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Can You Jumpstart A Riding Lawn Mower With A Car? And Is It Safe?

I went to start my mower one cool spring morning, but all I got was a hushed clicking noise. I knew right away it was the battery. But I was so excited and eager to mow that I started to wonder: Can you jumpstart a riding lawn mower with a car?

After a quick consultation with my auto mechanic friend, I had my answer...

You can jumpstart your riding mower with your car as long as your mower has a 12-volt battery. There are some special precautions you should take, however.

First of all, you don't want to fry your mower's electrical system. You don't want to take a bath in battery acid either. Most mower batteries still have lead in them, making safety an even bigger concern.

How To Safely Jumpstart Your Mower

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Step 1 - Move Your Car And Mower Together

Push your riding lawn mower so it is close enough to your car so your jumper cables will reach. Of course, you can drive your car to your mower if that's easier. Just be careful not to get your car stuck. Make absolutely sure that the car and mower are not touching at all. This is critical. You don't want a short circuit. That can damage your car, your mower or both.

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Step 2 - Clean Corrosion From Terminals 

Use a battery terminal cleaner or some steel wool to clean any corrosion off the mower's and car's battery terminals.

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Step 3 - Connect The Batteries

Now it's time to connect the batteries. This has to be done in a precise order, and you never connect the black jumper cable clamp to the dead battery.


First connect one of the red cable clamps to the positive terminal of your car's battery. Then connect the red clamp on the other side of the cables to the positive terminal on your riding mower's battery.

Now connect the black jumper cable clamp on the car's side of the cables to the negative terminal on the car's battery. Secure the black clamp on the other side to a heavy unpainted part of the mower's engine, not the battery.

Start your car and give your mower's battery a few minutes to charge. Don't mess with anything while the batteries are connected.

If something goes wrong, disconnect the red clamp from the car's battery, then disconnect the red clamp from the mower's battery. At this point, everything is safe and you can disconnect the black clamps. Start over again, making sure to follow the proper order.

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Step 4 - Start The Mower

After the mower's battery has charged for a few minutes, start the mower with the car's engine still running. Your mower should start right up. If not, let it charge for another five minutes and try again.

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Step 5 - Disconnect Jumper Cables

Once your lawn mower starts, disconnect the jumper cables in reverse order. That's the black one on the mower's engine, the black one from your car's battery, the red one from your mower, then the red one from your car. If you're not going to go ahead and start mowing now, let the mower run for about 10 minutes to let the battery charge fully.


What If Jumpstarting Doesn't Work?

If your riding lawn mower dies soon after disconnecting the jumper cables, or if it won't start again when you turn it off, the mower's battery may be shot. A riding mower's battery only lasts an average of three years before it will no longer take a charge.

If the mower runs for a while after jumpstarting but dies after a few minutes, the problem may be the alternator or voltage regulator. The alternator keeps the battery charged while the engine is running. The voltage regulator's job is to allow the correct amount of juice through the mower's electrical system.

So how do you tell if it's your battery, alternator or voltage regulator? You have to get them all checked. Most shops that sell mower batteries are equipped to check all three. Some places even check them for free.

How Do I Keep My Mower's Battery From Dying?

First, make sure the three key components of your riding lawn mower's electrical system are working. If you don't know what I'm talking about, you must have skipped the section above. Read it!

You may find that your mower battery needs to be charged or jumpstarted at the beginning of every season.

This isn't uncommon.

Batteries drain slowly when they aren't used. Some people take their mower's battery out and store it on a shelf during the off season. That's better than leaving it in the mower all winter, but there's a better way.

Get a good float charger to keep your battery fully charged all winter and ready to go in spring. They are simple to use. You just plug it into a standard outlet and connect its clamps to your battery. Leave it connected all winter. If you need one, I recommend Black and Decker's model BM3B. I've had one for six years, and it's never let me down.

You can also find a great deal on solar models. These work similarly to plug-in chargers, but they use the sun's energy to keep your battery charged. Sunway Solar makes a great one that is dependable, affordable and easy to use.

