Laptop Charger: Lower or Higher Wattage Bad?

Here’s everything about using a lower or higher wattage charger for your laptop:

Using a lower wattage charger might seem safe, but it can actually cause problems with your power supply.

You can also use a higher wattage charger for your laptop, but it has to meet other specs like voltage and polarity.

Keep your laptop safe by using the right charger.

If you want to learn all about using a lower or higher wattage charger for your laptop, then you’re in the right place.

Let’s get started!

Laptop Charger: Lower or Higher Wattage Bad? (All the Info)

What Does Wattage Means on a Charger?

The wattage of a charger indicates the amount of power draw it can match.

Watts are a measure of electric power, and you can calculate it by multiplying the amperage by the voltage of a circuit.

What Is the Voltage of a Charger?

Voltage measures the difference in electric potential between two points in a circuit.

If we were to compare electric current to water, the voltage would represent a difference in water pressure.

What Are Amps?

Amps or amperes are another rating you can find on your laptop charger.

This measure indicates the strength of an electric current.

What Is the Difference Between AC and DC Power?

AC power or Alternating Current changes is an electrical current that changes directions at regular intervals.

The change in direction creates a wave-like motion that allows electricity to travel farther.

The power outlets you can find in your home deliver AC power.

DC power or Direct Current flows in one constant direction.

DC power delivers a voltage that is more consistent, which is why small appliances convert AC power to DC power.

Your laptop battery delivers a steady flow of DC power to the different components of your laptop.

How Does a Computer Power Supply Work?

The power supply plugs into a wall outlet and receives 110 V or 220 V AC power. It converts it to DC power and reduces the voltage to 3.3, 5, or 12 V. 

The motherboard will then distribute power to the different components of your laptop, including the battery that will store electricity in the form of DC power.

What Do the Different Specs on a Computer Charger Mean?

You will find different specs on your computer charger.

There are input requirements that indicate what kind of current the charger needs to get.

The most common input requirement is AC 100 V-240 V, which corresponds to a standard power outlet.

The output specs indicate the kind of power the charger can send to your laptop.

This section of the label should tell you that the charger will output DC power, but it will also indicate the voltage, amperage, and wattage the charger delivers.

Can You Use a Different Charger with Your Laptop?

The first thing to check is the size of the charger plug.

Manufacturers use different sizes and designs, and a charger from a different brand might not work with your laptop. 

You should also check the polarity of the charger. There is a diagram on the label of your charger with two circles and a plus and minus sign. This diagram indicates the polarity of the outer and inner plug. 

Check the polarity of your old broken charger to make sure the new charger is compatible with your laptop.

If you have lost the old charger, try finding information about its polarity online before you try plugging the new charger in.

The voltage output has to match the requirements of your computer. You should find this information on a sticker located on the back of your laptop.

The voltage has to be equal or as close as possible to this requirement. Don’t plug in a charger with a significant difference in voltage output.

The amperage output should be equal or greater to your laptop’s requirements.

You can connect a charger that delivers more watts or amps than your computer needs since your laptop won’t draw more power than it needs.

Can I Use a Lower Wattage Charger for My Laptop?

While it might seem safe to do so, a lower wattage charger can actually cause problems with your power supply.

See below for more on the problems.

Can I Use a Higher Wattage Charger for my Laptop?

The answer is yes, but you need to make sure that the charger meets other requirements, including voltage and polarity.

Your laptop can only draw so much power, and it won’t exceed its power requirements if the charger can deliver a higher wattage.

Check the charger’s wattage or amperage output before connecting it to your laptop.

If you have more than one charger to choose from, look for the one with the output specs that match your laptop’s requirements as closely as possible.

Can I Use a Lower Amp Charger for my Laptop?

You can, but you will run into some limitations and could damage your laptop.

For instance, a laptop that requires 90 watts will get half the power it needs to run if you use a 45 watt charger.

Keep in mind that what you do on your laptop can cause power consumption to vary a lot.

A 90-watt laptop that is idle with a low screen brightness setting might stay on without any issues if you use a 45 watt charger.

If you launch an app or stream a video, your laptop will probably switch to battery power and shut down once the battery runs out.

You will likely have a hard time charging your battery with a charger that has a lower amperage output.

The battery might charge slowly, or the charger might not be able to deliver enough power to keep the computer running and charge the battery at the same time.

There are risks associated with using the wrong charger. If the amperage is too low, you could trip a fuse in the power supply and damage this component. 

Ruining your charger might not be a big deal if you have a spare, but an issue with your power supply can damage other components of your laptop.

Overall, it’s safer to avoid using a charger with a wattage or amperage output that is too low.

If you have more than one charger available, use one with a wattage output that is higher than your laptop’s requirements. 

Is Charging Laptop with Lower Voltage Possible?

Your motherboard has a component called a voltage regulator.

The purpose of this component is to adjust the voltage of the current your laptop receives to match the requirements of the different internal components.

