Is It Safe To Jump Start A Lawnmower With A Car?

It’s common for lawn mower owners to turn their ignition only to hear a hushed clicking noise, especially after the winter. This is because lawnmower batteries aren’t infinite, and they usually die at the most inconvenient times.

If this happens to you, you may wonder, “Is it safe to jumpstart a lawnmower with a car?” The short answer is yes. Most people will jumpstart their lawnmowers using their cars’ batteries if they don’t have access to a battery charger.

In this article, we’ll dive deep into how safe it is to jumpstart a lawnmower with a car and the precautions you should take while doing so. We’ll also give you a run-through of how to jumpstart a lawnmower safely, so stick around!

How Safe Is It to Jump Start a Lawn Mower With a Car?

It’s relatively safe to jumpstart a lawnmower with a car as long as its battery and car battery are compatible.

Most lawn mower owners don’t have spare batteries on hand or are able to immediately go to their local hardware store to buy a replacement battery. One accessible alternative is jumpstarting the mower battery in the same way you would a car.

Car batteries are typically 12 volts, as are most lawnmower batteries. To find out your mower’s battery details, look for a sticker or a stamp on the battery casing that indicates the battery voltage.

Don’t forget that if the two batteries aren’t compatible, you shouldn’t attempt to jumpstart your lawnmower. The electrical system polarity of the car battery and the grass cutter’s battery can result in irreparable damage to either battery and potentially injury.

Another thing to remember is that mishandling either of the batteries can expose lawn mower owners to battery acid and lead. Because both materials can cause skin irritation and burns, taking precautions is critical.

As a result, provided that you’re cautious and follow the proper procedure, it should be safe to use a car to jump-start a lawnmower.

Safety Precautions to Take While Jump Starting a Lawn Mower With a Car

The process of jump starting a lawnmower battery with a car can be safe and straightforward if you make sure of the following:

Turn Off Lawn Mower and Car

Your first step should always be to disconnect the mower from all power sources, whether you’re jump-starting it or doing any checkups.

In addition, before you jump-start the grass cutter, you must turn off your car. This is because the alternator may overload the lawn mower’s battery if you start the car first, causing further damage.

Check Battery Is Indeed Flat

Before condemning the lawn mower’s battery, you should check for loose connections or worn cables. Unfortunately, some of those problems can mimic the symptoms of a flat battery.

Loose Connections

Lawnmower batteries deal with constant vibrations, which can loosen the wire connections to the batteries. A loose battery connection disrupts electricity flow and may emulate the symptoms of a flat battery.

You can prevent loose battery connections by regularly checking the lawnmower battery. Typically, you can find the battery under the mower’s seat.

Lift the seat and gently tug the battery wires. If any wire comes loose, you need to attach and tighten them securely.

Damaged Cables

You should check your lawn mower cables for any damaged or dirty wires. If you have any worn cables, they’re most likely the cause of your mower acting like it has a flat battery.

Lawn Mower Battery Is Too Old

If you’ve had your grass cutter for a while, there’s a good chance it won’t start because the battery is too old.

A lawnmower battery typically lasts three years before dying. Even if you try to jumpstart it, a dead battery probably won’t start. 

In this case, it’d be better to recycle the battery and buy a new one for your lawnmower.

Clean Battery Terminals

If battery terminals and cables are dirty or corroded, the electricity flow meets resistance, which can prevent recharging. You should find a white, crusty build-up on the battery terminals or cables.

Start by wearing your protective gear and sprinkle some baking soda on the source of the issue. Then, carefully spritz some water, allowing the baking soda to dissolve the corrosion and dirt.

After a few seconds, gently scrub the baking soda solution with a wire brush and wipe it all away with a cleaning rag.

If you notice that the battery is leaking, you should immediately remove it and install a new one.

Wear Protective Gear

Wearing protective gear isn’t required if you take all precautions and follow the proper procedure to jumpstart a lawnmower with a car.

Still, it’s always better to be safe than sorry, so you can wear goggles and gloves to protect your eyes and hands from any battery acid.

How to Safely Jump Start a Lawn Mower With a Car

Now that you’ve taken your precautions, the best way to ensure your safety is to jumpstart the mower properly. Below is the step-by-step procedure for starting a mower. 

That said, it’s best to consult with your mower manufacturer to find out what they recommend on how to jumpstart it. 

Step 1: Connect the Batteries

There’s a specific order that you should follow when connecting the batteries with the jumper cables.

First, attach one of the red cable clamps to the car battery’s positive terminal. Then, attach the other end of the red cable to the mower’s battery’s positive terminal.

Next, attach the black clamp closest to the car battery to the negative terminal and the other clamp to the lawn mower’s frame. Don’t connect it to the mower battery’s negative terminal.

You can now start the car and let the lawnmower battery charge.

While attaching the jumper cables, make sure you’re not directly standing over the battery. Some sparks may fly around, so keep your face as far away from them as possible.

Step 2: Start the Lawn Mower

After a few minutes, try starting the mower to see if the battery is charging. It should start immediately.

If that’s not the case, you can charge it for a few minutes longer and try again.

Step 3: Disconnect Jumper Cables

After the battery has had time to charge, disconnect the jumper cables in reverse order.

Begin with the black clamp connected to the mower’s frame, followed by the other clamp on the car battery’s negative terminal. Next, remove the red clamp attached to the mower’s positive terminal, then the one attached to the car’s positive terminal.

If the lawnmower dies after a few minutes, you should get the alternator and voltage regulator checked.


Jumpstarting a lawnmower with a car isn’t only safe, but it’s also easy. Lawnmower batteries work the same way as car batteries do, so a car can jump start any grass cutter with a 12-volt battery.

What’s more, if you follow safety precautions and the proper way to jumpstart a battery, there’s little chance of an incident. 

Jumpstarting a lawnmower isn’t difficult, but it does involve electricity, which necessitates caution. After doing it once, you’ll never have to worry about a dead battery preventing you from mowing the grass.

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