Enovix

Nov 30, 2021

4 min read

Powering Our Mobile Future

Part 1: Battery Life and Consumer Satisfaction

The first commercial lithium-ion (Li-ion) battery, commercialized in 1991, significantly increased energy density compared to the nickel-cadmium battery. Without this step-change increase in energy density, the brick-size cell phone of the 1980s would never have evolved to today’s sleek, sophisticated smartphones. Through 2020, the Li-ion battery has only increased its energy density on average less than 4.4% annually.

The equation below shows the relationship between battery capacity (supply) and consumer satisfaction (demand). Survey after survey has revealed that the number one consumer wish for their mobile devices is better battery life. But despite their displeasure, consumers continue to purchase over a billion mobile devices each year. That’s because battery life — the time between required battery charging — is only one factor in the overall satisfaction of consumers with their mobile devices.

Source: Enovix Corporation

Battery Life

Closer examination reveals that battery life is first a threshold and then a graduated factor in overall consumer satisfaction. In other words, there is a minimum time between required charging of a device that consumers find acceptable. Below this threshold, consumers will not adopt and use a device en masse. However, above this threshold, battery life competes with user experience and device functionality for over­all consumer satisfaction.

For example, a compar­ison among U.S. smartphone customers by the Amer­ican Customer Satisfaction Index (ACSI) in 2020 shows the Apple brand with the highest overall satisfaction rating of 82 , although the battery life of the iPhone 11 was 11:16 (hours:minutes) and that of the iPhone 11 Pro Max was only slightly better at 11:54. Conversely, the Moto G Power was top rated for battery life at 16:10, but in order to have a $200 price point, it didn’t offer many bells and whistles.

On the other hand, mobile device producers un­derstand that dropping below a consumer expected threshold for battery life can adversely affect mobile device adoption and mass-market use. Evolution of the Apple watch is an example of how insufficient battery capacity can adversely affect battery life, functionality, and, ultimately, product adoption and consumer satisfaction.

When Apple introduced its second-generation smart watch in 2016, it did not include an expected direct cellular network connection feature because, as Bloomberg reported, “current cellular chips con­sume too much battery life, reducing the product’s effectiveness and limiting user appeal.” Apple had to delay adding functionality that would untether the Watch from the iPhone because of insufficient battery capacity. Later that year International Data Corpo­ration (IDC), a global provider of market intelligence, reported that battery-life frustration was one factor stalling smartwatch market adoption beyond early enthusiasts.

When the Apple Watch Series 3 was introduced a year later, in 2017, a direct cellular network connection fea­ture was included. But some reviews of Apple Watch performance were negative. Joanna Stern’s review for The Wall Street Journal was representative: “You’re lucky if the battery allows you to roam on cellular for longer than half a day — especially if you’re making calls.” She concludes, “Unless you plan to carry around a 5-pound backup battery in your bag, living a full day with just the Apple Watch isn’t happening.”

A year later, in 2018, when the Apple Watch 4 was introduced, Ms. Stern had changed her tune, “The Series 4 feels like it has been through a needed maturation process, with refinements to the screen, the battery, the cellular connectivity, and more.” A combination of increased battery capacity and energy-efficient chips improved user experience and functionality (display and connectivity) as well as battery life — a win-win.

The following year, in 2019, she described how battery performance could enhance a basic smartwatch feature. “With the always-on display, I was able to make it through a full day — 7 a.m. to 11 p.m. — with just under 10% battery left. But when I disabled the always-on feature in settings, I had 30% remaining — just like my Series 4.” Better battery performance can improve consumer satisfaction by providing a choice of greater functionality or longer battery life, but only after it meets minimum battery life expectations.

Regarding battery life, consumers would prefer their mobile devices to perform for days or weeks between charging, and some fitness trackers do. But, for de­vices with greater functionality, such as smartphones and smartwatches, there is a consumer expectation that battery life must be sufficient to get them through a normal day without the need to recharge.

In the next post, we’ll look at the role of user experience and functionality in mobile device consumer satisfaction. If you would rather not wait, download and read our white paper, “The Value of a Step-Change Increase in Battery Energy Density for Consumer Mobile Device Satisfaction.”