The alternator in your car charges the car battery, keeping the battery fully charged. As a battery ages it loses its charge. If you do not start you car for several days you may find that the battery is dead or too weak to turn over the engine. Using a manual car battery charger is one way to charge the battery under these circumstances. Unlike automatic chargers, however, you must keep an eye on the charger and disconnect it from the battery once the battery is fully charged.
Turn the charger power switch to the "Off" position. Position the battery charger near the front of the vehicle and close to an electrical socket.
Connect the positive cable of the battery charger to the positive battery post. The red positive cable on your car connects to the positive battery post. The post also has a "+" stamp on or near the post. The battery charger's positive cable is usually red with a red clamp.
Clamp the negative cable of the battery charger to the car frame or engine block, away from the battery. This prevents sparks around the battery. Do not clip to fuel line, carburettor or sheet metal. The negative cable must clamp onto a heavy gauge metal part of the engine block or frame.
Turn the voltage switch to the voltage of your battery; either 6-volts or 12-volts. Plug the power cord into an electrical socket and turn the power switch to "On".
Watch the charge gauge on the battery charger. The gauge either has a needle that rotates through a charging scale or a series of lights that glow from red to green. When the needle reads a full-charge or the indicator lights are green, turn off the charger power switch.
Unplug the charger power cord from the wall outlet. Remove the negative cable of the charger from the vehicle and then the positive cable. Start the vehicle and put away the battery charger.
If necessary, pull the battery out of the vehicle and set it near the charger. This may be necessary if the vehicle is in the driveway far away from an electrical socket. For safety, connect a jump lead to the negative battery post and then connect the negative charger cable to the other end of the jump lead.
Keep your face away from the battery when making the negative cable connection.