Slow Versus Fast Charging: How Wireless Power Can Extend the Life of Rechargeable Batteries

Is Faster Always Better?

If you were asked, “Which is better, fast or slow?” Your immediate answer would likely be fast, because this is a fast-paced world (usually) and getting to where we need to go or what we need to receive -- whether we’re taking digital or physical -- faster is typically a priority. We all know the instant gratification urge.  Tortoise and Hare RaceRemember that children’s fable of the tortoise and hare race? The turtle wins in the end. Now your more nuanced answer might be “It depends,” because you think about that time you ordered groceries and they arrived earlier than you expected and they sat on your doorstep for a few hours. Or the time your kids rushed through their homework, only to get it wrong.

The Efficiency and Convenience of Steady and Slow

 Amazon figured out that slow might be better in some situations, and provides an option for slower package delivery, sometimes with a promotional perk. Slower delivery alleviates stress on resources, which enables the company to provide better, more cost-efficient service. Or, as in the case of the Coronavirus pandemic, slower delivery on nonessentials allows for faster delivery of essentials, like food perishables or toilet paper (if they have it).

When it comes to filling rechargeable batteries, the same rules apply. A fast charge is nice if you’re in a hurry, needing to unplug and go. But if it’s charging at your desk, during a 5-hour drive, or while you’re sleeping, it doesn’t really matter if it charges fast – especially if there’s a downside.

 In fact, a slower charge over time can provide a hidden perk: A longer battery life. More charge discharge cycles before you have to chuck the battery.

The Hidden Perk of a Slow Steady Charge: A Longer Battery Life

 Classic combustion engine car owners already know this. A continuous “trickle charge” on their infrequently driven vehicle’s battery is much better than allowing the battery to die and be jumped over and over, which leads to more frequent battery replacements. A steady, low trickle of juice allows the battery to always be topped up and avoids the wear-and-tear of frequent power deep discharges.

The same is even more true for electric vehicles: “Aggressive charging will decrease your battery’s lifespan,” says The Next Web. “Scientists have found that continually using high-powered, fast-charging points can decrease the life of EV car batteries.”[1] That may be in part because fast charging causes a lot of heat, which can stress the battery.

And, yes, it applies for small devices, like smartphones and wearables, too. The gentler the charge, the longer the rechargeable battery’s lifespan. In fact, most rechargeable batteries have an internal system that will slow the amount of power accepted (or charging speed) after about 80% charge, to prevent overheating.[2]

 What does this all have to do with wireless power?

Wireless Power Extends the Life of Rechargeable Batteries

Rechargable BatteryRF-based wireless power, like Cota, is designed to not only provide power directly to devices without the need for a battery, but also efficiently charge up rechargeable batteries. Wireless power over-the-air and at a distance acts very much like a trickle charger for a car battery, so your battery is always charged up. Steady as she goes.

Wireless power provides a continuous background level of energy to the devices of your choice automatically and without the need for charging pads, wires or cables, or stopping what you’re doing to plug in.

In a world where wireless power and wireless charging are ubiquitous, fast charging won’t mean much anymore, because wherever you go, your devices will be receiving that background, steady stream of power to keep those rechargeable batteries at full capacity.

When we, as a society, switch to continuous charging with wireless power, we won’t run into that problem of an eventually sluggish rechargeable battery performance in our computers,  phones, wearables, and other handheld mobile devices nearly as often. Rechargeable batteries will last longer, which will reduce use of environmental resources, as well as the inconvenience and expense of replacing them. 

The point is, when faced with the decision of choosing fast over slow, remember that fast isn’t always better. Especially when it comes to preserving battery life. Or when doing homework. The steady-as-she-goes turtle does pull ahead in the end.

Do you have a product that uses a rechargeable battery system, and you’re considering  wireless power as an efficient, innovative solution to keep them charged up? Let’s talk.

[1] https://thenextweb.com/shift/2020/03/13/scientists-fast-charging-destroys-electric-vehicle-batteries-tesla-panasonic/

[2] https://www.consumerreports.org/smartphones/plugging-old-phone-chargers-into-fast-charge-smartphones/

Sign up for Ossia's Monthly Newsletter