What Is Ac Adapter For Laptop? Top Full Guide 2022

What Is Ac Adapter For Laptop? An AC adapter is a power supply that converts the alternating current (AC) from your home outlet to a direct current (DC). The benefits of using an AC adapter are convenience, versatility, and safety. It can be used with any device that has a plug-in connection.

We’re going to be showing you what an ac adapter is and why it is essential. The ac adapter powers your laptop while using it so that the battery doesn’t drain as quickly. This article by Medcpu will explain what ac adapters are, how they function, and why they are necessary when charging your laptop.

1. What are AC adapters for laptop?

If your laptop is running perfectly fine and then suddenly the battery gets to the point where it can’t power up your computer, you will have two options. If you are lucky and this happened within 15 months of buying it (or sometimes less time,) take it back for a replacement battery which should be covered under warranty until that period ends past its lifetime.

adapter for laptop

This means that if you are not the original owner of your computer or your laptop hasn’t completed more than 1 year since manufacturing, and there’s no way you could get a free replacement battery. But if none of these conditions above apply, you might want to pay $40-$100+ for a replacement part.

Here comes another option. A power adapter for a laptop is the part that connects from your laptop to the wall outlet. This provides additional current/voltage to keep running your laptop when the battery starts getting weak or dead.

2. What does AC stand for?

AC adapter stands for Alternating Current, and DC stands for Direct Current. All batteries are charged using Direct Current, which cannot power up desktop or laptop devices. We need to transform it into Alternating Current (in other words step up) to use it with our computer equipment.

You might have seen power adapters come with different output options such as 19V, 20V, 19.5V, 18V, etc., but most of them will work fine with any standard size plug if you only consider the voltage output. Do not mix up your power AC adapter with a transformer.

What does AC stand for?

A power adapter is NOT a transformer. Power adapters only change the current from Direct Current to Alternating Current, and they don’t have any way to increase or decrease AC voltage or current adapter. Transformers are pretty different from an ac adapter; transformers will also allow you to step down voltage and convert it into lower-voltage AC current (such as 120V in North America to 100V or 110V in Japan).

Still, they can NOT be used to increase/step up voltage like an ac adapter. If you want more technical details about power adapters and their conversion between DC and AC, please consult Wikipedia for detailed information.

There are two main types of power adapters: one which comes with surge protection and one without it. The reason why you might need to buy a power adapter with surge protection is so that you can protect your computer from voltage spikes created by lightning or power surges. It won’t do any good if the power adapter dies after safeguard your equipment from potential fire danger, right?

A typical laptop will use anything from 15 Watts to over 90 watts of AC adapter when plugged in at 100% battery capacity. If you don’t need to worry about whether your ac adapter has enough amperage (depending on where you live) or buying a new/replacement one after using it for 2 years, get an ac adapter with more wattage output than what’s recommended for your manufacturer’s specifications.

For example, suppose your laptop manufacturer recommends a 65W power AC adapter to work with their computer. In that case, you might need to buy an ac adapter with 70-80W if you find yourself using it more than the average person.

In summary: AC/DC stands for Alternating Current/Direct Current. All batteries are charged using Direct Current, which cannot power up computers or other electronic devices. We need to transform it into Alternating Current (in other words step-up) to use it with our computer equipment. Yes, there is such thing as a step-down voltage transformer, but they have very limited applications.

3. How can I tell if my AC adapter for the laptop is damaged?

The easiest way to check whether there’s a case with your power supply unit or AC/DC converter is by turning on your laptop without the battery installed. Usually, it will show you an error message ” Plugged in, not charging” or “Power Problems”, and shut off after a few seconds. If there’s no case with your AC/DC converter, but with the BIOS settings of your computer, you’ll get a blank screen during boot (sometimes it just freezes). In this case, you should adjust power management options in BIOS first.

How can I tell if my AC adapter for the laptop is damaged?

AC adapter for laptop as safety device: The label on the Power supply unit (PSU) will tell you what voltage output is normal. Different brands use different labels to mark their products, but if we take Dell as an example, a typical label will look like this:

  • Rated output: 90 W
  • Input Voltage: 100-240Vac(50/60Hz)
  • Output Voltage: 19 V dc
  • Output Current: 4.74A Power Tip
  • Connector: 3 pins 1.7 mm connector

The output current must be within the range of 4.74A. If it’s too little or too much, it means that your power supply unit is damaged and needs replacement. You should do this if you feel the heat when you’re using your laptop for some time.

Read more: How To Cool Down Laptop? Top Full Guide 2021

4. How can I prolong the life of my AC adapter power supply for laptop?

Charging the battery fully before using AC adapter: Most modern laptops use a Lithium-ion battery which offers longer working hours than other types of batteries ( NiCd, NiMH). The quality of li-ion batteries depends on the number of charging cycles, not on time or usage.

A full charge will help your battery to work at its best for a long time. Otherwise, you can shorten the lifespan of the storm and damage it permanently. Many experts suggest that you use your laptop until it dies and then plugs in the DC/AC adapter for the laptop. I think this is a far-fetched argument because most people have many things to do with their laptops when they’re away from home or office ( write letters, make phone calls, take pictures, etc.).So it’s not reasonable to keep working for hours without recharging. There are two ways to handle this :

  • Use your computer while plugged into wall power and recharge it occasionally.
  • Using a single lithium battery is not many conveniences for laptop users.

External batteries are also available, but they’re a bit heavy to carry around, and the price can be high. If you’re in a rush to find the closest power outlet to charge your battery, take an external adapter with spare batteries that fit your laptop model.

