Firstly, the process of checking and replacing a battery involves disconnecting the Car Batteries cables, visually inspecting the battery's state of charge, performing an open voltage circuit test, and conducting a battery load test. When inspecting the battery, use a digital voltmeter to measure the battery's voltage, and remove the surface charge before taking accurate measurements. Also, the battery voltage should be around 12.5 to 12.9 volts. If it is lower, charge the battery before proceeding. Next, perform a battery load test using a load tester, following the manufacturer's instructions. Also, Maintain the load for 15 seconds or less and ensure the battery voltage does not drop below 9.6 volts. If the battery is weak, the tool will indicate this. When replacing the battery, disconnect the battery cables, and remove the hold-down clamp, and the battery. Clean or replace the battery tray if necessary. Install the new battery, ensuring it is identical in dimensions, amperage rating, and cold cranking rating. Finally, reconnect the battery cables in the reverse order of removal.