Since household electricity is AC supply, I always wondered if my laptop operated on AC as well or it somehow used DC supply. If it did run on DC, how does it convert? The electrical nuance always bugged me.
So, do laptops run on AC or DC? Laptops run on DC (Direct Current). The power adapter in the laptop charger converts the AC coming from the wall socket to DC and sends it to the laptop battery to store charge and power the laptop.
In other words, while laptop essentially runs on DC, the power adapter (AC adapter) in the charger helps us to connect laptop to an AC socket by converting the AC power source from the socket to DC.
Let’s deep dive into the mechanics of how power adapter helps in connecting AC power source to laptops – which run on DC.
Do Laptops Use AC or DC?
Laptops operate on DC (Direct Current).
However, they are made viable to plug in to an AC power source with the help of a power adapter (also called AC adapter) present in their battery charger.
Both laptop battery and laptop itself requires DC power to store charge and operate. If not for the AC adapter, the battery and laptop will not run at all and most likely, will get damaged.
Then why do few people say laptops run smoothly on AC?
When these people say AC, they are not referring to the current that laptop runs on, but rather the current coming from wall socket – which is usually AC.
However, what they completely miss out on is – to access AC from the wall socket and power the laptop, an AC adapter is incorporated in the battery charger. The AC from the wall socket these people refer to gets converted into DC by the adapter before it reaches the laptop battery or directly to the laptop itself.
It is a common misconception that when people say laptops do run on AC, they don’t mean the current powering up the laptop but rather the power source the laptop charger is plugged in – which usually happens to be AC. They completely is out the role that power adapter plays to convert this AC into DC to charge up the laptop.
Charging System: From Household Socket To Laptop Battery
When you plug in the laptop charger to a household socket, you are basically deriving power from the household socket to transfer it to the laptop.
There is one tiny problem though.
The household socket is an AC power source and your laptop requires DC to charge up.
That’s the exact reason why there are AC adapters in our battery chargers. This is not just for laptops, even smartphones have adapters in their chargers to convert AC into DC for them to charge up.
Once the power adapter produces a DC output, the current flows to the battery and charges it up.
The battery stores the charge and supplies to the laptop to run smoothly. In case, you have removed the battery from your laptop, the current is directly consumed by the laptop to operate.
How Do Power Adapters Convert AC to DC
Now, how do these power adapters (AC adapters) convert AC (alternating current) to DC (direct current)?
Typically, an AC adapter consist of three components.
- Transformer
- Rectifier
- Filter
A transformer converts a high voltage AC coming from the socket to the required voltage levels for the laptop to charge. A high voltage is converted to a low voltage current suitable for the laptop.
Next, the rectifier converts the AC into DC. The low voltage AC from the transformer is converted into DC here.
Lastly, the filter smoothens out the output current. The DC coming from the rectifier will be pulsating and requires smoothening out. And filter does that role to result in a low voltage direct current (DC) as the final output.
Is a Laptop Battery AC or DC?
Invariably, all laptop batteries function on DC – direct current.
Since laptops operate on DC, their batteries should operate on DC as well. Laptop battery receives the charge from battery charger and uses it power the laptop.
In case, the power adapter is not working or you try to charge the laptop battery with a direct AC power source (skipping the AC adapter in between), most likely, the laptop battery is going to get damaged and might even take down the laptop as well along with it.
Why Do Laptops Use DC instead of AC?
Now that we know laptops run on DC, the next question that pops is why cant they use AC? I mean, the household electricity is AC, why not use directly that right?
This is because the electronic components within the laptop – from transistors to processors, they all require DC for smooth functioning.
While AC is better for transmitting electricity over larger distances, using them in electronic gadgets creates lots of noise and complexity.
The binary signals which are easily generated in circuits using DC might get distorted if the power source is AC. To avoid unnecessary complications, laptops and almost all electronic gadgets use DC instead of AC.
Related Questions
Can your laptop run without a battery?
Laptops run without a battery as long as the laptop charger is plugged in to constantly derive electricity.
However, since there is no charge stored, if the plugged in charger disconnects or the power supply goes off, the laptop will shut down instantly.
Is household electricity AC or DC?
Household electricity is AC (alternating current).
Any device plugged into household sockets will receive AC power. If the device requires DC to operate, an AC adapter should be included to convert the household AC into DC.
That’s why, laptops and smartphones have a power adapter in their chargers.
Can I charge laptop with DC power source?
Laptops can be charged with a DC power source only if the voltage ratings of the laptop battery and the power source are matching.
For a 6-cell laptop battery, the voltage rating will typically be around 12V to 19V. Make sure the DC power source operate around the same rating.