Tired of keeping a charger in every room because your laptop battery can’t hang? Fed up with your “portable” computer that can’t leave your desk for more than 30 minutes? Or maybe you’re just sick of fighting for the outlet-equipped seat at your favorite coffee shop, missing out on that choice seating only useful to patrons with plenty of battery life. It doesn’t matter who you are or how well you treat your laptop’s battery—it will eventually die. It’s normal. What’s not normal is that most people don’t know how or when to replace it themselves.

“I followed the directions, had all the tools (courtesy of iFixit.com). The fix was super easy and cost effective! Check iFixit.com before sending things off for repair!”—Jeff Hughes: MacBook Air 13” Mid 2011

The good news is that if you have a Mac laptop—anything not in the Retina line—we pinky- promise that replacing the battery yourself is easier and faster than you think. (Don’t worry, Retina owners, we’ve got a battery solution for you, too—it just takes a little more TLC to do the repair.) Not all batteries are created equal—every battery can handle a specific number of charge cycles before its performance starts to suffer. That makes knowing exactly when to replace your battery unclear (unless your battery has completely failed, then you most definitely know). While there’s no hard and fast rule to tell you when to replace your battery, there are some clear warning signs you can look out for.

Battery Service Warning

This one’s easy. When your MacBook tells you that it needs a new battery, you should listen to it. Click on the battery level in your top menu bar to bring down a drop-down. At the top of the menu, you’ll find the TL;DR version of your battery’s current condition. If it says “Replace Soon,” “Replace Now,” or “Service Battery,” it’s time to look into a replacement. Your MacBook was nice enough to ask—be a good friend and treat it to a nice new battery.

Image Source: CNET

P.S. With a little digging, you can find some more details about your battery’s health. Check out Apple’s instructions here. The Power section of your Mac’s System Information menu lists how many charge cycles your battery has been through. Compare that to the maximum cycle count for your model, listed on Apple’s instruction page. If the number of charge cycles used is close to the maximum number of charge cycles for your model, you should start thinking about replacing the battery.

Low Battery Run-Time

Remember when you first unplugged your new MacBook? Who could forget that sweet feeling of freedom as you whiled away the hours, anywhere you pleased. Are you now only able to while away a few minutes before your MacBook demands to be charged? Sounds like it could be time for a new battery. How low you want to run your battery is a really personal preference—and some users like to keep things spicy. For those that prefer a milder MacBook experience, a good rule of thumb is to replace the battery when its run-time is down to 25 percent of the brand new run-time.

Unexpected Shutdowns

It’s not just iPhones that unexpectedly shut down—all of our battery-powered devices can unexpectedly shut off when the battery lives past its expected shelf life. If your MacBook turns off when you don’t want it to, it could be because the battery is out of juice. If this happens often—and shortly after you charge it—that’s a clear sign that it’s time to replace the battery. A MacBook can also turn itself off if it overheats or encounters certain errors. Be sure to test your laptop while it’s plugged in order to determine if the shutdowns are purely a battery issue.

Overheating

If you can’t handle the heat—get a new battery in your MacBook. Well, okay, it’s a little more complicated than that. Any number of hardware or software issues can cause your MacBook to overheat. However, if your MacBook overheats quickly while performing small everyday tasks (and especially if it also experiences any of the above symptoms), the culprit may be a faulty battery.

Extra Credit Math Time!

For those of you who want to monitor battery life a little more proactively—good news! You can do that with just a little math. Follow the steps here to reach the “Battery Information” section in System Information. Multiply the “Full Charge Capacity” by the “Voltage,” and then divide that number by one million. Now you have your battery’s current capacity in watt hours, and you can compare it to the original capacity (the “Full Charge Capacity”) to see if your battery’s still up to snuff. Here’s the equation with units:

Your battery was designed to be used, so don’t feel like you need to obsess over monitoring its capacity. Just be sure to replace it before you end up like this guy. But if now’s the time, be sure to check out our Mac Laptop Battery Fix Kits. We just re-designed them to include all the parts and tools you need to do the swap. Just remember to recycle that old battery while you’re at it.

New iFixit MacBook Laptop Battery Fix Kit

Adam O'Camb is a technical writer and teardown engineer with iFixit.

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