How MacBook Batteries Degrade
MacBook batteries are lithium-polymer cells with a rated cycle life. Apple designs them to retain 80% of their original capacity at 1,000 charge cycles — that’s for all MacBooks sold since approximately 2010.
A cycle is not the same as a charge. If you use 50% of your battery today and top it back up, then use 50% again tomorrow and charge it again, that counts as one cycle, not two. Heavy users who drain and charge daily will hit 1,000 cycles in two to three years. Light users might take five years or more.
The problem isn’t that batteries suddenly fail at 1,000 cycles — it’s that capacity loss accelerates after that point. A battery at 70% original capacity holds noticeably less charge, but a battery at 50% capacity is essentially unusable for anyone working away from a power socket for more than an hour.
How to Check Your MacBook Battery Health
The built-in battery report
On any MacBook running macOS Catalina (10.15) or later:
- Hold Option and click the battery icon in the menu bar
- You’ll see one of: Normal, Replace Soon, Replace Now, or Service Battery
“Normal” means the battery is within acceptable parameters. “Replace Soon” means capacity is declining but the Mac is usable. “Replace Now” means capacity has dropped significantly. “Service Battery” can indicate a fault beyond normal wear — including a swollen battery.
The detailed view
For more specific data:
- Hold Option and click the Apple menu → System Information
- In the sidebar, under Hardware, click Power
- Look for: Cycle Count, Condition, and Maximum Capacity
Maximum Capacity is expressed as a percentage of the original design capacity. A reading of 82% means the battery holds 82% of what it did when new. Below 80% is where you’ll notice meaningful runtime reduction. Below 60%, most users find the MacBook genuinely inconvenient to use untethered.
What Replacement Costs
Battery replacement cost varies by model:
- MacBook Air (M1, M2, M3): £100–£150
- MacBook Air (Intel, 2018–2020): £90–£140
- MacBook Air (older Intel, 2012–2017): £80–£120
- MacBook Pro 13-inch (Intel): £100–£160
- MacBook Pro 14/16-inch (M1 Pro/Max, M2 Pro/Max): £140–£200
- MacBook Pro 15/16-inch (Intel): £120–£180
These are workshop prices for quality replacement cells with professional fitting. Apple’s own out-of-warranty battery service costs more.
The labour element of battery replacement varies by model. On older MacBook Airs and Pros, the battery is adhesive-mounted but accessible. On newer models, particularly Apple Silicon MacBooks, access requires more disassembly. On the 16-inch MacBook Pro (2019–onwards), battery replacement is one of the more involved jobs due to the casing design.
When Replacement Is Clearly Worth It
The Mac is otherwise in good condition and you want to keep it. If the logic board, screen, and keyboard are all fine, and the only issue is battery life, a replacement battery is almost always worth doing. A £100–£150 battery service extends useful life by several years on a machine that may have cost £1,000+.
You rely on the Mac for portable work. A machine that needs to be plugged in constantly isn’t a portable computer any more. If you regularly work away from a desk, battery replacement is a functional necessity, not a cosmetic upgrade.
The battery is swollen. A swollen battery is not a “needs replacing soon” situation — it’s a safety issue. Lithium-polymer batteries expand when they fail chemically. A swollen battery can push against the trackpad, bow the casing, and in rare cases become a fire risk. Replace it promptly.
The cycle count is under 800 but capacity is already below 80%. This indicates premature battery degradation — sometimes caused by heat, sometimes a faulty cell. Replacement makes sense because the battery has failed early, not just worn out.
When It May Not Be Worth It
The Mac has other significant faults. If the logic board needs work, the screen is cracked, or the keyboard is failing, stacking a battery replacement on top of multiple repairs may exceed the machine’s residual value. We’ll always give you an honest assessment — if the repair bill doesn’t make economic sense, we’ll say so.
The Mac is already very old and unsupported. macOS support for older Intel Macs has narrowed. A MacBook Pro from 2014 that Apple no longer supports in the current macOS will still run, but increasingly won’t receive security updates and will be incompatible with more software over time. Whether to invest in a battery depends on how much you need the machine and for how long.
You’re planning to replace the Mac within 12 months anyway. A battery replacement extends useful life, but if you’re already planning an upgrade soon, the economics change. In this case, the answer depends on how much the current battery limitation is affecting your work right now.
Apple Silicon Battery Considerations
On M-series MacBooks (M1, M2, M3), battery life is significantly better than Intel equivalents to begin with — Apple quotes 15–18 hours of typical use on M-series MacBook Airs. This means that even at 80% capacity, an M1 MacBook Air still delivers 12–14 hours of real-world use, which is more than most Intel MacBooks managed when new.
The implication: the battery in an Apple Silicon MacBook needs to degrade further before it becomes a practical problem. Don’t rush a battery replacement on an M-series Mac unless capacity has dropped below 70–75% or you’re seeing a “Service Battery” warning.
The replacement process on Apple Silicon MacBooks is more involved than older Intel models, so factor this into the cost comparison.
What We Do
Our Putney workshop handles MacBook repair including battery replacement for all models. We check the battery condition as part of any Mac diagnostic — if you bring a Mac in for any reason, we’ll flag battery condition if it warrants attention.
If you want a battery assessment before committing to replacement, we can check cycle count, maximum capacity, and the physical condition of the cell (looking for any early swelling) and give you a straight recommendation.
Call 020 7610 0500 or contact us to book a battery check or replacement at our Putney workshop.