Laptop batteries don't usually fail overnight. They give you plenty of warning first, if you know what to look for. Most people put up with a dying battery for months longer than they should, not realising a replacement costs less than a tank of diesel and takes under an hour to fit.
Here are the five signs your battery is on the way out, and what to do about each one.
It barely lasts an hour off the charger
A battery that used to last six hours and now struggles to hit one is a battery that's lost most of its capacity. All rechargeable batteries degrade with each charge cycle. After 500–800 cycles most laptop batteries are operating at 60–70% of their original capacity. On an older machine that can mean under an hour of real use.
It shuts down without warning at 20% or higher
This is the most frustrating symptom. The battery gauge says 25%, then the laptop dies without warning. What's happening is the battery can no longer hold the voltage it reports. The reading drops suddenly under load and the machine cuts out. It's not a software problem, and restarting won't fix it.
The laptop is hot all the time, even when doing nothing much
A degraded battery has higher internal resistance. That resistance generates heat. If your laptop is running noticeably warmer than it used to, especially around the bottom where the battery sits, the battery is working much harder than it should to do the same job. Heat also accelerates the degradation further, so it compounds over time.
Windows reports a battery health warning
Windows 10 and 11 both monitor battery health. If you see a red or orange battery icon with a warning message, or if your system tray shows "Consider replacing your battery", that's Windows confirming what you probably already suspected. You can generate a full battery report in Windows by opening a command prompt and running: powercfg /batteryreport
The base of the laptop is bulging or the trackpad is lifting
This one is urgent. A lithium battery that's swelling is a fire risk. If you notice the laptop base bowing outward, or the trackpad lifting up from the chassis, stop using the laptop immediately and don't charge it. Bring it in. A swollen battery needs to be removed safely. Don't try to do this yourself.
Is a replacement worth it?
In most cases, yes. A decent replacement battery for a typical laptop costs €30–€60 in parts. Labour at Fentech is around €40–€60. So an all-in cost of €70–€120 gives your machine years more life. Compare that to a new laptop at €600+.
The exception is if the machine is already very slow, has other hardware problems, or is so old that a fresh battery still won't make it usable. When you bring it in, I'll tell you straight whether it's worth replacing before charging you anything.
