Unplugging Laptop Charger from Wall to Save Energy

In modern (circa 2020) motherboards, a dedicated charger IC is utilized to control the power source between the AC wall power and the battery through a MOSFET. This approach is one of the many ways to implement this feature. Studies reveal that maintaining the battery level between 20% to 80% can significantly enhance battery life instead of charging from 0 to 100 or completely discharging it.


I wonder if leaving the charger on my desk all the time is harmful to it in the long run, even though it is more convenient for me to insert the battery as needed.

In the absence of the battery, there seems to be no activity and no heat generation. However, is it possible to encounter any harm or safety concerns that need to be taken into account?

While I understand that my inquiry may not be relevant to Photo.SE, I am particularly interested in this information for my Nikon D90 camera’s EN-EL3e battery and MH-18a charger. However, I believe it may also be valuable to other equipment owners.

Solution 1:

Leaving the battery plugged in is safe as long as it’s not in the charger. Although some chargers may have a small power drain when plugged in, it will not harm the device.

Solution 2:

Turning off the switch is recommended to conserve power, but it will not cause any damage to the charger.

Solution 3:

The power drain caused by
transformer circuit
may or may not harm your device, as there are several other factors involved. It is important to consider the flow of current as one of these factors.

Providing comprehensive technical information may pose some challenges in this context, nevertheless, I will attempt to clarify by including relevant links.

battery charger
typically comprises of a pair of elements.

  1. A transformer designed to reduce the voltage of a standard household power supply of 220/110V to a level that is suitable for electronic circuits.
  2. Provide an alternative current, referred to as
    DC converter
    , which can be utilized to charge the battery.

The transformer consists of two inductively coupled components. In an ideal scenario where the inductive coupling is 100%, no current should flow through the other end if one end of the circuit is open without a battery. However, in real-world scenarios, there is no load power that gets drained from the supply.

I regret not being able to provide further specifics, as the majority of the audience may not find it compelling. 🙂

Solution 4:

The lifespan of an electric component is finite, including the charger. Although current still flows and generates heat when the charger is plugged in without a battery, it is minimal when on standby. Consequently, while technically the charger is being harmed, practically, it is not. Inevitably, the charger will break down whether it is used or not.

Frequently Asked Questions

Posted in Uncategorized