Introducing Power Supply with Charger

Power supplies (PSU) and battery chargers both switch AC power into DC power, but the way they manage to achieve the goal is different. A power supply takes the AC power input and turns it into a DC output at the desired voltage and supplies it to the system. On the other hand, a charger turns the AC power into DC and store it in battery cells so that the system can make use of it. 

Yet, it is still important to learn the difference between a PSU and a charger because some systems run on particular power devices to operate and the last thing you want to do is run your application with the wrong power unit. After reading this article, we hope you can walk away with a basic understanding of these units.  

What is a Power Supply?

A power supply takes the energy from the electricity grid and converts AC power into a proper voltage and format for a specific application. For example, the power supply draws the 120V alternating current and converts the power into a 5V direct current to run the device. Since the use of the power supply almost always involves the conversion of current from AC to DC, it is also called AC/DC power supply.

Choosing the right power supply for your system is crucial. Each power supply unit changes the power input into a particular voltage and amperage output. You can check the label on your power brick to see the format. The worst thing that happened may not only damage your device but also cause a labor safety issue. Click here if you want to learn more about AC/DC power supplies.

What is a Charger?

A charger, also a recharger, draws the power from a power source and turns it into a DC current so that the battery can store the power in battery cells. Although battery is considered one type of power source, it is not like the power grid and or a generator. The battery is not expected to supply stable power for very long. Rather, it is related to the battery’s capacity. After the battery runs out, it will need to be recharged, and that is when the battery charger comes into play. In the following paragraphs, the focus will be the construction and working principle of the battery charger as well as the types. We will also spend some time taking a glimpse at what a battery charger is and how it works.

One takeaway is that each type of battery charger, just like the power supply, is built for one specific battery only. The last thing you want to do is to hook it to the wrong type of battery. Using the wrong charger may damage the battery life and the charger itself. So what is the construction of the charger and how to look for when you pick the right charger for your device?

Battery Charger Construction

The battery charger has a similar construction as the power supply. It has a transformer, a rectifier, and a voltage regulator. The transformer steps down the high-voltage input power to a low-voltage output. For example, the standard power grid is either 120V or 240V while the electronic apparatus consumes the voltage ranging from 1V to 120V. The rectifier is responsible for converting the AC voltage into a DC voltage. The transformer and the rectifier combination turns the high-voltage AC power into DC power at the target voltage. The advanced battery charger comes with a program charging step in order to prolong battery life and maintain the reliability of the power system.

How does a battery Work?

Generally speaking, a battery takes the DC current and stores the power in the form of chemical energy. When a system demands power, the battery turns the chemical energy back into electrical energy to power the system. Batteries have a cathode and an anode, and the electrolyte that separates these two terminals. When the current (carrying electrons) flows from the cathode to the anode, it increases the chemical energy; this process is known as charging. When the current flows in the opposite direction, the chemical energy turns into electrical energy; this is the discharging process. You can take the battery charger as a type of power supply that works specifically to charge the battery.

What to Look for When Choosing a Battery Charger?

When choosing the battery charger, there are many criteria to pay attention to than simply identifying the battery type, including amperage, voltage, and capacity..etc. So how do these specs affect your application? Let’s take a look.


Most battery and power supply manufacturers recommend that a charger’s size is supposed to be approximately ten to twenty percent of the battery’s Ah (amp-hour) rating. You can find the battery’s Ah rating on the label. If it exceeds twenty percent of the battery’s maximum capacity, overcharging is likely to happen. Overcharging refers to the situation where a charger continues to supply power to a fully charged (to a specified voltage) battery. Although different types of batteries react to overcharging differently, it almost inevitably increases the temperature and damage life of batteries. 


Checking the voltage compatibility is a key when choosing the battery (and power supply, too). The charger’s output voltage should be 5~10% higher than your battery voltage. Too much excessive voltage overheats your battery, reduces the battery’s lifespan, and damages your device. In the worst-case scenario, the battery catches on fire. In reverse, using a charger with a lower output voltage may lead to a long charging period and sometimes reduce battery capacity eternally.

Final Words

Understanding the specification of power supply units and battery chargers and choosing these units properly is a real hassle to most of us. The important things we need to keep in mind are dimension, capacity, and compatibility. Once we know the input power from the power grid and our application, we can easily choose the right unit. Although sometimes people may choose the wrong type of power supply or charger, the design of our power supply has protections to prevent further damage.

Acro Engineering is a reliable power supply and battery charger manufacturer. Our PSUs and chargers are built extra robust in order to cope with the most demanding environment and requirements. The overcurrent protection and overvoltage protection are the standards already designed in our products. In addition to these protections, there are more features to Acro’s products. Contact us right now if you need any further assistance.