What Was Happening
The HP arrived from a Mortlake SW14 owner having lost the one thing that makes a laptop a laptop: the ability to work away from a plug socket. It ran perfectly well on the mains, but the moment the charger came out, it died instantly — no warning, no few minutes of grace, just off. In effect it had become a very awkward desktop, tethered to the nearest socket. They asked us to diagnose it and quote.
It’s a fault that creeps up on people. The battery fades gradually over years, the “unplugged” time shrinks from hours to minutes to nothing, and one day the laptop simply won’t run without the charger. By then the cause is rarely in doubt — but it’s still worth confirming rather than assuming.
Our Diagnosis
- Recognised the classic pattern. “Works on mains, dies when unplugged” is about as clear-cut as laptop symptoms get. It means the machine itself is fine — it runs happily on mains power — but the battery is no longer storing any usable charge to run on when the mains is removed.
- Confirmed it was the battery, not the charging system. We checked that the machine was charging and running normally on mains, which tells us the charging circuitry and power jack are doing their job. That isolates the fault cleanly to the battery itself, rather than something feeding it.
- Confirmed end-of-life, not a deeper fault. A battery that holds nothing after a few years is simply worn out — the expected end of its life, not a defect elsewhere. That made the fix a straightforward replacement.
How We Fixed It
- Fitted a new battery. We replaced the exhausted battery with a new one, restoring the laptop’s ability to store charge and run unplugged.
- Tested it off the mains. The real proof of a battery replacement is unplugging it, so we confirmed the machine ran and held its charge away from the socket before it went back.
- Left it portable again. With a healthy battery in place, the HP went back to being a proper laptop — usable on the sofa, on a train, or anywhere without a plug.
The Result
The HP went home to Mortlake portable again, holding charge and running unplugged as a laptop should. A machine that had been quietly demoted to a desk-bound, mains-only computer was fully restored for the cost of a single consumable part — no new laptop required, and no fuss.
Why This Happens
Every laptop battery has a finite life, measured not in years but in charge cycles — each full charge-and-discharge uses a little of its capacity. Over time it holds less and less, so the unplugged runtime steadily shrinks, until eventually the battery can’t hold enough to run the machine at all and the laptop dies the instant the charger is removed. This isn’t a fault in the usual sense; it’s the normal, expected wearing-out of a consumable part, like tyres on a car. Every laptop will reach this point if you keep it long enough.
The good news is how simple the remedy is. On most laptops a battery is a designed-to-be-replaced part, and swapping it is quick and affordable — a fraction of the cost of a new machine, and it makes an otherwise perfectly good laptop feel new again. It’s one of the most satisfying repairs we do precisely because it’s so disproportionate: a small, cheap part restoring the whole point of owning a laptop.
The one piece of advice worth giving is on quality. Replacement batteries vary, and the very cheapest ones are a false economy — they often hold less charge than they claim, age quickly, and leave you back in the same position within a year. A good-quality battery, properly matched to the machine, holds its charge and lasts, which is why it’s worth the small difference over the bargain-bin option. Choose well and a new battery buys an old laptop years of portable life.
Local Help in Mortlake SW14
If your laptop only works plugged in and dies the moment you unplug it, that’s almost certainly a worn-out battery — and it’s a quick, affordable fix that makes the machine properly portable again, rather than a reason to replace it.
We replace laptop batteries from our Putney workshop, just along the way from Mortlake SW14, and we fit quality batteries that hold their charge rather than the cheapest that won’t.
Call 020 7610 0500, drop in to SW15, or use the contact form.