Research Hub > How to Choose the Right AC Adapter for Your Device

November 09, 2022

Use Case
9 min

How to Choose the Right AC Adapter for Your Device

Learn how to choose the right AC adapter for your device.

CDW Expert CDW Expert
What's Inside

What is an AC Adapter?

An AC adapter is an external power supply that converts alternating current (AC) from a wall outlet to a direct current (DC) needed by an electronic device. Therefore, it is an AC/DC converter. When it supplies power to a battery-powered device, it is also accurate to describe it as a charger. Before picking the right AC adapter for your device, it is useful to know the reasons most portable electronics use external power adapters.

Installing the power components of devices in external AC adapters allows manufacturers to make them smaller. Those researching how to choose the right AC adapter should know that devices with external power adapters are lighter than those with integrated AC adapters. Having a separate and external AC/DC power adapter also reduces the heat produced inside an electronic device. This design also reduces electrical noise and improves safety.

A manufacturer can also support a wide voltage range by choosing an external power supply when designing the right AC adapter for your device. Lastly, external power adapters are easier to replace. Users do not have to throw away their devices if voltage spikes, or in the case of brownouts or electrical fires destroy their external power supply units.

Check Electrical Ratings to Choose the Right AC Adapter for Your Device

Before trying to find a matching AC adapter for a device, check if the OEM (original equipment manufacturer) adapter is available. Device manufacturers sometimes offer replacement chargers/adapters for their products. Determining how to choose the right power adapter for a device becomes easy if this OEM accessory is available. Find the specific adapter for the device by searching for it using the model number printed on the adapter shipped with the device.

In some cases, OEM adapters are no longer available from manufacturers. Therefore, finding the right AC adapter for your electronics requires selecting a compatible third-party accessory. The first step is to determine the electrical rating of the device.

When learning how to choose an AC adapter, it is also necessary to understand power adapter specifications. Manufacturers usually print such information on the labels of these power accessories. Alternatively, check the device’s user manual for the electrical ratings of its AC adapter. The most important sections to read on a power adapter label are voltage and current. However, polarity is also an important factor.

The unit for voltage is volt (V), while current ratings end in amps or ampere (A). Power adapters have AC inputs and DC outputs. Depending on the region, AC input can be 110/120V or 220/240V. To make it easier for users to choose an AC adapter, manufacturers usually offer adapters that support both voltages. Dual voltage adapters have listed input AC voltage ranges of 110 - 220VAC or 100 - 240VAC. These are most useful for travelers researching how to choose the right power adapter that will work in other parts of the world. The DC voltage (VDC) of the power accessory is as important as its AC voltage (VAC). When reading an adapter label, the VDC will be under the DC symbol. 

The AC symbol is a wave, while the DC symbol is a solid dash with three short dashes underneath it. The DC voltage is the output voltage of the adapter, and it is usually much lower than the input AC voltage.

Select an AC Adapter and Device with Matching Specs

The right AC adapter for your device is one with matching electrical ratings. The device’s input voltage and current must match the adapter’s output voltage and current. Check the device’s product label or user manual to see its rated voltage and current. Shoppers learning how to choose AC adapter should know that most power adapters have output DC voltages below 20V while their input AC voltages are over 100V.

Choosing an adapter with a higher or lower voltage or current rating may cause the connected device to malfunction. This happens if the adapter’s VDC is lower than the device’s input voltage even when their current ratings are the same. Using an adapter with a higher voltage will cause the connected device to detect an overvoltage. An AC adapter supplying electricity at a higher voltage than required will cause the connected device to run hotter. Sending power at a higher voltage will also shorten the lifespan of the device and may fry its internal circuits. 

Using an AC adapter with a different current rating can be an issue. When considering how to choose an AC adapter, avoid picking one that delivers a lower current than required by the device. Even when both the adapter and the device have the same voltage rating, the device will attempt to draw more current than the AC adapter can manage. This can cause the adapter to overheat. The device may fail to power on or struggle to stay on. If the current is too low, the electronic device may stay on, but its battery will not charge. 

It may surprise you that you can use adapters with higher current ratings than your devices. This recommendation holds true, as long as both devices have the same voltage rating. For example, a 10V/8A adapter can safely power a 10V/5A device. 

The last thing to consider when researching how to choose the right power adapter is polarity. The polarity of the AC adapter’s connector must match that of the power input or charging port on the device. There are two types of connector polarities: center positive and center negative. It is worth noting in an AC adapter buying guide that most power adapters use center-positive connectors.

A center-positive connector in the AC adapter has a tip that has a positive polarity. Its barrel or ring has negative polarity. A center negative connector has the opposite arrangement. It is essential to differentiate the symbols for both types of connectors when learning how to choose the right AC adapter for your device. Manufacturers may denote polarity by putting + (positive) and - (negative) signs in front of voltage ratings. Alternatively, they may represent polarity with diagrams. When researching how to choose an AC adapter, remember that a polarity diagram of the adopter features a circle on both sides. A center-positive adapter polarity has a line extending from a positive circle to the open-end circle. 

It's also important to find a power adapter with a connector that fits into the input power port of the connected device. If the connector is too wide, it will not slide into the power port, and if it's too narrow, it will form a loose fit and may fall out during use.

To choose the right AC adapter for your device, find one with voltage and current ratings that match those of the device. Durable monitor cables are convenient for visual artists who need proper video display, and the cable is a part of the equation. Do not forget to also consider the polarity and size of the adapter’s connector as they must be compatible with the device’s power input port. A quick read of this AC adapter buying guide will help you choose the right AC unit from the selection of AC/DC external power adapters.