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How to jumpstart a lawnmower?

A lawnmower is a machine we use to make our lawns look beautiful. They are best for cutting and shaping your grass quickly. A lot of the bigger lawnmowers use a gas engine and a battery to start the engine. But sometimes, after you want to start your lawnmower, after some time not using it, it will not start. Or you have a lawnmower that is difficult to start, and after some tries, the battery is dead. If this happens quickly and your battery is already years old, it is a good idea to replace it. But to start mowing today, you have to recharge your battery. But charging always takes some time. In that case, jumpstart your mower might be a good option. You can jumpstart with both your car, car battery, or using a special jump starter. But first, you need to find out whether the battery is dead or there is another problem with your lawnmower.

How to jumpstart a lawnmower:

  • Step 1: Check if the battery is really dead or there is another problem why the lawnmower is not starting.
  • Step 2: Accessing the Mower’s battery using jumper cables and a car battery or special jump starter.
  • Alternative A: Connecting a battery charger.
  • Alternative B: Start the lawnmower using a screwdriver or a cable.
(CC BY 2.0) by Ken_Mayer

Steps to jumpstart a lawnmower

We shall provide in-depth details of the steps mentioned above in the section below, like how easy to give a push-start to your lawnmower. Stay tuned to this article, as we are here to get your problem solved without wasting any time.

Step 1: Check if the battery is dead

The first thing you should do is check if the battery is dead. The easiest way is to use a multimeter and measure the voltage on the battery. If you measure 12 Volt, the battery will be fine, and there is another problem with your lawnmower. If you measure a much lower voltage, or even not voltage, it means that the battery is dead. Make sure the cables from the multimeter are connecting correctly with the battery terminals, and that they are not dirty.

If you do not own a multimeter, you could also try to connect a 12-volt lamp to the battery. If the lamp is turning on in full brightness, the battery is fine. If the lamp only slightly lights up or is first bright and quickly dims, the battery is empty.

Step 2. Accessing the mower’s battery using jumper cables and a car battery or jump starter.

When you try to start your shut lawnmower after not using it and find out that it does not start, it can be quite frustrating. You checked the battery, and it seems this is the most probable cause.

Once you are sure that the problem occurs because of a dead battery, you may need some tools like wire brush baking soda and jumper cables in your car or a jump starter to troubleshoot and fix this issue.

Jumpstart step 1: Locate the battery

The battery of a lawnmower is in the hood or under the seat. Check under the seat; if there is not any battery, and then check inside the hood. Open the battery compartment and shut off the mower’s engine before attempting to charge it. It would help if you connected the positive cable of the lawnmower’s battery to the car’s battery’s positive terminal and similarly the negative to the negative.

Jumpstart step 2: Clean the battery terminals

We will check any corrosion on both batteries’ terminals to charge the lawnmower’s battery with the hope car’s battery. Battery corrosion looks like white or green crust. It is unpleasant as well as acidic, so you must put on your gloves. Get a pair of work gloves such as rubber-coated or mechanical gloves. This helps to prevent a shock. The corrosion can also cause the battery to no longer work. We will use baking soda and a wire brush to prevent corrosion. Do wear your gloves before doing this. If you do not see any corrosion, you do not need to clean it. On the other hand, if the battery is corroded or has acid leaking out, you must replace it at once; that battery is of no use and is damaged.

Jumpstart Step 3: Connect the jumper cables and start the lawnmower

Jumper cables have sets of red and black clamps, and one step is used for each battery. Connect the red jumper cable to the positive mower then the car terminal. Please don’t allow them to touch each other. Start the car and connect the black jumper cable to your car’s negative terminal. After it is done, start the lawnmower. If the engine starts and then stops, try again. After leaving the lawnmower engine running for a short while, you can remove the jumper cables in reverse order.

Remark: If you use a special jumpstarter, you have to turn it on before starting. Check the jumpstarter manual for more details.

Additional Concerns:

A primary concern should be your safety while working with the battery:

  • Make sure that both the car or jumpstarter have the same voltage as the lawnmower battery.
  • There is always a slim chance that the lawnmower battery will explode. Yes, the chance is small, but it is best to wear safety goggles.
  • Use leather gloves to protect your hands.
  • Make sure that both the car and the lawnmower are using the parking brake.

Alternative A: Connecting a battery charger

Another method to jumpstart a lawnmower is by connecting a battery charger with a lawnmower battery and charge it. Some chargers even have a special starter mode, where they can supply enough power to start the engine. Always check the voltage of the battery and use a charger with the same voltage rating.

If the charger can be used to directly start the engine, clamp the red cable to the mower’s battery’s positive terminal and the black cable to the negative terminal of the mower’s battery. If your charger has enough power, you can now start the engine. If your charger does not have this feature, you will have to leave it charging for some time. As soon as enough energy is in the battery, you can disconnect the charger and start the engine. There is no need to charge until full if you are in a hurry.

