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Can You Jumpstart a Lawn Mower with a Car? Steps, Risks & FAQs

cropped man mowing lawn with lawn mower

Nothing beats an electric start lawn mower for convenience—until the lawn mower doesn’t start when you pull it out of the garage! When this happens—and it will eventually—jumpstarting the lawn mower battery with a car is possible and safe when done correctly.

There are a few times when you shouldn’t use a vehicle because it’s unsafe. If you have a push mower with a six-volt battery, you cannot use a car.

If you’re unable to use a car, a booster pack or battery charger are two other options. In addition to using your car, we’ll discuss these other methods in this article.

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Using Your Car to Jumpstart Your Lawn Mower

lawn mower on grass
Image Credit: Skitterphoto, Pexels

Most ride-on lawn mowers have 12-volt battery systems, so you can jumpstart them with a vehicle. Anytime you’re boosting a battery, there are several inherent risks to think about.

Jumpstart Risks

Proper precautions should be taken to avoid these risks. Ensure that you wear appropriate protective equipment such as gloves and eye protection when jumpstarting. Also, inspect the battery before jumping it.

  • If a battery is damaged, it may explode when jumped.
  • Jumpstarting anything—vehicle or lawnmower—poses a risk of damage to both electrical systems.
  • There are usually sparks that can result in a fire if there is anything flammable around.
  • Voltage spikes from jumpstarting a battery can damage the battery and prevent it from charging properly in the future.

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The 4 Steps on How To Jumpstart Your Lawn Mower

red lawn mower in the field
Image Credit: Piqsels

Using jumper cables is not complicated but should be done in a specific way to avoid damage to each battery and electrical system. Once you’ve confirmed you’re dealing with two 12-volt batteries, here are a few simple steps to follow.

1. Prepare the Battery and Vehicles

Before hooking up the battery for a jumpstart, ensure that the battery isn’t damaged. In addition, use steel wool or a terminal cleaner to ensure that the battery posts are free from dirt and corrosion.

Both the car and your lawn mower should be off to help minimize the chances of a current or voltage surge.

Car battery
Image Credit: 13_Phunkod, Shutterstock

2. Hook Up the Jumper Cables

Starting with the car battery, hook up the positive clamp. This clamp will often be red and designated by a “plus” symbol. Then do the same on your lawn mower.

The second connection is the negative or ground clamp on your car. Typically, this clamp is black and designated by a “minus” symbol. Do the same on the lawn mower’s battery.

Once the batteries are connected with jumper cables, allow everything to sit for a couple of minutes before turning the car on.

3. Turn the Car On

Start your car and allow it to idle for a couple more minutes before attempting to start the lawn mower.

If the lawn mower doesn’t start, try letting it sit for a couple more minutes with the car idling. But if it does start, wait a while (at least 30 minutes) before turning it off so that its charging system can recharge the battery.

jumper cables up close
Image Credit: FlashMe Photography, Shutterstock

4. Remove Jumper Cable

While the lawnmower and car are still running, it’s now safe to remove the cables. Simply reverse the steps from putting the cables on.

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Things to Consider When Jumpstarting the Lawn Mower

cropped black and blue lawn mower on grass
Image Credit: Skitterphoto, Pixabay

If the mower won’t start after being connected to the car for several minutes, it’s likely the battery is toast, and you’ll need to buy another one. This is common if a lead-acid battery is allowed to drain completely and sit like that for an extended period.

Another thing to consider is having to boost the battery repeatedly. If this is the case, you’re better off replacing the battery that’s on its way out.

Unfortunately, if a new battery still needs to be boosted, there is likely something wrong with your lawn mower’s charging system, and it will need to be diagnosed and fixed by a small engine mechanic.

Alternative Jumpstart Methods

If you’d rather avoid the potential hazards of boosting with a car, there are two other common options with built-in safety features.

Booster Pack

A booster pack is a great option because they are easy to transport, and most are designed to prevent voltage surges. Also, if your lawn mower has a 6-volt battery, many boosters are available that switch between the two voltages.

Battery Charger

Using a battery charge is the safest option because instead of forcing power into a battery to start it, the charger sends a lower but steady amount to recharge the battery.

This is also a great way to determine if you need to replace the battery. If it’s still dead after leaving it on a trickle charger overnight, there’s no chance it’s coming back to life.

garden flower divider FAQ: Jumpstarting Lawn Mowers with Cars

Why can’t I jump a 6-volt battery with a 12-volt system?

Technically, it’s possible to jump the lower voltage battery with your car. However, the risk for damage or injury goes way up if not done correctly. So, it’s best to assume it’s not possible and avoid it unless you know exactly what you’re doing.

Gas Near Lawn Mower_shutterstock_Erica Allin
Image Credit: Erica Allin, Shutterstock

How long does it take for a lawn mower battery to charge?

If you jumpstart the lawn mower battery, it’s a good idea to let it run for at least 30 minutes. Ideally, you’d want to run it for 1–2 hours, though.

Once you’re done mowing the lawn after jumpstarting the battery, the best thing to do is throw the battery on a trickle charge overnight. This ensures the battery is at full life, which can assist in determining whether it needs to be replaced or not.

Why is the lawn mower turning over but not starting?

When you turn the key and the engine cranks but won’t start, it’s likely that you don’t have a battery problem. A common culprit in this situation is bad fuel. As fuel ages, it degrades, and this bad fuel can wreak havoc on the fuel system. In turn, the engine won’t fire up as it should.

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So long as your lawn mower has a 12-volt battery, you won’t have any problems boosting it with your car. And as long as you take the proper precautions, it’s a relatively safe procedure. Keep in mind that you may need a new battery altogether, but you can usually get a ride-on lawn mower battery for less than a hundred bucks.

Featured Image Credit: Pexels, Pixabay


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