A laptop that lasted all day when it was new and now needs the charger by lunch is not broken. Its battery has aged, which every battery does, and it may have aged faster than necessary. Some of that can be slowed, some can be recovered with settings, and when neither is enough, the battery can usually be replaced for far less than a new laptop.
Check the battery's health first
Both Windows and macOS can tell you how much capacity the battery has lost.
- Windows: search the Start menu for Command Prompt, and run
powercfg /batteryreport. It saves a report as a web page; open it and compare Design Capacity with Full Charge Capacity. A battery at 80 percent of its design capacity is normal after two or three years. Under 60 percent is worn out. - Mac: hold the Option key and click the battery icon in the menu bar, or look under System Settings, Battery, Battery Health. "Service Recommended" means it is time.
If the battery is healthy and the laptop still does not last, the problem is what the laptop is doing, and the settings below will help. If the battery is worn out, no setting will fix it.
Settings that make the biggest difference
- Screen brightness. The screen uses more power than anything else. Turning it down from full to comfortable can add an hour.
- The power mode. Windows has a power mode setting under System, Power; choose Best power efficiency on battery. Macs have Low Power Mode under Battery.
- What is running. A browser with many tabs, a video call, or a program you forgot about in the background all cost battery. Task Manager on Windows and Activity Monitor on a Mac show the Energy or Power column for a reason.
- Background apps and start-up items. The same trim that speeds up a slow computer improves battery life.
- Bluetooth and the keyboard backlight cost a little each. Turn them off when they are not needed.
- Heat. A hot laptop drains faster and ages its battery faster. Use it on a hard surface, not a bed or a cushion that blocks the vents.
Habits that slow the ageing
Batteries age fastest when kept at full charge and hot, and when they are run flat. For a laptop that lives on a desk plugged in, most makers now offer a setting that stops charging at about 80 percent; on Windows it is in the maker's own app, on a Mac it is Optimized Battery Charging. Turn it on. For a laptop that is carried, charge it when convenient and do not worry about it; modern batteries do not need to be run down before charging.
When to replace the battery
When the report shows the capacity well below 60 percent, when the laptop shuts down with charge still showing, or when the battery has swollen. A swollen battery pushes the trackpad or the bottom cover up, and it must be replaced at once and kept away from heat; it is a fire risk.
What a replacement costs and involves
- Laptops with a removable battery are rare now, but if there is a latch on the bottom, a replacement is a part you buy and click in.
- Most laptops have the battery inside, held with a few screws and a connector. Replacement is a routine repair that takes under an hour. Expect to pay for the part plus a modest labour charge. Our guide to what a laptop repair should cost gives ranges.
- Thin laptops and MacBooks have the battery glued in, and the job takes longer and costs more. Apple and the major makers offer fixed-price battery service; for a laptop worth keeping, it is good value.
Use a battery from the maker or a reputable supplier. The cheapest batteries online are a false economy and occasionally a hazard.
Is it worth doing?
If the laptop is otherwise fine and less than five or six years old, yes; a new battery makes it feel new for a fraction of the price. If the laptop is also slow, cannot run a supported version of its operating system, or has other faults, our guide to repair or replace helps decide, and the money may be better spent on a replacement.
If you would like it checked
We check the battery health, tune the settings and, if a new battery is the answer, fit one. Bring the laptop and the charger.