Using a car battery charger correctly is very important.
Turn off the engine and remove the battery from the car. Find a well-ventilated, shady place. If the battery has an openable vent cap, open it; this is not necessary for maintenance-free batteries.
Align the battery terminals correctly. Use the red-pin clamp for the positive terminal and the black-pin clamp for the negative terminal.
Select the 12V or 24V setting according to the battery type.
Plug in the power supply and rotate the current adjustment knob. Increase the current for fast charging and decrease it for slow charging. Do not use too high a current if the battery does not have charging protection. For manual transmission chargers, adjust the charging voltage to the 12V or 24V setting, and then adjust the charging current to 3-5. Observe the charging current; it should be between 4-6 amps. For automatic transmissions, the green light indicates a full charge. For manual transmissions, the ammeter should show less than 0.5A.
Pay attention to the charging time. The entire charging process takes approximately 45-65 hours, with the temperature controlled between 35-40 degrees Celsius. During charging, the process is nearing completion when the terminal voltage reaches its maximum value and remains stable for two hours, and the electrolyte level reaches its highest point and remains stable for two hours. After charging, if the electrolyte specific gravity is not up to standard, adjust it with distilled water or an electrolyte with a specific gravity of 1.4. After adjustment, charge for another 2 hours until the specific gravity meets the requirements.
Additionally, never reverse the positive and negative terminals of the charger when connecting it to the battery. Connect the charger to the battery first, then connect it to the mains power. After verifying that everything is correct, turn on the charging switch. Before charging, check the battery fluid level. Do not add fluid above the standard mark, and do not close the filler neck to prevent gas generated during charging from causing the battery fluid to overflow.