It doesn’t matter whether you’re buying a new laptop power adapter to replace a defective charger, or because you want a spare; you want to make sure you get the right one. Purchasing an incompatible charger is not only a waste of money, it could damage your laptop, itself, or even cause a fire. In this article, we’ll get into the details of everything you need to understand about getting a new laptop charger.
To be clear, we’re talking about that thing that you plug into the wall and plug into your laptop, bringing it to. You may call it a “power adapter,” a “power adapter,” or simply a “charger.” Aliases also include “wall wart,” “power brick,” “AC/DC adapter,” “charging brick,” the awkward “battery recharger,” and our pet peeve, the arguably misleading term “power cord.” All these refer to the same thing. When plugged in on both ends, your charger powers your laptop and charges its battery.
INPUT vs OUTPUT
First off, let’s talk about those numbers written on your charger. You’ll notice that your charger has specifications for both input and output. When it comes to the specs written on a charger, input refers to the voltage, frequency, and amperage that the adapter needs to be plugged into, while output refers to the power that it will supply. Charger input voltage needs to match the wall outlet voltage, while charger output specs should match your laptop’s input specs.
With this particular charger, it’s 100-240V, 50-60Hz 1.5A. Standard wall outlets in the Philippines supply 220V at 60Hz, although some houses are wired with 110V outlets as well. The 100V-240V range on the input voltage means this charger can and will work if plugged into any voltage within that range, so it should work with any Philippine socket.
You can ignore the input specs on a charger for the most part, as most chargers will be compatible with basically any power outlet, provided you can plug it in. If the plug doesn’t match, you’ll have to use a plug adaptor or replace the power cord with one that matches your wall sockets.
All laptops require a specific voltage from their power adapter. A good way to understand voltage is to think of electricity as water. If your laptop could run on water, voltage would be the water pressure that your laptop needs. If your water pressure is too low, nothing works. On the other hand, if your water pressure is too high, your pipes burst, flooding your house and ruining your carpets.
Using a charger with a voltage that is too low may not have any effect. On the other hand, if you use a charger with a voltage that is too high, the excessive stress can degrade your laptop and its components, possibly shortening its lifespan. Severe overvoltage can burn out and destroy your laptop’s circuits or cause a fire.
Does voltage have to be exactly the same though? Will cranking the water pressure up one tiny bit automatically be enough to burst your pipes? Not necessarily. Some laptops may list multiple compatible voltages. For example, a laptop may list both 19V 4.74A and 18.5V 3.5A as compatible inputs. Most laptops have an integrated circuit that handles power, also called a power IC, that can handle minor fluctuations in voltage, possibly variations within +10% of the listed voltage. Using a 20V charger in the place of a 12V adapter is dangerous, but using a 19.5V charger in the place of a 19V charger is pretty safe.
Things to remember about voltage:
- Input voltage on your charger should match the wall outlet voltage
- Most modern laptop chargers can plug into anything between 100V and 240V
- Charger output voltage should match the laptop input voltage
Amperage is a measure of electrical current. To continue the water-powered laptop analogy, the current would be the strength of the water’s flow, hence the term. Amperage is the size of the hose. A wider hose can handle more water flowing through it per second, while a smaller hose can handle less.
Hose a little bigger than needed? Shouldn’t be a problem. Hose a hundred times too big? Very impractical, and may not even work.
So what does this mean for your equipment? The higher the output amperage on a charger, the more “water” it can push at a time. The higher the input amperage on your laptop is, the more “water” it needs per second to run.
When it comes to amperage, it’s best to think of listed amperage as a minimum requirement, not an exact spec. For example, if your laptop’s input specs list “19V 3.42A,” that means you need to use a 19-volt charger that is at least 3.42A. You could use a 3.42A charger, a 4.74A charger, or even a 9.5A charger. What you shouldn’t do is use a lower-rated power supply. That would be like using an undersized hose.
