Just like your car, a riding lawn mower can have a weak or dead battery. Often this is because the lawn mower has been in storage or an electrical component has been left on accidentally. Jump-start a riding mower with a good battery you have on hand or your car. When using your car, the car must not be running. A running car battery provides too much amperage for your mower. This could damage your mower battery or electrical systems. Wear work gloves to prevent contact with battery acid.
Position the riding mower on a level surface with plenty of room to work around the front of the mower. Some riding mowers have a rod on the lower rear frame to disengage the mower drive. Pull the rod out and the mower will push easily to where you can work on the mower.
Open the hood, if your battery is under the hood. Some mowers place the battery under the driver's seat. Lift the rear of the seat forward to access the battery. Place a battery with a full charge near the mower battery. If using a car, park the car near the battery on the mower. Turn the car off, remove the ignition key and raise the car hood.
Attach the red ends of the jumper cables to the positive terminals on each battery. The positive terminal is the terminal with a "+" stamp on or near the terminal. Place one black end of the jumper cable to the negative terminal on the good battery. The negative terminal is the terminal with the "-" stamp on or near the terminal.
Attach the other black end of the jumper cable to a solid piece of the mower frame away from the fuel tank area. Engage the clutch on the mower and ensure that the mower is in neutral. Turn the ignition key on the mower to start the mower.
Remove the black cable from the mower frame, and remove the opposite black cable from the good battery. Remove the red cable ends from the batteries, starting with the mower battery.