I used to replace my phone every two years. Not because I wanted a new one — because by year two, the battery would not last past lunch, the screen had a crack in the corner, and the whole thing felt sluggish. I assumed that was just the lifespan of a phone. Then I watched a friend use the same iPhone for five years, and I asked her what her secret was.

The Battery Is Everything

The number one reason people upgrade is battery life. A phone battery is rated for about 500 full charge cycles before it drops to 80 percent capacity. If you charge from 0 to 100 every day, you hit 500 cycles in about a year and a half. But if you never let the battery drop below 20 percent and unplug it at 80 percent, the same battery can last 3 to 4 years at near-full capacity.

The sweet spot is keeping your battery between 20 and 80 percent as much as possible. Lithium-ion batteries degrade fastest at the extremes — fully charged or fully drained. I now charge my phone for 30 minutes in the morning and 30 minutes in the evening, never overnight. The battery on my current phone is at 91 percent health after two and a half years.

Small Habits That Add Up

• Use a quality case and a screen protector. A cracked screen is the second most common upgrade trigger. I spent 30 dollars on a good case instead of 800 dollars on a new phone.
• Clean the charging port. Lint builds up in the port and prevents the charger from making good contact. Your phone is not charging slowly because the battery is dying — it is because the port is clogged. Turn off the phone, use a wooden toothpick (never metal), and gently scrape out the lint. The amount of compacted pocket fuzz that comes out is genuinely alarming.
• Delete apps you do not use. Old apps run background processes, send notifications, and eat storage. A phone with 5 GB of free space runs noticeably faster than one with 500 MB.
• Turn off background app refresh for apps that do not need it. Instagram and Facebook do not need to fetch new content every 15 minutes when you are not looking at them. This saves battery and processing power.
• Replace the battery instead of the phone. A battery replacement at a repair shop costs 50 to 80 dollars. That is one-tenth the price of a new phone, and it gives you another two years.

When It Is Actually Time to Upgrade

If the phone stops receiving security updates, that is a real reason to upgrade — running an unsupported operating system is a security risk. If a critical app you need for work no longer runs on your version of iOS or Android, that is legitimate too. But “the battery does not last all day” is just a battery problem, not a phone problem.

I am on year three with my current phone. It runs fine. The battery is still good. The charging port is still clean. The math on what I have saved by not upgrading is kind of embarrassing when I think about how many phones I bought before I figured this out.