A weak battery is a common problem for riding mowers, especially at the start of the mowing season. You can jump start the lawn mower battery with your car since the mower and the car both have 12-volt batteries. Unlike your car, a lawn mower will not charge the battery while it is operating. The battery will still be weak at the end of the day. When you are done with cutting the grass, you should charge the battery overnight with a charger or take the battery to an auto parts shop so they can charge it for you.
Drive the vehicle with the good battery close to the front of the mower. If you need to push the mower to the vehicle, disengage the transmission of the mower. There is a rod on the lower rear of the mower. Pull the rod out to disengage the mower and push the mower to the vehicle. Push the rod back in to engage the transmission.
Engage the mower parking brake and place the mower in neutral. Raise the mower hood and the hood of the other vehicle. Turn off the charging vehicle. The amps that a car will create may be too much for your lawn mower.
Connect the red cable ends of the jumper cables to the positive terminals on both batteries. The positive terminal will have a "+" sign either on or near the terminal. Use caution and do not touch the chassis with the red cable ends.
Secure one of the black ends of the jumper cable to the negative terminal on the good battery. The negative terminal will have a "-" sign either on or near the terminal. Place the other black end of the jumper cables to a good chassis ground away from the fuel tank. Some mowers have a plate on the left side of the driver area to attach the cable.
Push in the clutch pedal and start the lawn mower. Once you start the mower you will need to remove the jumper cables in the reverse order. Remove the black end from the mower. Remove the black end from the vehicle jumping the mower.
Remove the red end from the charging vehicle and finally remove the red end of the jumper cables from the lawn mower.