There has been a steady increase in the use of mobile devices to access the internet. In fact, as of December of 2022, Statcounter found that just over half of web traffic is from a mobile device. To accommodate these needs, VPN’s are available not only as desktop software, but also as a smartphone app. The use of these apps make it quite simple to control the VPN.
While smartphones are convenient and portable, they do have some downsides compared to more traditional PC solutions. Leading these drawbacks is that they have limited battery life, and there is little point to having a mobile device that constantly needs to be tethered to a wire to keep it charging.
What is VPN battery drain?
A VPN accomplishes the goal of privacy by creating an encrypted tunnel to a dedicated server run by the VPN service. This means that any data sent via this tunnel is encrypted, and at either end- both the VPN server, and the client mobile device, there needs to be encryption for data entering the tunnel, and decryption for data exiting the tunnel.
The process of encryption and decryption, usually at 256-bit, requires mathematical computations to ensure this high level of security. With modern CPU’s, this can be accomplished quickly and uneventfully without a noticeable delay. However, all of this additional math on the data to be sent, and then again when the response is received does take its toll. Namely, this additional data processing uses up the precious battery life of the device, and goes by the term ‘VPN battery drain.’ Estimates put it at about an extra 5% of battery life drained over a given amount of time for the data usage, compared to not using the VPN on the device.
While the drain from the data connection is the more obvious consumer of battery power, there is also another more subtle one. This is the VPN app running in the background that consumes power. Also keep in mind that the more popular VPN’s will have a better developed app with minimal power usage, some others may be less efficient, and suck up more power.
Now that we have identified the problem of VPN battery drain, let’s look at some ways to address it. After all, nobody wants to end up with a battery depleted device.
Connect to Wi-Fi
Every smartphone has two ways of connecting to the internet: the cellular modem, and the Wi-Fi. When out and about, there is little choice mostly to use the cellular connection.
However, when at home, work, your local library, and the coffee shop, it is worth the effort to connect to the wireless internet connection. In addition to the benefits of using less data on your monthly data plan, and also the generally faster throughput speeds, there is also one more - battery life. This is due to the fact that Wi-Fi is a lower power connection to a cellular one, and therefore affects the battery life less.
Part time VPN
Using a VPN connection does have many benefits, such as security and privacy. While some would advocate for using it whenever you are online, for those that wish to prioritize battery life there is another approach. This is to toggle the VPN connection on whenever it is needed, say to secure a financial transaction when connected via public Wi-Fi, and then to turn it back off when doing something less sensitive, such as watching a YouTube video.
This part time use of the VPN is a more balanced approach, with the use of the VPN when needed, without incurring the battery life penalty at all times for the data transferred which these smartphones constantly do.
The VPN service keeps the data safe by creating the encrypted tunnel between the VPN server, and the client device. Most services encrypt it via a 256-bit algorithm, which meets government standards for “Top Secret,” yes like in the spy movies.
As you would imagine, this does involve some heavy duty math via an encryption cipher to send it via the tunnel, and also to decode it at the other end. Realize that there are some options in terms of this encryption and decryption process that will impact smartphone battery runtime.
One simple option is to encode it to a lower level of encryption, such as 128-bit. This then requires less processing power and will provide more battery life. However, the realization is that the data is less secure in the tunnel, so this may not be appropriate, as you are likely using the VPN for a good reason in the first place.
Another variable to manipulate, and arguably a better one than going to a lower encryption level is to pay attention to the encryption protocol. For years, most VPN’s offered, and users selected the OpenVPN protocol, felt to be secure, as it was an open source protocol. An additional benefit is that it was designed to hide the encrypted tunnel, and make it appear more like regular internet traffic. However, OpenVPN has been around for a while, is computational heavy, and is likely to consume a higher amount of battery life.
Some users have turned to the older protocols, prior to OpenVPN. The benefit is that these run lighter, and therefore will impact battery life less. However, they are considered less secure as they are not the modern ones, and this is why users moved on from them for the most part years ago.
Given these challenges, there are some better options as the latest VPN encryption protocols have been designed from the ground up to maximize battery life via lower power consumption. One popular option is the WireGuard protocol that is an open source protocol. With its lighter codebase, a good number of VPN services now offer this option.
Finally, some of the larger VPN services have even designed their own VPN encryption protocol. An example of this is the ExpressVPN Lightway protocol, which is designed to connect quickly, run efficiently and therefore minimize the impact on VPN battery drain.
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Jonas P. DeMuro is a freelance reviewer covering wireless networking hardware.