for 4hours will be automatically be reduced to 30min or an hour. While some laptops are already acting as a desktop (you can't use except its connected to electricity).
But I'll show you two method of restoring your laptop battery.
1. Re-calibrating Method: This method works better if your battery never charges to 100% (no matter how you charge it, it always stop at 90+%) or if the OS says you have 25 min of battery remaining, but the
computer dies either much sooner or much later.
New Method of Re-calibrating Your Laptop Battery
Step 1: Charge your battery to 100% or to whatever max percentage it can reach and leave it there for about 2 hours to cool down.
Step 2: Now disconnect the power and let the battery drain. There seems to be two views about how to do this. You can either let the battery run down all the way until the laptop dies or you can set it so that it goes to sleep or hibernates around 3 to 5%. Either way, you want to make sure the display stays on until it either dies or goes to sleep.
Step 3: Let the computer remain turned off for anywhere between 3 to 5 hours.
Step 4: Turn it back on and let it charge all the way to 100%.
2. Freezing Method: This sound crazy but it works like charm. Even a smartphone battery tends to last longer when its under a cool environment than when its under the scorching sun.
Step 1: Take your battery out and place it in a sealed Ziploc or plastic bag.
Step 2: Go ahead and put the bag into your freezer and leave it there for about 12 hours. Some people suggest leaving it for longer, but I wouldn't leave it for more than 24 hours.
Step 3: Once you take it out, remove the plastic bag and let the battery warm up until it reaches room temperature. Be sure to wrap it in a towel and wipe away any condensation as it warms up.
Step 4: Reinsert the laptop battery and charge it completely.
Step 5: Once charged, unplug the power and let the battery drain all the way down.Now repeat steps 4 and 5 at least 4 times: charge all the way to full, and then discharge completely. After this, you should see a dramatic turnaround in your battery cells.
Note: this method works best on NiCD or NiMH batteries. Do not try this on lithium battery.
Finally, Make sure you unplug your charger once your laptop charges to 100%... leaving it plugged in after fully charge kills the battery cells.