Keeping laptop plugged in and charging even if the battery is full - Is this fine?

Keeping the battery always in not good. The life of the battery will come down and you may have to change the battery frequently. Experts say that keeping the charge between 40 % to 80% is the best for long shelf life. Start charging the battery when the level of charging reaches 40%. Charge the battery till it comes to 80% of its full capacity.
But there are some models where the power will get cut off automatically when it reaches 100%. In these models even you keep the battery charging on also no problem.
Most recent generation laptop batteries are either lithium-ion or lithium-polymer. These batteries will have many charge cycles. So if we keep them always on charge condition also it may not harm the battery. But these batteries also will get spoiled easily if you allow them to get discharged completely.
Please follow the following tips irrespective of model and make. That will give you a better life span
1. Try to keep the battery level between 40 per cent to 80 per cent
2. Please see that your laptop doesn't get too hot. See that your cooling fan is working properly.
3. Select battery saver or eco mode.
4. DIsable unused devices.

Keeping laptop plugged in and charging even if the battery is full is not good.
The Laptop components are very closely positioned for obvious reasons of space. The battery is placed very close to the vital parts like the central processor. The parts get heated during the Laptop working. In addition the battery also gets heated up during charging. This adds to the heat inside the Laptop and especially the processor etc gets heated up more as the ventilation is not that much in a Laptop. Hence in the long run this affects the performance and also damages the vital parts of your Laptop.
There is another risk of sparking as unknowingly the plug chord may be subjected to your pull and movement. This apart, working with such devices directly plugged to a main current source is also risky.
The ideal way is to charge the device to the maximum and then take out from main electric plug and work with the device. When the charge comes down and reaches a level of say 30 percent, take precautions of shutting down properly and take it out for charging.

Normally we see many people use laptop or mobile while charging. But it is not advisable as the variation in power supply would affect even to the level of bursting. I read in newspaper that a girl was listening music in her bed through earphones in her mobile by keeping the mobile in charge. By that way she slept. Suddenly mobile burst out due to overload and she got heavily damaged in face with burning injury .

Leaving the battery plugged despite the same being fully charged will reduce its useful life. It would affect the life of battery. Lithium ion battery being used in Laptop has fixed number of charging cycles- somewhere between 600 - 800 in terms of laptop battery.
Thus to maximise the length of time of its retention of charge, it would be better to minimise the time of remaining being plugged despite the same fully charged - if not possible to eliminate it altogether.
While constantly discharging and recharging fully would be a better option than leaving the battery plugged in. Most of the laptops other than made by the Apple have removable batteries. These laptops can run without the battery being charged. Remove it physically and the same can run on AC power. This would eliminate the problem of having it plugged in while fully charged . This would also eliminate the unnecessary use of charging cycle.

Once the battery is fully charged it is a general practice to remove the charger. Then we work in laptop till the battery reaches a low level say 5-10% and then again we have to charge it for the next use. Using battery this way enhances its life and avails all the charging cycles as designed for that battery.

When we do not remove the charger even after the battery is charged fully then initially nothing happens as battery stops getting further charging and the laptop starts to work on the mains power and battery remains at 100%. But if we keep it like that for a long time then two things happen which are detrimental for the battery life. First thing is that the battery heats up due to heat inside the laptop and that is always an adverse thing for the health of the battery and second is that keeping a battery forced at 100% is not advisable as whatever power is trickling out of it would be again given by the mains power and that would interfere with the charging cycles that are supposed to start only when battery is too low or discharged fully.

If there is an emergency like battery gone bad then there is one trick that people use especially in areas where there is continuous mains power supply available or they have got an inverter installed in their house and the trick is that they remove the battery and work on mains. I had a laptop in which battery had gone bad 2 times and it was replaced in warranty but third time it was not under the warranty and I decided to use it without battery just on mains as I did not take the laptop anywhere. I worked like that for 3-4 years without any battery in it.

Another thing is that if due to some reason you want to keep your 100% charged battery for some time in the drawer then you can run the laptop on mains and then only when you want to go out put the battery back and take your laptop with you. However please remember that whether you use your battery or not it always loses its life albeit less in comparison to when it is used. So, keeping it out like that intermittently would increase its life may be by 15-20% at the most. So, it is not a very advantageous proposition.

Keeping your laptop battery plugged in even after your laptop is 100 percent charged is not okay. It will decrease your performance of your laptop battery, day by day, and months by months that depends on how you use it, and then your battery will not work at all. How will it decrease?

Suppose you bought your original laptop with your original battery fitted inside. You started overcharging your laptop battery that means you keep on plugging in or charging your laptop battery for 15 days to 1 month and on using your laptop without being plugged in, then you will observe your laptop battery drains faster than the day or month when you brought. Despite this problem, if you keep on overcharging your laptop for next few days or months and on using your laptop without being plugged in, then you will experience your laptop shut down due to low battery even if your laptop battery percentage is not zero percent, say your laptop shuts down when your laptop battery reaches 20 percent on discharging. In this situation the more you overcharge your laptop, the higher will be the rise in battery percentage at which your laptop battery shuts down, which means the discharging time of your battery before laptop shut down reduces until your battery doesn't function at all.

The rate and time of discharging your laptop's battery or the time duration of your battery life depend on the quality of your battery and how frequently or how long you use your laptop. If you use the original laptop battery based on the company of your laptop and model number of your laptop, then your laptop battery life will be longer than the laptop battery owned from 3rd party. If you frequently use your laptop and frequently overcharge your laptop battery, then the discharging time of your laptop's battery or your laptop's battery life will reduce faster than if you don't frequently discharge your laptop and overcharge your laptop.

After so much of explaining how your laptop battery life reduces and how the duration of your battery life depends on the quality of your battery and how frequently you use your laptop, I will give you suggestions for increasing the longevity of your laptop's battery.
1. When you are running your laptop, after charging your laptop's battery to 100 percent, plug off your charger which is used for charging your laptop's battery as soon as you see laptop battery reaches 100 percent. Keep your laptop's battery discharged as long as you see the warning on your laptop that the laptop battery needs to be charged.
2. When you are not using your laptop for some hours, don't charge your laptop because you have the chance of being forgotten to plug off the charger after you see in the indicator that your laptop is fully charged. You may not understand when your laptop reaches full charge after charging your laptop with your laptop off.
3. If you are not using your laptop for a few days, then it is better to take out the battery from your laptop and keep your laptop battery at your protected place.
4. Choose your proper laptop battery. Better use your original laptop battery based on the company of the laptop and the model number.
5. If your laptop battery drains fast and when you observe that your laptop turns off when your laptop battery discharges to a certain percentage, then estimate the time taken to discharge your laptop battery to certain percentage upon using your laptop and then plug in your charger within that time rather than continuously overcharge your battery.

If once your battery is fully charged then it is not good to keep your laptop plugged in or charging. If you keep on charging then your laptop battery may be out of order. But sometimes, you keep on charging may not create a problem as many laptops are automatically closed after being fully charged. So, it depends on the model of laptop. The best way to charge your laptop battery when you find charging percentage is below 10 %. Besides, when you are not going to work on the laptop for a long time then you should do plugged off. One thing is sure that if you charge battery more than required then it may affect your battery life. Lithium-ion battery which is used in the laptop has a fixed number of charging cycle. So, we should charge it seeing its capacity.