The voltage regulator allows your laptop to operate within a certain voltage range. For instance, a 19 V charger can power a 20 V computer without any issues thanks to the voltage regulator.

However, a charger that delivers a voltage that is significantly higher or lower than the laptop’s requirement can cause the voltage regulator to fail.

You might be able to charge your battery and keep your laptop running with a lower voltage as long as the voltage regulator can keep up.

If you don’t have access to a charger with a voltage that matches your laptop, it’s best not to connect it to your computer since you could damage it. 

Can You Use a Charger with a Higher Voltage?

The answer is no. There is a strong possibility that a charger with a higher voltage will cause serious damage to your laptop.

Your laptop’s voltage regulator will more than likely fail or cause power spikes.

It’s best to avoid using a charger with the wrong voltage, and some manufacturers use different plug sizes for different voltage ratings, so you don’t damage your laptop accidentally with the wrong charger.

What Are the Signs a Laptop Isn’t Getting Enough Power?

Can I use a lower wattage charger for my laptop?

Your laptop might power on, but you will probably run into some issues. Here are some common signs that your computer isn’t getting enough power:

  • The most obvious sign is the laptop not powering on or switching to battery power even though you plugged the charger in. 
  • You might notice that the battery isn’t charging or is charging at a slow pace.
  • The GPU or graphics card is one of the components that uses the most power. If the charger isn’t delivering a sufficient wattage, you will see issues with graphics and your display. You might notice low-quality graphics on some games and apps and might get error messages about your GPU. 
  • Display problems are another common sign that your laptop isn’t getting enough power. You might see your display flash or notice dots and lines. The screen might completely shut off.
  • Your laptop will probably be unstable. Some programs might crash, and the laptop could freeze or shut down randomly.

If you notice any of these signs, it’s best to turn your laptop off and wait until you have the right charger before using it again.

You could cause some serious damage to your computer if you try to use it with the laptop not getting enough power.

Can the Wrong Charger Damage Your Computer?

The answer is yes.

You should know that there is a risk of damaging your laptop if you use a charger with a lower wattage rating.

The same thing is true if you use a charger with a different voltage rating.

The power supply or charger is likely the first element that will fail. It might not be an issue if you’re using an old charger, but a failing power supply can damage other components through power spikes and ruin your laptop.

When Is it Safe to Use a Different Charger?

Under no circumstances should you plug a charger with the wrong polarity or a significant difference in voltage.

You could damage the power supply, and the failing power supply could cause a wide range of issues with your laptop’s components.

A difference in amperage or wattage isn’t necessarily an issue.

If the charger delivers more amps or watts than your computer needs, you can still use it since your computer won’t draw more power than it needs. 

However, it would be best to use a charger with the correct output as soon as you can replace it.

Can I use a lower wattage charger for my laptop? You can try if you need your laptop for an emergency, but it’s not a safe option. 

Your system will probably be unstable, and you won’t be able to charge your battery.

There is also a risk of damaging the charger and, by extension, your computer.

How to Make the Most of Your Battery Charge?

If you don’t have access to your laptop charger, your best option is often to rely on your battery until you can get the right charger.

It’s best to try and make your battery last longer instead of plugging a charger that could damage your laptop.

The main problem with relying on your battery is that most batteries don’t last longer than 10 hours.

Most batteries last for 1,000 charges, and you will typically see a drop in performance as the battery ages.

There are a few things you can do to make your battery last longer:

  • Lower your screen’s brightness. You can add hours to your battery’s life with this simple trick.
  • If you don’t need to go online, enable airplane mode. Staying connected to a Wi-Fi network can drain your battery.
  • Your laptop’s Bluetooth feature can use a lot of power. Unpair any Bluetooth accessories.
  • Avoid launching apps, software, and games. These activities use more power.
  • Streaming videos can drain your battery faster. Wait until you can plug your laptop in to watch videos and use an ad blocker to prevent video ads from loading on the web pages you visit.
  • Look for apps and services that run in the background by opening the task manager. You can turn off things like your laptop’s backup service for now.
  • Turn off your desktop mailbox app. This service constantly connects to the internet to check for new messages. 
  • Disable apps with location-based services. These apps use your laptop’s built-in GPS feature, which requires power.
  • Unplug accessories, including your wired or wireless mouse and keyboard.
  • Most laptops have a power-saving mode. You can usually enable it by clicking on the battery icon in the bottom right corner of your screen.
  • Let your laptop go to sleep when you’re not using it.

If you don’t have access to the right charger, the best alternative is to use a portable power bank to charge your battery. 

It’s a convenient accessory for charging your laptop or phone on the go, and power banks can match a wide range of power output requirements to charge your battery safely.


  • Theresa McDonough

    Tech entrepreneur and founder of Tech Medic, who has become a prominent advocate for the Right to Repair movement. She has testified before the US Federal Trade Commission and been featured on CBS Sunday Morning, helping influence change within the tech industry.

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