Lawn mower batteries can lose the capacity for storing a charge if the battery is stored for a long time without external charging. When this happens, permanent damage may force the battery's replacement. Exercise caution when choosing the replacement, as not all lawn mower batteries utilize the same voltage (6 volts and 12 volts typically are used). Consult the manufacturer's specifications for the correct battery and then install it.
Wear the safety glasses whenever performing any type of work on a battery or related equipment. Small particles can become airborne during the installation process.
Set the battery on a firm and level surface. Clean the battery terminals with the steel brush. The terminals must have a bright metallic finish to efficiently conduct electrical power.
Remove any signs of corrosion from the battery terminal connectors. Corrosion can appear in the form of either a green or white powder covering the connectors. These connectors must also have the same bright metallic finish as the battery terminals. The cleaner the connectors, the better the conduction of electricity.
Place a thin coating of the corrosion inhibitor over battery terminal surfaces and the mower's battery connectors. Petroleum jelly or petroleum-based grease will work if no corrosion inhibitor is available.
Insert the battery into the lawn mower's battery tray. Secure the battery into place with the provided straps or mechanical bracing. Lawn mowers have varying methods of attachments. All batteries must be secured into place in any movable device.
Connect the battery electrically. Attach the red cable from the lawn mower to the positive (+) terminal on the battery. Use the correct size end wrench to tighten the battery connector clamp to the terminal post.
Secure the black cable of the lawn mower to the negative (-) terminal on the battery. Tighten the cable clamp.