Here’s why your laptop only charges to 80 percent:
This can happen because of deliberate design choices or because something is wrong.
As batteries and chargers age, they can lose capacity, and a problem with either could prevent the battery from exceeding an 80% charge.
Manufacturers deliberately stop charging at 80% to extend battery lifetimes.
So if you want to learn all about why your laptop never fully charges to 100 percent, then this article is for you.
Let’s jump right into it!
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Do Laptops Not Charging to 100% Really Happen?
Naturally, computers can have problems, and that can include laptop batteries.
So, surely, across all the laptops in the world, some only charge to 80%.
That’s not really the question we’re exploring right now.
Is this a common thing?
Are manufacturers limiting charging to 80%?
In most cases, it’s not a thing.
If you look at a bunch of different laptops, you’ll see that most can charge well above 80%.
Some might stop somewhere between 95 and 100%.
The reasons for that will be explained in the sections below.
But, stopping at 80% is less common.
For the most part, this is an ASUS feature.
ASUS has a tool that controls battery charging.
There are several different settings, and the “Balanced” setting will stop charging the battery when it gets to 80% full.
The reasons for this are covered in the pros and cons sections later, but the point is that this is done on purpose.
Other manufacturers might stop charging at different percentages, but overall, the concept is the same.
So, yes, this is a thing.
Why Does the Laptop Only Charge to 80%? (5 Reasons)
Even though laptops do stop charging at various percentages (including 80%), the reasons aren’t always the same.
There is a mix of deliberate and unintended interactions that can impact how a laptop battery charges.
I’m going to take you through all of the most common scenarios so that you can see the different forces at play.
When we’re done with that, I’ll explain the pros and cons of deliberately limiting battery charges so that you’ll understand why ASUS (and other companies) does this.
#1 Deliberate Charging Limits
ASUS has provided us with an easy example, but any manufacturer could limit how laptop batteries are charged.
That’s because smart charging is standard for laptops these days.
Smart charging means that there is a software controller that manages the charging process.
So, whenever there is a smart charging controller, the settings can be adjusted as desired.
ASUS can set the maximum charge to 80% or any other number, and any other manufacturers can do what they think is best too.
There are two things to understand about this.
First, smart charging is deliberate, and I’m actually rolling all of the different motivations into one idea.
In this case, we would say that your laptop only charges to 80% because the smart charging controller is set up that way.
Second, the primary motivation to do this is to extend the service life of the battery.
I’ll explain more about how and why this works later, but here’s the short version.
Charging a battery past 80% of its capacity puts more strain on it than only charging it to 80%.
That’s the gist.
#2 Display Errors
There’s a completely different possibility.
It might be that your battery actually is charged beyond 80%, but the display is only showing an 80% charge.
Again, this could just be a case where things aren’t working as intended, but this kind of thing is actually done on purpose sometimes.
Basically, there’s a margin of error in reading a battery’s charge.
Every battery is a little bit different, and over the course of its life, the actual charge capacity for any battery will change.
Because of these factors and others, when your laptop tells you how charged the battery is, you’re not getting a perfectly reliable number.
It’s really more of a best guess.
To deal with this, there are a lot of options, but something a manufacturer can do is just worry about charge ranges.
Instead of telling you exactly how charged the battery is, it only cares about being accurate to the nearest 5% or 10%.
So, you might read 80%, but really the battery is charged to 85% or even 80%.
You see this work in the other direction a lot of times.
There are batteries that will never say that they are 100% full, even though they’re pretty close to completely full.
It’s a rounding decision, rather than a real error, and it can make a battery say 80% even when that’s not really the case.
#3 Battery Wear
This idea isn’t exactly an error, but it’s not exactly on purpose either.
It’s kind of between the two ideas.
In essence, batteries wear down.
They are physical devices, and all physical devices eventually break.
More than that, batteries are chemical, consumable devices.
By the nature of how they work, using them shortens their lifespan.
It’s kind of like brakes on a car.
