How to Jumpstart a Lawnmower Battery With a Car

If you let your push or ride-on mower stay parked for too long, chances are the battery will run out and it won’t crank at all until you recharge the battery.

Better still, you can jumpstart it using your car – if you don’t have an electric battery charger.

Is It Safe to Jumpstart a Lawnmower With a Car?

You can use your car to jumpstart a lawnmower as long as your mower uses a 12-volt battery. Check your mower’s battery voltage before attempting a jumpstart. You should also inspect the battery and ensure that it isn’t leaking or swollen to avoid unwanted explosions.

How to Jumpstart Your Lawnmower Safely

Before you start, you will need jumper cables. If you don’t have them, you can grab a pair here.

  • Move your mower as close to the front end of your car as possible. It is best to drive your car out of the garage before starting the process
  • Ensure that your lawnmower and the car aren’t in contact. Any slight contact could lead to a catastrophic short circuit
  • Use some steel wool to clean off any corrosion off your lawnmower’s battery terminals
  • Use the jumper cables to connect your car’s battery to the mower’s battery

Connecting the two is one of the most delicate steps in the procedure. Here is the right way to do it.

  • Connect one end of the red cable clamp to your car battery’s positive terminal and connect the other side of the cable to the riding or pushing mower’s battery (positive terminal)
  • Connect the black jumper cable to the negative terminal of your car and secure the other end of the cable to a heavy and unpainted part of the lawnmower’s engine. Don’t make the mistake of attaching the negative cable to the lawnmower battery’s negative terminal
  • Start your car and wait for the lawnmower battery to get some juice. This could be a couple of seconds but wait for a minute or two to be on the safe side
  • Start the lawnmower with the car’s engine still running. The mower should start right up if it doesn’t have any other problem. If it doesn’t you can leave the two hooked up for 5 minutes before trying again

Common Mistakes to Avoid When Jumpstarting

There are three common mistakes people do when jumpstarting lawnmowers or other cars. You should avoid them at all costs.

  • Hooking up the negative terminal of the jumper cable to the negative terminal of the battery bypasses the fuse system and could easily short circuit the two batteries. Hook it up to an unpainted part of the dead car/mower’s engine instead
  • Failing to start the car that has juice sooner could leave you with two drained batteries. Actually, if you don’t trust your car battery’s capacity, you can just crank your car before starting the jumper cable connection
  • Starting the lawnmower too soon before the battery gets time to juice up

How Long Should a Lawnmower Battery Last?

The average lifespan of a well-maintained lawnmower battery is 3 years. Cleaning your battery often, coating the terminals with anti-corrosion gel, and charging it frequently when in long term storage should help it hit three years.

Why Does My Lawnmower Battery Keep Dying?

If your lawnmower battery keeps on dying, chances are it’s already worn out and you need a replacement.

Check this too: Toro Lawn Mower Troubleshooting

Can You Jumpstart a 6 Volt Battery With a 12 Volt Battery?

No, you cannot. This will fry the electrical system of the 6-volt lawnmower and the short circuit load can also affect your car.

If you are not comfortable using your car to jumpstart your lawnmower, you can always purchase an electric battery charger jump starter. This will hook up to your dead battery to 12v or 6v power without the hassle of hooking up a car to the lawnmower.