You might ask, is using a higher amperage safe? Won’t a higher amperage charger damage your laptop? To help put your mind at ease, you can forget about the water and hose analogy for a little bit and understand that when it comes to electricity, current is pulled, not pushed. Your laptop is smart enough to know not to hurt itself by pulling more current than it needs.
A laptop draws power from its power supply. The question is not whether the laptop can handle the charger’s capacity; this is irrelevant. The question is: can the power adapter provide the amps that the laptop is drawing? If the answer is yes, you shouldn’t have a problem. Simply using a bigger hose doesn’t mean that more water is going to flow. As long as the pressure (a.k.a. voltage) is correct, your laptop will simply draw the amount of current that it needs.
The amperage listed on a charger’s output means “I can provide up to this number of amps.” If voltage and pin are compatible, you can use a charger with any laptop that lists input amperage as equal or lower.
The amperage listed on a laptop’s input means “I need this number of amps.” Assuming voltage and pin are compatible, you can power it with any charger that meets that minimum, or is rated higher.
Watts are a unit of power. Some chargers may indicate how many watts they can provide, but for those that don’t you can easily compute with this formula:
Watts = Amps x Volts
Anyone familiar with amplifiers, an electric bill, or DeLoreans knows that more watts equal more energy. But a higher wattage rating on a charger doesn’t mean it will consume that much energy when used. A 90W charger, simultaneously charging and powering a laptop that lists 90W input, for example, can provide up to 90W of power if required, but with real-world use, you would rarely see the power usage spike to 90W.
Theoretically, you might be able to max out your laptop’s power usage. You could try running your laptop with 100% CPU and GPU usage, maximum screen brightness, and speakers blaring at maxi volume. For good measure you could do all that while simultaneously burning a DVD, charging devices through your USB ports, and streaming video over WiFi. With an exercise like this, you’d succeed in quickly draining your battery if you were running your laptop unplugged.
However, even then you probably wouldn’t max out your charger’s capacity. Laptops are designed with allowances in mind, and your system would probably crash or auto-throttle before you hit the limit. Your 90W adapter would probably get pretty hot, but that would be within normal operating temperatures.
Since we’ve established that a higher wattage capacity is better, why shouldn’t you just get the highest-rated charger available? That’s because higher wattage has its tradeoffs. These chargers are usually bigger, heavier, and possibly more expensive than lower-wattage chargers.
No need to fight above your weight class.
A higher wattage charger doesn’t mean higher energy consumption, but it can be bigger or inconvenient.
There is no room for negotiation when it comes to charging pin type. You need to have the same charging pin, or you won’t be able to plug in the charger.
Charging pins are usually spec’d with two numbers, referring to the outer diameter and the inner diameter. When in doubt, you can measure your old charger to make sure it matches a charger you’re planning on buying.
A 5.5mm*2.5mm bullet-type pin
A common myth is that if a charger pin fits, that means it’s compatible with the laptop. That’s not always the case. Chargers may have the same pin but different voltage or amperage ratings.
While some laptop brands may use charging pin types unique to their hardware, many laptops share the same input pin type. Several manufacturers use 19V and a 5.5mm*2.5mm pin; as long as amperage requirements are met, these chargers will usually work with laptops from other manufacturers without a hitch.
Some manufacturers include proprietary chips in their adapters that make using other brands difficult or impossible. If you have a choice, it’s always best to get a charger that matches your laptop.
Some power adapters are advertised as “universal.” Let’s be clear on this: there is no such thing as a universal laptop adapter. The myriad voltages, pin types, and amperage requirements that laptops use make it impossible to make a truly universal charger.
Okay, so you decided to skip the physics lessons and water analogies and want to get right to the point. No problem. Here’s the quick and dirty:
When it comes to a replacement charger for your laptop, make sure that the new one has:
- the same voltage
- amps equal to or higher than your laptop’s input amperage
- the same charging pin
Save your time and money by making sure you understand what power adapter you need before you buy one. Your laptop will thank you.