You have several options: AA or AAA-sized NiMH/NiCD rechargeable cell; Lithium-ion (Li-ion) cell -the same type used by Dell, HP, IBM, etc.; Cylindrical cells such as those used in Sony’s InfoLithium series of notebook computer batteries.

These chargers are designed for a handle on the go (vehicle charging kits often include one), but some will work just as well at home, using the supplied AC adapter power supply. And if you need to carry around your laptop and several spare batteries, you may as well buy a charger that will charge up to 6 cells at once.

5. How to distinguish original from fake?

Sometimes they look so similar! That’s true, especially if we compare replicas with genuine products with high counterfeiting rates as China’s market is very active. But few methods can let us make sure what we have is not just a replica but an original adapter:

a) First of all, I would like to recommend that you need to read attentively information printed on the box before making any payment case because every manufacturer tends to mark their products by special codes such as UL/CCC/CE/ROHS, etc. so you will know whether it’s original or not if they have those codes on boxes;

b) Also, scrutinize the material of the connector as some replicas are made of inferior quality metals while original ones use high-quality materials such as gold, silver, and lead-free copper, which won’t risk your health;

c) Some counterfeiters add fake holograms or stickers onto their products’ packages to make them look natural, but I’m sure that original manufacturers would never do that case because it’s illegal. So if you find there is any suspicious pattern printed on the box (for instance, Barcode), refuse them right away. If something unusual happened happens with packaging (such as broken seal, missing box, etc.), again, you should be very cautious because it’s probably a fake one.

6. Power output and cable length

Output power (wattage) of ac adapters plays an essential role in deciding how much power will be supplied to your computer or notebook. It is said that the higher wattage would provide more energy, but I did not find any such law yet, so what I am going to tell is just my research on related information from different sources:

Typically, original ac adapters with an output power of around 30 watts are suitable for ultrabooks/tablets / Chromebooks. In comparison, those with 60 watts are suitable for standard laptops and gaming laptops where battery life should run longer. If there is no wattage indicated on the adapter’s specification, it is doubted whether it’s original or not that should be treated with caution.

If you are considering a higher wattage for the adapter, ask other questions such as “what kind of laptop does this adapter fit in?” and “does my power outlet have enough power to supply more energy for this adapter?” would be very helpful for your decision making.

One last thing: if the cable length falls out of normal range (such as 3 meters or 1 meter), then the measurement is probably made longer artificially by adding some materials onto it and might risk safety issues. So better check before buying: whether it is USB or AC adapter type; whether there are any abnormal parts added into the cable (like copper, aluminum foil, hollow metals, etc.). If so, don’t buy it.

7. Original or compatible?

If you are short of budget but want to find a cheap original product, here is my suggestion: go for substitutes instead. Compatible products work exactly like originals with the same quality and performance, which also follow standards and regulations on safety issues and environmental protection (especially RoHS compliant ones).

The only difference between these two types is that they are made by third parties who bought technology from the manufacturer itself or committed other methods such as reverse engineering to make it work again (sometimes they could replace original components with third-party parts).

The copies may look natural, but they were also made of poor quality. If you are using them for a long time, it will damage your computer and may even hurt you. I highly recommend NOT to buy such goods as using them for a short time will bring you no benefits but a waste of money, time, space, etc.

8. Test before buying!

Just because the product is sold in-store or online doesn’t mean it’s safe to buy without testing. If it’s too cheap or looks like the original one, then there might be a high chance that it is fake, so better check by yourself by following some simple procedures below:

a) Check performance (check whether output voltage and current are the same as marked)

b) Measure radiated electromagnetic fields (EMF)

c) Check materials used

d) Check the length of the cable carefully (if there are any abnormal parts added to it). If you can’t do them, I suggest buying from someone whose knowledge of products is excellent. But if you are going to test the product yourself, there is one case that could happen: what if it doesn’t work?

If this happens after testing and buying the product, please don’t blame manufacturers because your decision-making might be wrong when testing or purchasing.

Here is my suggestion for you: ask the shop assistant kindly to help you contact the manufacturer directly (if they have ways) or find information on the official website instantly. They will try their best to handle your case as quickly as possible. Because of the high competition among sellers, most shops would not renege on their sales. So don’t worry.


Can I use any AC adapter for my laptop?

An AC adapter converts higher voltage from an outlet into the correct amount for using a computer. As long as the adapter’s power wattage is suitable for each laptop, it will be used. You can share power cords.

Can I use a 19v charger for a 20v laptop?

You can use 20v for 19v if the current score of 20v remains equal or higher. However, this is only temporary. To ensure correct circuit entry, it is best to charge the battery first and disconnect the notebook or laptop. It is not recommended to run 20v for 19v straight.

Can I charge 19V laptop power supplies with a 12V charger?

No, you can’t charge your 12V AGM batteries directly with a 19V laptop power supply. A battery charger is required. A laptop power supply is not a battery charger. It is a fixed voltage SMPS power supply.

Does using fake charger damaged laptop?

There are many types of laptop chargers on the market, but not all chargers work well. Fake clones and chargers of unknown origin are all possible. Low-quality chargers can cause damage to your device or even an explosion.


It’s easy to find an ac adapter for the laptop if you know what they are, how they work, and where to buy them. With so many different laptops on the market, it can be tricky to understand which one will suit your needs best- that’s why we created this article! We hope you found our guide helpful in helping answer some of those questions about AC adapters for laptops. If not, please let us know below in the comments section!

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