I suspect that Apple's design team spent an absurd amount of time and money developing the way a MagSafe connector clicks into place when you plug in your MacBook Pro or MacBook Air. Given that combination of magnetic attraction – the metallic meeting of plug and connector, and the sudden flow of electricity – there's nothing quite as satisfying as plugging in your MacBook. From the clean look, to the solid feel, to the perfectly simple works-every-time design, it's really a great feeling.
Unless, of course, it doesn't work. No amount of engineered sound and carefully designed feel can make up for the frustration of a laptop that won't charge when plugged in. But wait! Don't go running off to the nearest Apple Store just yet. You could save the Geniuses a bit of work (and save some travelling yourself) by running through this quick checklist of possible problems that you can diagnose right now, in your own home.
1. Are you plugged in?
It sounds silly, but you need to make sure that the MacBook is actually plugged in. No software tweak or hardware repair can make a disconnected laptop magically power on.
Before checking anything else, then, you need to ensure that both the power plug and MagSafe plugs are firmly seated. Is there debris in the MagSafe port preventing a clean connection? Is the power adapter fully plugged into the outlet? Check the AC adapter brick and verify that any removable cords are fully inserted. Finally, find out whether the problem might not be with the laptop at all: Try plugging the power cord into a different outlet to see if you've got a short or a blown fuse.
At this point, we've determined that it's not just user error causing the problem. There is a real issue with powering the MacBook; now it's simply a matter of figuring out where the problem may be. That begins with eliminating where it isn't. We'll start with the most common and easy-to-address issues.
2. Check the battery
A simple way to check the integrity of the battery is to remove it entirely and try plugging in the laptop. If the laptop powers on properly, the problem was likely a bum battery.
Obviously, this step only applies to older MacBooks with user-accessible batteries. If you've got a MacBook released in the last four years, move on to the next step.
3. Breaks, burnout, and shorts
Feel along the length of the power cord, bending and flexing as you go, to check for any kinks or breaks. Check the ends for any broken connections, such as a MagSafe connector pulling loose or spots that may have gotten chewed by a pet or caught in a vacuum cleaner. Inspect the AC brick. Is it discoloured? Are any parts warped or expanded? Give it a sniff – if it smells like burnt plastic, that's likely where the trouble lies.
4. Check the connector
The beauty of the MagSafe connector is that, unlike the average laptop power connector, the shallow magnetic port plugs in easily, with minimal play and few opportunities to damage the port. That is, in fact, what puts the "Safe" in MagSafe; the connector disconnects easily if someone pulls or trips over a cord, preventing internal damage. If, however, the port is damaged directly in some way – dropped on its corner, accidentally dinged with a hammer, whatever – it might be unable to connect. Is there any sort of damage to either the port or connector? There are two different MagSafe connectors on the market, with slightly different shapes. Does the port match the size and shape of the connector? If there is damage, repairs may be in order. If it's the wrong cable, it can be fixed with a simple swap.
5. Beat the heat
A non-charging battery can sometimes be caused by an overheating laptop. As the temperature rises, a thermal sensor shuts off the battery to prevent the lithium-ion polymer from becoming so hot it bursts into flames or explodes. While the unibody design used in the MacBook Pro and MacBook Air do a fairly good job of keeping everything cool, you might want to let the system cool down if it's warm to the touch.
6. Swap out cord and battery
Even if you can't find any damage on the power cable or battery (assuming it's accessible), swapping out one or both with a different cable and battery can quickly diagnose unseen problems you may have missed. If a simple swap fixes the problem, discard the offending item and simply get a new one. There are two different styles of MagSafe connector available, so be sure to purchase the one that fits your MacBook.
At this point we've eliminated the problems that can be caused by kinked cords or environmental issues. If you still find yourself powerless, the problem lies within the computer itself, caused by either a software issue or faulty hardware. Let's start by looking at the settings and software.
7. Check your settings
In System Preferences, select the Energy Saver pane and review your preferences. Mac settings are adjusted with a slider, letting you select the amount of time the computer can sit idle until it goes to sleep. If the interval is too short, you might suspect battery issues when settings are the true culprit. And don't forget to check these settings for both battery power and wall power. You may want to revert back to the default settings to see if a change in settings is causing the problem.
8. Update your drivers
On a Mac you'll need to try resetting the System Management Controller (SMC). For laptops with removable batteries this is as simple as shutting down the power, removing the battery, disconnecting power, and pressing the power button for 5 seconds. Reinsert the battery, connect power, and fire up the laptop.
For newer Macs with batteries sealed into the chassis, shut down the computer, but leave the power adapter connected. With the power off, press and hold the power button while pressing the Shift-Control-Option keys on the left-hand side of the keyboard. Release the keys and power button simultaneously, then attempt to power on the laptop.
9. Call in outside assistance
If you haven't already, this is probably a good time to contact Apple, whether through the Apple Support page, with a phone call to Apple Care, or a visit to the Genius Bar. Your particular make and model of laptop will likely have its own unique issues, and a seasoned tech support operator will have seen all of them. He or she will likely walk you through many of the steps outlined above, but will also be aware of software and hardware issues specific to your configuration, such as what bits of hardware commonly fail.
When all of your options are exhausted – you've tried other power cables and batteries, you've checked and rechecked your settings, you've fixed any potential software problems – the problem is likely found inside the machine. Several internal parts can cause problems when they malfunction or fail. Common culprits include a faulty motherboard, wonky logic boards, damaged charging circuits, and malfunctioning battery sensors. A visit to your friendly neighbourhood Apple Store and a chat with a Genius will usually help you determine whether your MacBook needs to be sent in for repair.