Are There Any Other Ways To Jumpstart A Lawnmower?

You may be scared to use your car to jump off your mower. I understand. I was a bit skeptical at first.

Even after talking to my mechanic friend, I had to think about it for a minute.

You're fine as long as both your vehicle and riding mower operate on a 12-volt electrical system. But if you are skittish, there are a couple other ways you can get your mower started.

If you have an extra car battery laying around, you can use it. Just hook it up to your mower the same way you would if it was in your car. You have to have thick cables and really good connections for this to work. That's because you're relying solely on the battery's stored power instead of the strong current from a running car's alternator.

Just hook the cables up and try to start the mower. If it works, that's great. If not, your battery isn't strong enough.

Some riding mowers can be push-started like a car with a manual transmission. I'll tell you how to do it, but keep in mind that this will only work on riding mowers that have a clutch. If you don't have a long, fairly steep hill on your property, you'll need a friend to push. This can be dangerous either way, so use your best safety tool: common sense. Make sure anyone around knows not to walk in front of your path, and be sure there are no obstacles in the way. If you decide to abort while you're coasting down the hill, turn the ignition off and use your brakes.

Assuming you have a suitable hill, push your mower to the top. This is easier with help. Once at the top of the hill, turn the mower so it is facing downhill. Make sure the parking brake is set firmly. Turn the ignition on.

Now all of the following steps have to be done smoothly. Depress the clutch and shift the transmission into the lowest gear. Hold the clutch down and release the parking brake. If you don't immediately begin to roll down the hill, give yourself a little push with your free foot to get going. When you feel you're at top speed, release the clutch. The mower should start. Go ahead and mow for a while to let the battery charge.

If you have a friend push you instead of rolling down a hill, follow the same basic procedure. Pop the clutch at top speed.

How Do I Keep My Riding Lawn Mower's Battery In Good Shape?

So, we've covered a few ways to get your mower revving when its battery is dead, including how to jumpstart it. But it's best to be able to just turn the key and get going.

Your battery can last longer than three years, maybe more than twice as long, if you take good care of it.

First, keep it on a float charger during the winter. This is probably the single best thing you can do for your mower's battery. Even if your mower starts right up in the spring, it still drained quite a bit during storage. The alternator will charge it right back up, but that deep drain and quick recharge shortens the battery's life.

Cold is also bad for batteries. If you can, store your battery in an area that stays above about 50 degrees. Keep it connected to your float charger no matter what the temperature will be.

Keep your terminals clean. This should be part of your regular maintenance anyway, right along with cleaning under the deck, changing the oil and spark plug, sharpening the blades and cleaning the air filter. Invest in a good terminal cleaner. You don't need anything fancy. Rudman makes a nice cheap one. It's basically a steel-bristled brush designed for battery terminals.


We covered a lot of ground explaining how to jumpstart a riding lawn mower with a car, and answered a couple important questions related to that. Still have more questions? Leave me a comment below and I'll do my best to guide you to your answer.

Ed Kirkland
 

Hi, I'm Ed, and I've been doing lawn work since my mid teen years, picking up jobs here and there mowing and helping with basic landscaping projects. I worked at a couple different lawn care / landscaping companies throughout my college years, and now thanks to the internet I'm able to make a share my knowledge and advice with people about lawn care and landscaping.

Click Here to Leave a Comment Below 1 comments
Pat Lindquist - June 13, 2019

Thanks for the info. One of the better explanations I have read . . . Question though, as you know more about lawnmowers than me (I’m a girl). Had my riding mower on a trickle charger all winter and had no trouble this Spring. Last week, I ran into a piece of rebar sticking out of the ground. (Don’t have a clue how it got there or how I had missed it the half dozen times I had cut grass already.). It stopped the lawnmowercold but started back up and I was able to finish cutting grass. This week however, when I turned the key to start the mower, nothing. No click or anything. Any ideas?

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