The Financials of Smartphones and Batteries

I was recently pricing a new smartphone. Standard Samsung or Apple phones start around $800 (plus taxes and fees, a screen shield and a new case). The most common reason for replacing them is a dying battery.

Phones normally last two or maybe three years, depending on who you talk to. I use my phone a lot but after nearly five years, it’s still running well. Some years ago, I did some research on phone batteries and found that with some discipline, you can extend the life of a phone significantly. Here’s what I learned.

The short course on phone life is that batteries are stressed by how you charge them and by the demand you put on them. Heat is also a source of battery trouble. Here’s some further details if you’re interested in potentially saving yourself hundreds of dollars on phone costs.

The information on batteries can vary, partially because smartphone retailers want to present their phones as easy to use, and this often means a shorter life. Further, they have more than a little interest in you buying more phones.

But the independent data on phone batteries is fairly consistent. In spite of today’s battery hype, little has changed in the technology behind the lithium-ion batteries used in phones. And the rules that apply to your phone battery mostly apply to any lithium-ion battery, whether your watch, laptop or electric car.

One of the best ways to extend the life of a lithium-ion battery is in how it is charged. They are most efficient when working at around 50% capacity. Draining a battery below 20% is one of the worst things to do. It’s also best not to charge it much past 80%.

Charging it to 100% and then running it down below 20% is a sure way to shorten your battery’s life. Some phones now come with a system setting that will stop charging before it reaches 100%.

It’s also good to use chargers approved for your phone. Most off-brands work fine but some can overcharge a phone. You are fine charging your phone through your computer or laptop. Finally, slow charging is better than fast charging. There may be options on your phone to only allow slow charging.

There’s one last charging issue, and that is a parasitic load. Do not charge your battery while it is also being drained significantly, such as watching a video or gaming. Charge your battery when it is mostly idle. In fact, the best way to charge a phone is in short, slow periods when the phone is idle, keeping the battery somewhere in the middle of its capacity.

The next battery issue is drain. In general, the less you drain it, the longer your battery will last. Balancing this with your needs can be a challenge.

One of the biggest uses of the battery is the screen. There are some things you can adjust, such as reducing the brightness and having a shorter screen timeout (auto-lock).

Another problem can be Wi-Fi, Bluetooth and GPS. They can be a silent battery killer if you’re in an area with spotty coverage and your phone is working to keep itself connected. If you know you don’t need any or all of them, shut them down.

Another heavy drain on phones can be any of several apps, such as Facebook, Messenger and Instagram. They can be constantly operating in the background even when you aren’t using them. If you don’t need them, turn them off.

Finally, if you’re running low on your battery and can’t get it recharged, then shut down any unneeded apps and turn your phone to a power saving mode. Note that turning it off isn’t necessary. An unused phone without background apps running uses very little power.

The last big problem with batteries is heat. Lithium-ion batteries do not like heat. They are fine with cold (although their short-term power reduces when cold) but heat is all bad. Keep them out of the sun and out of a hot car. Heat is one of the reasons to avoid fast charging.

After this, there are potentially dozens of things you can do to extend a battery’s life a bit more, such as monitoring applications, keeping your software updated, limiting the use of camera flash, turning off vibrations and reducing screen refresh rates. But now you may find yourself more engaged in not using your phone than in trying to help its battery do its job well.

If you prefer, there can be some value in considering having a battery replaced, and possibly even doing it yourself.

But in the end, a battery and your phone will both eventually die. In my case, the manufacturer quit providing security updates, forcing me to replace it. Fortunately, I got over a 50% rebate for an old phone, so all was well.