Is it Safe to Keep a Charger Plugged In All the Time?

[Un article de The Conversation écrit par Glen Farivar – Lecturer in Power Electronics, The University of Melbourne]

There may be a connected phone charger next to your bed, you never bother to unplug it when you don't use it. And another, laptop, near your desk?

But is it risky? Are there hidden costs linked to the permanent trendy chargers?

What does a charger contain?

Of course, all the chargers are different. Depending on their application and the required power, their internal structure can vary and be very simple … or very complex.

However, a conventional charger receives the alternating current (AC) of the wall outlet and converts it into a low -voltage DC), which is suitable for the battery of your device.

To understand the difference between direct and alternative current, you must consider the flow of electrons in a wire. In a DC circuit, the electrons move in a single direction and continue to turn in the circuit. In an alternative current circuit, the electrons do not circulate and move successively in one direction and then in the other.

The reason why we use the two types of current dates back to the time when Thomas Edison inventors and Nicola Tesla debated what type of current would become the standard. Ultimatelynone really had the upper hand, and today we are still stuck between the two. Electricity is traditionally generated in the form of alternating current (when using alternating coils), but modern devices and batteries require a direct current. This is why almost all electrical devices are equipped with an AC-DC converter.

To convert the alternating current into direct current, a charger needs several electrical components: a transformer, a circuit to carry out the proper conversion, filtering elements to improve the quality of the continuous output voltage, and a control circuit for regulation and protection.

Chargers consume energy even when they don't charge anything

The “vampire energy”, or “ghost energy” – the term used by Quebecers to designate the energy consumed by a charger that remains connected without being used – is very real.

If you leave it connected, a charger will continually consume a small amount of energy. Part of this energy is used to operate the control and protection circuits, while the rest is lost in the form of heat.

If we consider a small individual charger, vampire energy – also known as the monitoring energy – is negligible. However, if you add the consumption of the chargers of all home devices, waste of energy can become significant over time. In addition, the watch energy is not the prerogative of the chargers: other electronic devices, such as televisions, also consume a little energy when they are on standby.

Depending on the number of devices left connected, this can represent several kilowatt hours for a year.

That said, modern chargers are designed to minimize vampire energy consumption, with intelligent energy management components, which keep them in standby until an external device tries to pull energy.

The other risks of the chargers left connected

The chargers wear out over time when crossed by an electric current, especially when the voltage of the electrical network temporarily exceeds its nominal value. The electrical network is a chaotic environment and various increases in tension occur from time to time.

Exposing a charger to this type of event can shorten its lifespan. If this is not really a problem for modern devices, thanks to improvements on their design and control, it is particularly worrying for inexpensive and not certified chargers. These often do not present the levels of protection appropriate to overvoltages, and can constitute a risk of fire.

How should I treat my chargers?

Although modern chargers are generally very safe and they consume only a minimum of vampire energy, there is no need to unplug them anyway – when it is practical.

On the other hand, if a charger heats up more than usual, makes noise, or is damaged in one way or another, it is time to replace it. And you should not leave it connected.