A: First of all, you need to assure the model of your laptop or the part number of your laptop battery. Then look for the battery you need at laptopbatterydirect.net. Finally, you can check whether the battery you find is compatible with your laptop or not on the "Compatibility" table (for example, Sony VAIO VPCZ21S9C). If you don't know how to find the right battery for your laptop, you can click How to find one correct battery for my laptop? for more details. Moreover, you can click the icon "Live Chat" on the right of this page to ask us.

A: You should charge the replacement battery for Sony VAIO VPCZ21S9C laptop before the battery exhaustively discharged, otherwise it will shorten its life. It is feasible to charge the laptop battery before the power is less than 20%. Meanwhile, the battery should be charged in a dry place, and please pay attention to high temperature, which is the biggest threat to battery life.

A: If you let your Sony VAIO VPCZ21S9C laptop battery lay idle for a long time, please charge the laptop battery or discharge to about 40%, and then put it in a dry and cool place to save. Indoor temperature is best maintained at 15 to 25 degrees Celsius because the temperature is easy to accelerate the battery aging either too high or too low. You'd better fully charge and discharge the battery at least once a month. Finally please save it in accordance with the above method.

1Turn off your Sony VAIO VPCZ21S9C laptop and disconnect the AC adapter.
2Release the latch or other attachment devices that hold your battery in place.
3Slide the old battery out of its compartment or storage bay
4Take the replacement battery for Sony VAIO VPCZ21S9C laptop out of the box.
5Slide it into the notch or bay.
6Close the safety latch to lock it into place.
7Reconnect the AC adapter and give the new battery for your Sony VAIO VPCZ21S9C notebook a full charge.