When you use your brakes to stop, you are grinding them to create friction and slow the vehicle.
That friction literally scrapes material off of the brake pads.
Stop enough times, and the brakes wear thin and stop working.
Batteries are similar.
Every time you use or charge a battery, it undergoes a chemical change.
Eventually, enough of the battery goes through that chemical change, and the battery loses functionality.
What does that have to do with 80%?
Well, unless the display is recalibrated as the battery wears down, the amount of charge the battery can hold will go down.
Basically, today’s 80% is yesterday’s 100%.
The old, worn battery is actually at its full capacity, but that capacity is only 80% of what the battery could hold when it was brand new.
There’s also a chance that the problem isn’t with the battery or the display or any controlling software.
Because of how electricity works, a battery charges more slowly as it gets fuller.
Let me give you a crash course on this.
When you charge a battery, you’re more or less filling it with electrons.
Every electron has a negative charge, and as you might remember, things with the same kind of charge repel each other.
So, when the battery is empty, there aren’t many negative charges inside of it, and you can pump electrons in there very easily.
But, as the battery fills up with negative charges, they push back against your attempts to pump even more electrons into the battery.
This relationship means that you have to use more electric force to keep adding electrons as the battery gets full.
The result of all of this is that filling the first 80% of the battery’s capacity often goes faster than filling that last 20%.
So, it might be that your battery isn’t full at 80%.
Instead, the rate of charge increase just slowed down a lot, so even though you checked it minutes apart, it didn’t go up from 80%.
Give it enough time, and you’ll see the number continue to rise.
This is more exaggerated when you get above 95% full, but it can happen at any point if you aren’t keeping careful track of how long the battery has been charging.
#5 Charger Current
The last issue is that the charger might not be able to push enough current to fill the battery beyond 80%.
Remember how it takes more power to top off the battery as it gets more full?
Well, not all chargers are equal, and some might not have the ability to fully charge your battery.
This is most common in two situations.
The first is with a third-party charger.
If you’re using a laptop charger that was not made specifically for your model, then it might have the wrong specs, and it might not be able to fully charge your battery.
The other common scenario is that you have a faulty charger.
Battery chargers can wear out over time.
In other cases, they leave the manufacturer’s warehouse defective.
In either case, they aren’t processing enough current to fully charge the battery, so you can’t get above 80% full.
Are There Pros and Cons to Only Charging to 80%? (2 Things)
We just covered all of the major reasons that your laptop will only charge to 80%.
Some of those reasons are deliberate design decisions.
Others are errors or accidents.
For this next part, we’re going to specifically discuss the pros and cons of deliberately limiting a laptop charge.
Accidents and mistakes don’t really fit in at this point.
If you think your laptop is only charging to 80% because something is broken, then consider getting it fixed.
But, if it seems to be a deliberate decision, then you’ll want to consider the pros and cons before you try to change things.
I touched on this before, but every time you charge a battery, you shorten its overall life.
Like I said before, charging a battery causes a chemical change, internally.
You don’t chemically change the whole battery with each charge.
Instead, a little bit of the battery is metabolized every time it is charged.
Now, manufacturers know this, and they put a lot of effort into making batteries that can handle a lot of recharges, but eventually, nature wins, and the battery wears out.
The primary reason to limit the charging capacity to 80% is to prolong the battery’s lifespan.
Since the last 20% of charging takes more power, it’s harder on the battery.
You metabolize more of the battery with that last 20% than you do with the 80% of charging that happens first.
So, when you cap charging at 80%, you dramatically lower the overall strain on the battery.
Doing this can extend the life of a battery by a year or more.
This move comes with a very clear cost.
If you aren’t fully charging the battery, it can’t go as long between charges.
Sure, you’re making the battery last longer in terms of wear and tear, but that comes at the cost of operational ability right now.
Your battery can’t run as long without a recharge, so you’re more attached to the power cord than you need to be.
If you’re trying to use the computer on the go and without frequent charging access, it can be a pain.
That’s the real con in this situation.