While you’re working on your laptop or streaming content it’s pretty handy to connect your phone to it via USB and get it charging up.

But will plugging your phone into your laptop be good for either device and will it charge your phone effectively?

Can A Laptop Charge A Phone?

Yes, a laptop can charge a phone if you connect the phone to it via a USB cable.

Phone chargers are usually between 5v and 15v (sometimes more if they support fast charging).

Laptop USB ports are either 2.0 or 3.0 and rated at 5v, so they are compatible with most phones.

However, they output slightly less amperage than most regular phone chargers.

This means that your phone will charge just fine when plugged into a laptop – it will just charge slower than when charging with an adaptor plugged into a socket.

But if your laptop features USB 3.0 ports it will charge your phone faster.

Older USB 2.0 delivers around 0.5A while newer USB 3.0 can deliver about 0.9A.

In fact, USB 3.0 ports on a laptop can deliver up to 1.5A, provided that data is not set to sync when the phone is connected to your laptop.

A laptop supporting USB 3.0 will charge your phone faster and can also support the charging of more power-hungry devices.

When you connect your phone to a power source, it tries to determine what type of power source it is drawing power from and uses a control chip to control which charging protocol to use.

Your phone will still accept your laptop as a power source, even though it is delivering much less power than the adapter would.

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Does Charging Your Phone On Your Laptop Drain Your Laptop’s Battery Faster?

A laptop charging a phone

If your laptop is plugged into the mains then charging a phone via USB will not cycle current from the laptop’s battery.

The current will come from the laptop charger and will usually reduce the rate at which your laptop will charge back up.

However, if the phone is connected to the laptop while the laptop is not plugged in and running on battery, the power the phone is drawing will be coming from the laptop’s battery and this will drain it faster.

When your laptop isn’t plugged in and you are using it to charge your phone, it is essentially acting as a power bank.

For the health of your laptop’s battery, you should try to only charge your phone from your laptop when it’s connected to the mains.

Is It Bad To Use Your Laptop To Charge Your Phone?

Using your laptop to charge your phone will not negatively impact your laptop’s battery as long as it is plugged into the mains.

When your laptop is plugged into an outlet and charging your phone, it will be power drawn from the socket that will be charging your phone and not your laptop’s battery.

This may result in your laptop charging more slowly but it will not negatively impact your laptop’s battery.

However, if your laptop is not plugged in and you are using it to charge your phone, it will be your laptop’s battery that will be providing the power to charge your phone and this will take a bit more of a toll on your laptop battery, causing it to degrade slightly faster than it otherwise would.

To minimize wear on both your laptop and phone’s batteries, keep your laptop plugged in when using it to charge your phone and disconnect your phone from it before it reaches 100%.

And allow your phone to drop to at least 70% power before connecting it to your laptop again.