CMOS battery low of a mecer laptop

first you get to open your laptop with a screwdriver and find where is the battery located in the motherboard but before you replace the battery just write down the specifications of it and go store so when you actually take the battery out of the board you can just replace it shortly because the internal clock and several settings need that battery to keep it save in the memory watch out the keyboard because in some laptops is hard to put back in place if you just take it off the case