If you primarily use a laptop, you may have had people shaking their heads because you keep it plugged in for long periods of time. They may cite old computer wisdom that you shouldn't keep a laptop plugged into the mains continuously for long periods of time or you risk damaging the battery. The usual rule of thumb is to remove the battery and run it on AC power only. Now that we're in a world of laptops with built-in batteries, is that advice still valid?
SummaryWill this overcharge the battery?Will the battery degrade further?How much will the battery degrade?Heat is the main enemyWhat to doA case for recalibrationIntake issues
As you can see, if the battery is kept at 100% for more than a year at 25°C, 20% of the total battery capacity is lost (80% recoverable). However, this is not the only information we can glean from this table. You might be tempted to compare a 100% charge to 40% charge, but there's something even more important to take away from this:the magnitude of the effect of temperature on the battery!
From the table above, we can see that the main factor that caused the stored batteries to lose their charge level was due to the heat they were exposed to. A battery stored at 100% charge for one year at 0°C will lose 6% of its capacity, while a battery maintained at 60°C loses 40%. That's a huge difference and a sign that a major player in maintaining a 100% healthy battery is keeping it cool. Battery University goes on to say:
In simpler terms, this means that keeping your battery at 100% and exposing it to high temperatures can put more strain on the battery than if you constantly charge and discharge it. Therefore, we can see that the main villain of keeping your battery always plugged in isn't that it's always exposed to energy – it's that it becomes sensitive to high temperatures in a constantly full state. P>
This then makes the answer to this age-old question very simple. If you have a low-end laptop that doesn't generate much heat and you're in a fairly cool climate, you should be able to sustain the battery at 100% and only see a gradual degradation.
However, if you are using a high-end laptop to render a graphically intense game, the heat from the laptop can damage the battery when fully charged. In this case, it's probably best to remove the battery (preferably at 40% charge!) to prevent damage. Try checking your laptop's system temperatures using software such as Speccy to get an idea of the laptop's temperature.
Before you go on and keep the battery at 100%, though, it's worth bearing in mind that you might want to recalibrate your battery from time to time. By doing so, you can ensure that your laptop will have an accurate reading of your battery level when you (possibly!) unplug it from the mains. You can read all about recalibration in our handy guide.
Leaving your laptop always plugged in gets mixed reactions from users and manufacturers, and it can be confusing to get a straight answer. Although there are different factors involved, heat is one of the main killers of fully charged batteries. Keep your battery cool, and if you can't, remove it to prevent further damage.
Are you going to keep or remove your battery? Does your laptop give you the choice in the matter? Let us know below!
