A:First, find out the part number of your old battery or the model name of your laptop (e.g. 'Asus X421FF') and then match with our product compatibility table. Second, please compare your old battery with our product images to make sure their shapes are the same. Finally, check the voltage (rating) is the same as the old one. For more details please click How to find one correct battery for my laptop?

A: Generally speaking, it will not cause any damage without removing battery when you connect the power supply. Because the battery will not be charged anymore after it is fully charged. Oppositely, it will turn to the use of power supply system. However, when your notebook has run for a long time at high speed, you’d better remove your battery out of your laptop owing to the internal overheating. Otherwise, it is harmful.

A: There is no need to charge your new Asus X421FF battery for 12 hours for the first time use, because lithium-ion battery has no memory effect. So you only need to charge and discharge it normally. What’s more, you should avoid exhausting the battery power and then recharge, because it will bring a lot of damage to your battery. Therefore you have to charge it when remaining power nearly 10-20%. By the way, if your battery has not been used for a long time, please charge it once a month, keep the remaining power about 50% and then store it in a dry and cool environment.

1 Turn your Asus X421FF laptop over.
2 Find out the laptop battery release button lock.
3 Press the battery release button, gently pull the battery out of the laptop.
4 Insert the battery into the slot. Push your Asus X421FF battery to the laptop and secure it in place.

1 Tweak Your Built-In Power Saving Options.
2 Adjust the brightness of your laptop display as much as possible within an acceptable range.
3 Disable unnecessary programs that draw energy from your notebook.
4 Keep your laptop and battery in a cool dry place (heat may destroy a battery).
5 Avoid Full Discharges.