Can You Jumpstart a Lawnmower With a Car?

Flat batteries are one of the most common issues people face, especially during the off-season.

An easy solution to this problem is jumpstarting your lawnmower battery. But can you jumpstart a lawnmower with a car?

Yes, you can. You can jumpstart your lawnmower by attaching the lawnmower’s battery with the car battery with the help of jumper cables. Attach the poles correctly with the positive first followed by the negative pole and then turn the ignition switch to jumpstart the mower.

Jumpstarting the lawnmower isn’t as easy as it seems. This extensive guide will explain to you step by step how to jumpstart a lawnmower with a car.

Here are things you will need to jumpstart your mower:

Table of Contents

Checking the Battery

When your lawn mower battery dies, before attempting to jumpstart it with a car’s battery, ensuring the battery is safe and secure is very important.

Leaking battery acid can burn the eyes, so wearing gloves and eye protection is a must if the battery is hot. In addition, make sure the terminals are safe and unharmed. Arcing can occur if the terminals are broken or loose, stopping electricity from hitting the starter.

Cleaning the Battery

The second crucial step is to clean your battery. Dirty, corroded, or lose terminals create a barrier to the transfer of power from the battery to your starter, preventing the alternator from recharging the battery. This is one of the major causes of lawn mower battery dying.

If your battery is dusty, clean them before you start with the process.

To begin, put on your protective eyewear and gloves. On the terminals and battery posts, it will show as a white crusty accumulation. Sprinkle some baking soda on the terminals and a little water on top to neutralize the acid and eliminate the corrosion.

To clean the surface, you need to remove the terminals and completely clean the area around the poles and terminals with a wire brush.

Here is a tip for you: To further prevent corrosion, apply a layer of petroleum jelly.

Checking the terminals

Battery connections often come loose because of the Mower’s vibration. It is always better to tighten the terminals and start the Mower again if the loose connections were the problem.

However, if the battery terminals are badly damaged or corroded, you have no choice but to replace them.

In some cases, you may notice the cables being extremely hot; this indicates high resistance. Replacing them with strong standard leads and terminals instead can increase your battery life.

Jumping your Mower’s battery

The jump/boost start process is very straightforward. You would need a series of booster cables. If you need boosters, invest in a high-quality package. Poor-quality cables will struggle to make a decent connection, making the task even more complicated.

We recommend the Cartman Booster Cable. They deliver great performance, are made up of premium PVC, resistant to extreme temperatures, and above all, it comes with a 1-year warranty.

The positive and negative battery poles are usually color-coded, but they are often marked Red (+) for positive and Black (-) for negative. For convenience, park your car next to the Mower and pop the hood. Most cars have a plastic shield, so you need to remove it.

Then simply match the lead colors to the battery colors. Always begin with the Red (+) jump lead. You need to attach both the positive poles of each battery with the cable and then move onto the Black(-) lead.

Now turn your Mower on and remove the cables, black first followed by the Red. And that’s it. This should jumpstart your lawnmower.

Jump Start Doesn’t Work?

Sometimes jumpstarting the Mower’s battery doesn’t work despite following all the steps carefully. There are many reasons for it. Here are a few of the main reasons:

Mower Click Once

If you tried to jumpstart your Mower and even the battery was fine, you might have a starter solenoid fault. These guys cause a lot of problems, so it’s a strong possibility that you have a fault in the solenoid.

The solenoid acts as a large relay. A 12 volt supply from the ignition switch to the solenoid triggers it as you turn the key to power the Mower. The solenoids’ purpose is to attach the battery to the starter motor and crank the engine on for as long as you keep the key in the ignition.

In most cases, replacing the solenoid is an ideal decision. Not only are they cheap but also easy to install and fit.

We highly recommend Koauto New 532192507 Starter Solenoid (Amazon). The solenoid is secure, stable, and durable, so it is a great replacement option if you run into faulty solenoid trouble.

Mower Doesn’t Click

If you are wondering why your Mower didn’t start, not even a click. There are various reasons for it: bad battery connections to a faulty ignition switch or even the possibility of the main fuse blown. The reasons can vary, and it is important to diagnose the correct problem.

Main Fuse Blown

If the battery is fully charged, but the Mower still won’t start or even click, check the main fuse. There might be a possibility that the main fuse has blown.

Some mowers will use a blade-type fuse, and others will use a bottle-type fuse. You can find fuse under the seat or hood, behind or near the fuel tank, or in the control module.

When the fuse blows, the control is lost. However, it is very easy to change the fuse. It is essential to replace the fuse with one that has the same or appropriate amp level. If you see the fuse is blowing repeatedly, either the fuse level is too low or short-to-ground wiring is causing the fuse to blow.

Ignition Switch Issue

Ignition switches are an essential component of the ignition mechanism, and weak connections can lead to a number of issues. Ignition switches are responsible for transmitting commands to the control module, which then starts the engine.

If the Mower doesn’t have a control module, the safety sensors are connected inline to the ignition switch, which means that any open sensor will cause an open circuit in the ignition switch. An open circuit is an incomplete circuit, so no current passes through the circuit. Hence, the Mower fails to jumpstart.

Wiring is different for each Mower’s ignition system, so the process can vary. Have a helper sit on the Mower and keep trying to start it while you can see the solution. This can help diagnose the problem. Also, check for damaged or loose wiring.

We highly recommend getting an expert if you feel like the Mower has an ignition switch issue.

Testing Battery

Starting a lawn tractor mower requires a solid, healthy battery. A mower engine will only generate enough energy for the spark plug to light if it spins quickly enough, at least 350rpm. If your mower cranks but won’t start, you might want to test your battery health.

Checking for a full 12.65 volts on a battery at rest is a decent way to get an estimate of how charged it is, but it’s not a guarantee that it’s fully charged. The battery must be loaded and overworked to search for faults.

An easy way is by using a volt meter. Set the voltmeter to 20 volts DC to check the battery quickly and easily.

If you don’t have a voltmeter, we highly suggest grabbing one. AstroAI Digital Multimeter (Amazon) is ideal for measuring voltage, current, resistance, capacitance, and frequencies. With easy-to-use settings, it is by far the most outstanding multimeter for everyday use.

Frequently Asked Questions

Q) How many amp batteries should I get for my Mower?

The heavier your mower motor is, the more amps it would take to turn it on. The battery’s output is extremely critical. When starting a lawnmower, a single-cylinder starter motor can pull 80 to 100 amps. The larger the draw, the higher the mechanical resistance in the engine.

Q) How to charge a mower battery?

You’ll need a battery charger to charge the battery in your Mower. The battery does not need to be removed from the Mower, but the black negative (-) cable terminal attachment must be removed. Then placing the positive with the positive and black negative with the charger’s negative should start charging the battery.

Q) What is a smart charger?

Smart chargers are programmed with several automatic measures and variations to ensure that the battery achieves the highest possible charge. To get the best output from a battery, a standard smart charger may have up to 8 or 9 distinct stages.

Q) Can a completely dead battery be recharged?

A dead battery can be recharged, and depending on the situation, it’s normally a simple fix. You first need to jumpstart your battery and then charge it with a dedicated battery charger.