a big impact on the complexity and costs of your designs as well. Centralized topologies employ a single controller connected to multiple battery cells, each with its own communication wire. It's an economical approach that is a good choice for most consumer electronics products such wearables, connected home sensors, and even drones. Distributed topologies feature separate controllers for each battery cell. This is the most expensive option but also the easiest to install, and most expandable. Modular topologies provide a compromise between the centralized and distributed configurations – they use several controllers, each connected to a small number of cells. These topologies are most often used in products that require networks of batteries, like electric cars.
It’s all about providing the best experience
Understanding the pros and cons of each power option is key to realizing the full potential of your new product—and delivering the best experience for your eventual backers. Wired power is a strong option for developers that need to get to market fast and require an inexpensive, proven solution. For products where convenience and future compatibility are paramount, you can move forward confidently with standards-based wireless power. To get the most out of the options you choose, you also need to consider the physics and specifications of your power and charging systems as you architect your product. This often means using a tried-and-true lithium ion battery with a simple charging configuration.
While there’s no such thing as too much knowledge, it pays to go to credible sources and strong communities of creators to determine the path that’s right for you. You can learn more about what other creators are doing on the Hackster.io and element14.com communities, or reach out to some of the partners listed on the Hardware Studio homepage.