Battery swelling explained

A swollen battery is a physical fault, not merely poor battery life. Stop using and charging the MacBook, do not press the case back into shape, and arrange professional assessment.

Lithium-ion batteries contain layers of material designed to store energy in a very small space. As a battery ages or becomes damaged, chemical reactions can create gas inside its sealed pouch. The battery expands because that gas has nowhere to go.

Signs of a swollen MacBook battery

The trackpad is difficult to click or sits higher than normal.
The bottom case bulges or no longer sits flat.
The lid does not close evenly.
The keyboard or palm rest appears distorted.
The MacBook rocks on a flat table.
A gap has appeared between parts of the case.

These symptoms can have other causes, but they deserve prompt inspection. A battery can swell even if macOS does not display a service warning.

What to do now: shut the MacBook down if you can do so normally. Unplug the charger. Place it on a hard, non-flammable surface away from heat and anything combustible, and arrange professional advice. If it is hot, smoking, hissing or giving off an unusual smell, move away and contact the emergency services.

What not to do

Do not puncture, bend, squeeze or flatten the battery.
Do not keep charging it “just to get the files off”.
Do not carry it loosely in a crowded bag.
Do not put it in household rubbish or normal recycling.
Do not follow a casual online repair video unless you are properly trained and equipped.

The pressure can damage the trackpad, keyboard and case. More importantly, a damaged lithium-ion cell can release heat or catch fire. This is not a reason to panic; it is a reason not to improvise.

Does it mean the MacBook is finished?

Not necessarily. If swelling is found early and the rest of the Mac is healthy, battery replacement may restore normal use. The condition of the case, trackpad, connectors and charging system should also be checked because the expanding battery may have placed them under pressure.

“Service recommended” is not always swelling

Apple’s battery-health message can simply mean the battery holds less charge than it did when new. Physical swelling is different and should be treated more urgently. Apple advises contacting Apple or an Apple Authorised Service Provider when a battery is not functioning normally; independent repair is also an option, but safe parts, handling and disposal matter.

Can it be prevented?