How to find the right ac adapter or charger for your laptop

Tuesday, 17 April 2012 | Admin

Why has the adapter stopped working?

The ac adapter (also known as the charger or power supply unit/psu) regulates the current of electricity which flows to the laptop. It may stop working for a variety of reasons - including internal wiring that has come loose with age.

Obtaining the information required to find the right adapter.

Voltage and amperage.

To find an adapter suitable for your laptop, you need to know the voltage and amperage (ie the electrical power) required by your model. (Note: voltage is also known as volts and shortened to a ‘V’ symbol and the amperage is also known as amps and shortened to an ‘A’ symbol).

This information is generally located underneath the laptop, though sometimes - notably on some models of HP laptops - it is also found underneath the battery in the battery compartment. It may also be found, of course, on your old adapter, if you still have it.

Examples of the voltage are: 18.5v, 19v, 20v etc. Examples of the amperage will be 3.5a, 3.25a, 3.42a, 4.5a, 4.74a, 4.9a, etc

Wattage.

Some laptops – or the old adapters that come with them may only have the wattage information on them. (Note: wattage is also known as watts and often shortened to a ‘W’ symbol). For example, the laptop or old adapter may say 65W or 90W.

The wattage roughly equals the voltage multiplied by the amperage. For example 18.5v x 3.5a = 64.75w - rounded up to 65w (65 watts) or, for example, 18.5v x 4.9a = 90.65w - rounded up to 90w (90 watts).

Important.

You do need to know at least the voltage required by your laptop AND the voltage of the new adapter must fall within a plus or minus 5% range of your laptop's requirements. This is to avoid damage to your laptop. (Please see point a) under the 'Checklist' paragraph below for further details about this).

Matching the amperage is less important because as long as the new adapter's amperage matches or exceeds (by no more than double) the amperage of the old adapter it should be fine to use. This is because the laptop will only draw as much power as it needs. For example, replacing a 19V 3.42A adapter with a 19V 4.74A one should be fine. In this example, an adapter giving only 3.16A would not be suitable (the amperage would be lower than the previous adapter) neither would one providing 7.9A (more than double the amperage of the previous adapter).

Connector sizes.

It is also essential that the connector that plugs into the laptop is the right size. Laptop manufacturers tend to standardize on tip sizes, which tend to be based on adapter's power. For example, Acer connector tip sizes for their 65W adapters tend to be 5.5mm x 1.7mm and for their 90W adapters the tip size tends to be 2.5mm x 5.5mm.

If it doubt as to the tip size for your adapter model, check with the company selling the adapter. Adapters sold on our website are guaranteed to fit the model of laptop described on the page – you do not need go guess the connector size when buying adapters from us. (See picture to the right with an example of a connector tip and its size).

Checklist.

An adapter is suitable if:

a) the voltage is within plus or minus (+/-) 5% of your laptop's requirements.
For example if your old adapter (or the information underneath of your laptop) says 19V then an adapter that provides 18.5V or 20V, as well as another 19V charger is suitable for it.
Do not use a adapter which does not fall within the 5% range to prevent damage to your machine.
b) the amperage is the same or higher than your old adapter. For example, if your old adapter supplied 3.25A, then you can use a adapter which is 3.42A, 4.74A etc, - *as long as* the conditions in point a) (above) are met. Note - the amperage cannot be lower than what the laptop needs.
c) the connector size fits your laptop model.

All three of the above conditions must be met.

Things to note.

A note of caution; it is advisable to buy from a supplier within your country so that you may invoke any warranty given if necessary.

Also when buying, look for features such as "Over Voltage Protection", "Short Circuit Protection" and "Over Current Protection" which protects your laptop from suffering over heating or otherwise being caused damage by the adapter. Be especially wary about buying Far East imports cheaply from auction sites for the reasons given. For safety reasons the adapter should have CE and RoHS certification.

Finally.

To recap: if you your adapter is faulty, but your unit is under warranty, contact the manufacturer for a free replacement in the first instance. If it's outside of its warranty and your laptop is aging (or you don't want to pay the price of the branded retail model) use the advice given go buy a suitable generic replacement.

This article was supplied by Readycharged - suppliers of an extensive range of laptop adapters, chargers and power supply units/psu. To purchase from our range, please visit www.readycharged.co.uk

Share this article: