All batteries have a predetermined life cycle. At some point, these electrical storage devices will need replacing. Exercise care and read the manufacturer's specifications for the lawn mower battery. Not all lawn mower batteries are 12 volts. Some mowers will use a 6-volt battery to start and operate the machine. Connecting the battery will not take much time. This task can generally be done in a few minutes with the correct tool. Ensure that the new battery is fully charged and the fluid level is correct prior to the electrical attachment.
Wipe the top of the battery and terminal connection posts with a clean rag. Ensure that the terminal posts are free of corrosion. Corrosion will come in the form of either a green or white powder covering the lead posts.
Clean the posts with a steel brush. The posts should have a bright metallic finish to each terminal connector.
Set the battery into the lawn mower battery compartment. Consult the engine manufacturer's specifications for this location. Various engine types will have a different location for the battery.
Connect the lawn mower battery cables in the following order. Attach the red battery cable to the positive (+) battery terminal post. Secure the black battery cable to the negative (-) battery terminal post. Some mowers may have two smaller wires that need to be connected to the battery. These wires may be a part of the lighting system. Consult the individual manufacturer's directions for these electrical connections. In most cases, the smaller wires will be colored the same as the main battery cables. If so, match the same colored wires with each other on the battery terminal connectors.
Tighten the cable clamps to the battery post with the correct size end wrench. Typically the nuts and bolts range from a 7/16 inch up to a ½ inch in diameter.