Many laptop owners use their devices as desktop computers, leaving them plugged in all day. Modern power management systems protect the battery from overcharging, but keeping it constantly at 100 per cent charge and exposing it to high temperatures can accelerate wear and tear.
- Modern laptops automatically stop charging once they reach a set charge level.
- High temperatures and prolonged use at 100 per cent capacity accelerate battery ageing.
- Limiting the charge to 60–80 per cent helps to preserve the battery’s original capacity.
What happens when a laptop is constantly plugged in to charge?
Modern laptops are fitted with lithium-ion or lithium-polymer batteries and electronic power controllers. When the battery is fully charged, the controller stops charging it, and the laptop mainly draws power directly from the mains adaptor.
Therefore, it is fine to leave a fully functional laptop plugged into the mains even round the clock. The problem lies not in overcharging, but in the gradual chemical degradation of the battery.
Regardless of how intensively it is used, a battery loses its capacity over time. This phenomenon is known as calendar ageing.
At the same time, the correct power settings allow you to increase MacBook Air battery life and other modern laptops.
Why does a battery wear out more quickly when it is 100 per cent charged?
Leaving a lithium-ion battery fully charged for a prolonged period places additional strain on its internal components and accelerates irreversible chemical processes.
A combination of a fully charged battery and high temperatures is particularly detrimental. This is particularly relevant for gaming laptops, mobile workstations and devices used for video editing or other resource-intensive tasks.
The following factors have the greatest impact on the rate at which a battery degrades:
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long-lasting 100 per cent charge retention;
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the laptop regularly overheating;
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frequent discharging down to 0%;
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number of charge and discharge cycles;
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natural ageing of the battery.
However, each time the charger is connected, this is not counted as a separate cycle. One full cycle corresponds to the total utilisation of 100 per cent of the battery’s capacity.
To what level is it best to charge a laptop?
For laptops that are plugged in most of the time, the best solution is to limit the maximum charge level.
| Battery level | Usage scenario |
|---|---|
| 60% | Continuous operation from the mains |
| 80% | Daily mixed use |
| 100% | Travel and power cuts |
Charging to 100 per cent is not dangerous. If a user requires maximum battery life, there is no need to artificially limit the available battery capacity.
How to limit charging on laptops from different manufacturers
Most major manufacturers have incorporated special features to reduce battery wear and tear.
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ASUS — Battery Health Charging in the MyASUS app.
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Lenovo — Conservation Mode in Lenovo Vantage.
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Dell — ‘Primarily AC Use’ in the power settings.
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Microsoft Surface — Smart Charging on compatible models.
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Apple MacBook — Optimised battery charging in macOS.
Depending on the model, these functions allow you to set a maximum charge level or automatically manage charging in line with your usage patterns.
Should you unplug your laptop from the mains from time to time?
There is no need to deliberately discharge the battery every day if the laptop is plugged in. Doing so only increases the number of charge and discharge cycles.
It is far more effective to set a maximum charge limit, ensure the device is properly cooled, and use a compatible charger with sufficient power.
It is also not advisable to leave a laptop running on a blanket, sofa or other surfaces that block the ventilation slots.
How to check the condition of a laptop battery
In Windows, you can get a detailed report on the battery’s condition without installing any third-party programmes.
To do this, you need to:
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Open the Windows Command Prompt.
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Enter a command
powercfg /batteryreport. -
Press Enter.
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Open the HTML report you have created.
You need to find two figures in the document:
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Design Capacity — the battery’s factory capacity.
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Full Charge Capacity — current maximum capacity.
For example, if the initial capacity was 50,000 mW·h and the current capacity has fallen to 40,000 mW·h, the battery has retained approximately 80 per cent of its initial capacity.
MacBook users can check the battery status in the macOS System Preferences under the «Battery» section.
