Laptop chargers and AC adaptors: how to tell one is failing and how to choose a replacement

Replace an AC adaptor when the laptop stops charging, charges on and off, or the brick or cable is damaged, hot or buzzing. A replacement must match three things: the connector tip, the output voltage, and a power rating in watts at least as high as the one your laptop came with.

Also called: AC adaptor, AC adapter, laptop charger, notebook charger, power adaptor, power supply, power brick, mains adaptor, PSU, USB-C charger

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What an AC adaptor does

The adaptor converts mains electricity into the low-voltage direct current the laptop runs on, and charges its battery at the same time. It is usually two pieces: a mains cable that plugs into the wall, and the brick with a fixed cable that ends in the tip. Laptops with USB-C charging take power through a USB-C cable instead of a barrel-shaped tip, and agree the voltage with the adaptor when it is plugged in.

How do you know the adaptor is failing?

  • The charging light on the laptop or the adaptor does not come on.
  • Charging starts and stops when the cable is moved, especially near the tip or the brick.
  • The laptop reports that a low-power or unrecognised adaptor is connected.
  • The battery drains even while plugged in, or the laptop runs slowly when plugged in.
  • The brick gets very hot, smells of burning, or makes a buzzing or whining sound.
  • The cable is cut, crushed, kinked or frayed, or the tip is loose or bent. Stop using a damaged adaptor.

Rule out the other causes

Try the adaptor in a different wall socket, and check the mains cable between the wall and the brick, which is a separate part and can fail on its own. If a known-good adaptor does not charge the laptop either, the fault may be the laptop's power socket, also called the DC jack, or its battery, not the adaptor.

How to choose the right adaptor

  • Read the label on your old brick. It shows the output voltage, the current in amps, and often the power in watts, as well as the manufacturer's part number.
  • Match the output voltage exactly.
  • Choose a power rating in watts equal to or higher than the original. A higher rating is safe, because the laptop draws only what it needs. A lower rating may charge slowly, not at all, or trigger a warning.
  • Match the tip. Tips differ in outer diameter, inner diameter and length, and many laptops use a centre pin that lets them identify the adaptor. Two tips can look alike and still not fit or not charge.
  • For USB-C laptops, choose a USB-C adaptor, often marked USB PD, that supplies at least the power your laptop needs.
  • If there is no label, use the laptop's exact model number from the label underneath it. The input voltage and power the laptop needs are often printed near the power socket.
  • Check whether the adaptor comes with a mains cable. Many are sold without one, so you may need a cable with the right South African plug.

Looking after an adaptor

  • Do not wrap the cable tightly around the brick. Most cable faults start where the cable leaves the brick or the tip.
  • Keep the brick in the open while it is working, not under a pillow or inside a bag.
  • Unplug by the plug, not by pulling the cable.

Common questions

Can I use an adaptor with more watts than my old one?

Yes, as long as the voltage and the tip match. The laptop draws only the power it needs, so a higher-rated adaptor is safe to use.

Why does my laptop say the adaptor is not recognised?

Many laptops read an identifier through the tip's centre pin. A damaged cable or tip, an adaptor that is too weak, or one the laptop does not recognise can cause this message, and the laptop may then charge slowly or not at all.

Is a universal charger with several tips a good idea?

It can work, but the voltage, the tip and the identification must all suit your laptop. An adaptor made for your model avoids the guesswork.

Does the adaptor come with a mains cable?

Not always. Check the listing. The mains cable between the wall and the brick is a separate part, and the plug type has to suit the country it is plugged in.

Is a slim adaptor the same as the standard one with the thicker cable?

A slim and a standard adaptor with the same output voltage, power rating and tip do the same job. The slim version is smaller and lighter, and some have a thinner cable. Check the tip and the watts against your laptop, and either one will charge it in the same way.

Can I use a charger sold for a different laptop brand?

Only if the voltage, the tip and the power rating all match, and the laptop does not insist on identifying its own adaptor. Laptop makers identify their adaptors in different ways, so an adaptor that fits the socket can still be refused or charge slowly. Compare the label on your old adaptor with the listing.

Which adaptor does a laptop that charges by USB-C need?

One that supports the USB charging standard marked USB PD, and supplies at least the watts your laptop came with. A weaker USB-C adaptor may charge slowly, charge only while the laptop is asleep, or not charge at all. A phone charger is usually far too weak.

How do I find the right adaptor if I do not know its part number?

Use the laptop's exact model or product number from the label underneath it. The voltage and power the laptop needs are often printed near its power socket too. Send those with your request and we will match the adaptor's voltage, tip and watts.

Find your AC adaptor

Not sure which one you need? Send us the number from the label, or your machine's serial number, and we will confirm the match before you order. Ask us to find a part

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