Sometimes i forget to switch off the laptop charger and it keeps on charging for about 3 to 4 hours. I want to know if this is harmful for the laptop or its battery.
There may come a time in the life of any laptop where you may get strange symptoms like
1) Hard to move the mouse pointer.
2) Hard to click on any icons or the computer becomes unresponsive.
If so follow these steps:>>
1) Switch off laptop.
2) Disconnect the mains charger.
3) Remove the battery.
4) Try the laptop with just the mains charger.
If the above stops the previously mentioned symptoms then you need a new battery.
I do not know how good or bad "equivalent" batteries are but you could try to look up the battery from its part number if it is on your old battery.
Alernatively look at the label on the bottom of your laptop for the full model number and try something like
"ACER TRAVELMATE C310 battery"
or whatever model your laptop is.
Try EBAY or your favourite search engine like GOOGLE or wherever when trying to fid one. I hope this helps someone out there.
it won't harm the battery Life! Because every time you fully( or to a custom parameter) charge your laptop battery, its automatically get disconnected from adapter. So no power supply to your battery, and your laptop runs on adapter's power(during charging and after, if its connected to adapter) and the battery works as a backup.
By pure experience, I've been doing this for an year now since I mainly play games on my laptop.
And till date never faced a problem.
As others have pointed out, there should be no effect on the battery, since charging stops when the battery is fully charged. The charger itself though, will continue to use some power ("inductive load") and will warm up, so it's a good idea to give it a rest every once in a while.
I would have to say that it may cause premature degradation of performance and quicker wear on the battery if the battery were plugged in and the charger constantly plugged in as well. If the laptop is turned off (not hibernate or sleep) and the charger was left plugged in, then wear would not occur on the battery as much, basically unnoticeable amounts if it were only to be for a few hours. If it were longer, then I would worry about rare cases of overcharging, but the chances are fairly slim. I wouldn't really worry so much about it in this case.
Most inverter boards I have seen in laptops built since 2008 or so should have no negative impact on battery life. Prior to that time, overcharging can reduce the overall life of the battery.
On the more recent models, instead of using a constant trickle charge on the battery once it reaches 90-92% charged, it will keep running at a higher charge rate until it reaches approximately 98%, trickle charge until it hits 100% and if it doesn't reach 100% after about 1 hour, it will disconnect the battery from the circuit so it cannot discharge nor overcharge. If it does charge all the way to 100% within that hour of trickle charging, it will disconnect the battery from the circuit as well. NOTE: It is possible that the battery is not disconnected from the charging circuit, but I ended up getting 0.000 readings on the digital ammeter I was using to measure the charging rate which appears like a total disconnect since the trickle charge stage was able to show current flow.
I have slapped a meter on 2 post-2008 laptops and nearly a dozen pre-2008 models to gather this info, so it should be accurate enough for our purposes unless I ended up using freak builds for testing.
If everything is working properly, as long as AC power is applied, there should be zero drain on the battery under any circumstances even on the most ancient models (such as my Compaq Presario 912 - about 11 years old and one of the tested laptops) and most newer models should be immune to overcharging due to the apparent disconnect.
There should be no effect from "over-charging" because as Jan said, the battery should stop receiving charge after it reaches 100%.
If you think your battery is being charged excessively, perhaps because it keeps getting warm after it says its at 100%, then yes that could degrade long-term performance
Also, all batteries degrade over time and with use. I'd say a normal smartphone user is going to get 1.5-2 years from a battery before it becomes noticeably shorter, while laptops are going to be 2-3 years, unless they're used on battery power almost ever day. In which can life will be lessened.
As for the laptop itself, no, there should be no harm to it.
It mostly depends on the age of the laptop respectively the type of battery in use.
With pretty much every device on the market nowadays having Lithium based batteries there is no harm done by default. Those batteries don't have any memory effect or something ~ more so you should never fully deplete a Lithium battery.
Also it doesn't matter if you have it connected to the power supply for several hours regardless of it's battery charging level. Basically as soon as the battery hits 100% the internal power circuit will bypass it and won't start charging the battery again until it drops below a certain range (around 95%, which should be after several hours, maybe days).
Only on intensive usage when the laptop heats up e.g. playing games you might want to consider taking the battery out especially if it's at 100% charge.
At high temperature the internal structure of the battery starts to break down very fast and for a fully charged battery it may potentially inflate too say the least.