All gas-powered lawn mowers run on gas, oil, and batteries, and knowing how to change your mower's battery yourself can save you time and money. Unlike many battery-powered devices, however, lawn mower batteries are very specific to the model and type of lawnmower. Make sure you get the correct type and follow these steps to replace the old one.
Step 1 - Find the Battery
Lawn mower batteries are located in one of two places: under the hood or under the seat of the mower. In order to find it, turn off your mower and remove the keys. Look in both of these places, and then find and release the latch for the cover so you can access the battery. Remove any tie-down strap or bar holding the battery in place.
Step 2 - Remove Battery Cables
Whenever you remove a battery, always begin by removing the black, or ground, wire. If the connectors are corroded, use a stiff wire brush to brush them clean. If the battery itself is severely corroded, use a baking soda and water paste and apply it to the terminals. Allow it to sit for a few minutes before using the brush and clear water to rinse off the corrosion. Dry any water with a soft rag. Be careful not to get the mixture or water into any battery cells and rinse thoroughly before removing. Baking soda neutralizes battery acid and will neutralize your battery if it gets inside the cells.
If the connectors remain tight, use a flat head screwdriver to slowly and carefully pry the connector apart and away from the terminal. Do not force the cable off, as you can pop off the connecting terminal. Once the negative (black with negative sign on terminal) cable is removed, then remove the red (positive with plus sign on terminal) cable.
Step 3 - Replace The Battery
Once you remove the battery from the holder, clean out (rinse) any corrosion or debris and dry the holder. If the holder is metal and shows signs of rust, sand and paint the rust spots as battery fumes can accelerate rust.
Place the new battery into the holder and attach the tie-down strap or bar. When re-attaching the cables to your battery terminals, always start with the positive (red) cable. Connect it to the positive terminal and tighten the bolt to secure it. Follow this by attaching the negative (black) cable to its respective terminal as well.
Replace the cover for the battery and test it to be sure everything is working.
Tips for Replacing a Lawn Mower Battery
Not all batteries are created equal, so as mentioned previously, make sure you get the right battery for your specific model and type of lawn mower. Also, check your battery for corrosion at least once a month, and read your owner's manual to ensure that you are charging your battery correctly and maintaining it properly.