Alternative B: Using a screwdriver especially for riding lawn mower

If you cannot start your riding lawnmower, but you find that the battery still has enough energy, there is the chance that there is something with the starter key. Maybe it was always difficult to start with the key, and now it does not work at all. Do not worry, we will tell you how to jumpstart a riding lawn mower with a screwdriver. This also works if you can not find your key.

Step 1: Start a riding lawn mower with a screwdriver or cable.

By stating a lawnmower with a screwdriver, you should wear gloves. Make sure that you engage the mower’s brake and disengage the cutting blade. Open the mower’s hood and locate the back of the part where you put the key in, the key switch. Sometimes you need to remove additional covers to locate it. The back of the key switch should have two cables running to it.

After you have located the part, understand that depending on the mower, there are two different methods:

Situation 1: This is for models where you only use the key to start, and after the mower has started, you could remove the key. Turning off the engine is usually done with another switch or a lever.

Situation 2: Mowers that need to have the key in the ignition and turned. Similar to a car, you normally turn off the engine by turning the key to the off position.

Check if you see a  and locate a small box hooked at one side of the engine. Apply the bridge mechanism with the help of a screwdriver. There are two connectors present; touch these connectors with the help of a screwdriver. Ultimately the lawnmower will start.

Step 2, Situation 1: A flat head screwdriver can be used to start instead of a key.

After you have located the ignition switch’s back, check if you can see metal from the cable or switch terminals. If this is the case, you can use a screwdriver to shortcircuit those two terminals. This way, you use the screwdriver as an ignition switch. As soon as you make this “short,” you should hear the starter motor trying to start the engine. If the engine is running, you can remove the screwdriver. If you do not see the terminals’ metal, you have to disconnect the two cables and use a wire to connect.

Step 2, Situation 1: Use an electric wire to start instead of a key.

If the key has to stay in the mower to keep it running, like most models starting is slightly more complex. If you check the ignition switch’s back, you find that there are three cables. Two of them need to be connected. One of the cables is connected with the – from the battery (or ground). Sometimes the metal body of the lawnmower is used for this ground lead. If that is the case, the switch will be in a metal panel connected with the other parts of the body, and there will be only two cables going to the back of the switch.

In the case of 3 cables, locate the one connected to the – from the battery. One of the other two leads will be to start the engine, and the other needs to be permanently connected to the – to keep the mower running. If you try both of them to quickly connect with the ground cable (the one you just found out is connected to the – or ground), you will find that one will run the starter engine, and the other one does not seem to do anything. The one that does not seem to do anything needs to be connected to the ground with a short electricity wire/cable. This needs to be connected during the time the lawnmower engine is running. If you disconnect this cable, the engine will stop. With the other cable, you can start the engine by connecting it shortly to the – (or ground) cable.

In the case of 2 cables, you need to do something similar, only you do not have a ground cable, but you need to use a blank part of the lawnmower’s body to connect 1 of the two cables during the time the engine is running. And the other shortly to start the engine.

Remark: make sure that you connect the cables securely so that they will not get loose during the time you are using the lawnmower. You can use duck tape to do this, until you have a more permanent solution.

Frequently asked questions

1. How to know when the lawnmower battery is dead?

Sit on the mower and try to start it. If the lawnmower produces a clicking sound, the lawnmower battery is dead. This dead battery can be charged by the car or with the help of a battery charger. Look for the corrosion. If the battery is corroded, then replace it at once because the corroded battery may no longer work.

2. How to check whether the battery is corroded or not?

The corrosion of the battery looks like a white or green crust. It is unpleasant and acidic. If there is a white or green crust on the battery, it means that the battery is corroded. The corroded batteries don’t work.

3. Why the lawnmower turns over but not starts?

If your lawnmower turns over but is not starting, there might be any other problem that may occur. In this case, check the spark plug and air filter. If it is dirty clean it and then again tighten it. Also, check the carburetor.

4. I lost my lawnmower keys

If you have lost your keys, you can first try to place the screwdriver in the location you normally put in your key, and turn it around gently, just like a key. The lawnmower will probably start.

Additional Method:

If you do not want to use a screwdriver to start the lawnmower, you should install a new ignition switch. Call a mechanic; he will remove the old ignition switch and replace it with the new one. Now you will be able to start it with the help of keys.

Final Remarks

The lawnmower might not start if it is left alone for a longer period. When you take out your lawnmower for work after a long winter, it may require a jumpstart. In this case, you need to troubleshoot the problem effectively so that your lawnmower works smoothly. However, this issue can be fixed without difficulty because it merely needs a jumpstart, explained above in detail. One of the easy solutions is to use another battery and charge it. If the battery is dead, it can be charged with the help of a charger or a car. In case the battery is fine, and you have lost the keys to your riding lawnmower, it can be started with the help of a screwdriver or some electricity wires. On the other hand, if the lawn mower’s battery looks corroded, it needs to be substituted at once because the corroded battery does not work any further.