How to Change a Lawnmower Battery?


Gas-powered lawnmowers of any type with electric starters need a battery to provide energy for starting the engine. The battery also provides energy for any other electrical functions, such as headlights in a riding mower. Most Lawnmower batteries are rechargeable and can be used for long periods. But after several years of performance, a battery loses its ability to hold and store charge, which makes it useless. In this case, it has to be removed and replaced.

How to Change a Lawnmower Battery:

  1. Check the current battery type and get a replacement
  2. Disconnect the old battery
  3. Remove the old battery
  4. Install the new battery
  5. Connect the new battery

You can always hire a mechanic to change a lawnmower battery for you, but changing it yourself will save you time and money. The process of changing a lawnmower battery is fairly simple and the same as changing a car battery. It is important to note that lawnmower batteries are specific to the type and model of mowers. So, you should make sure to choose the correct type of battery for your lawnmower. Information about the type of battery can be found in the owner’s manual.

These five operations are divided into several steps. Following those steps will make the battery changing process simpler for you and help you make sure that none of the connecting wires, battery terminals, etc., are damaged during the changing process.

Let’s get into the details of the steps for changing a lawnmower battery.

Steps for Changing a Lawnmower Battery:

Follow these easy steps to change your lawnmower’s battery yourself:

● Step 1: Turn the Lawnmower completely off

Park your lawnmower on a clear, level surface. Make sure that the mower starting key is in the off position. If not, turn it off and remove the key. Disconnect the spark plug wire, allow the blades and all other moving parts to stop, and give the mower some time to cool down. If you are working on a riding lawnmower, there are additional things to do. Disengage the blade, engage the parking brake, and make sure that the transmission is in neutral.

● Step 2: Locate the battery compartment

The next step is to locate the battery compartment in your lawnmower. For riding lawnmowers, the battery compartment is usually under the seat or the hood. For push mowers with electric starters, the battery is generally located at the back or top or on the deck in a black box near the handle.

● Step 3: Safety first

Once you have located the battery compartment, put on safety goggles and gloves for protection from battery acid. Make a solution of 1 tsp of baking soda in a cup of water in a disposable cup. Mix thoroughly with a spoon to dissolve the baking soda.

● Step 4: Disconnect the old battery

The next step is to disconnect the old battery. The battery’s negative terminal has a “-” sign on it, and the black battery cable is connected to it. The battery’s positive terminal has a “+” sign, and the red battery cable is connected to it. Loosen both the negative and positive terminals of the battery using an adjustable wrench by turning it counterclockwise. Once the terminals are loosened, pull and remove each battery cable off the old battery.

● Step 5: Remove the old battery

Pick the old battery up from the center handle removing it from the battery box. Put the old battery aside.

Clean the battery compartment or box with a rag dipped in 50-50 solution of baking soda in water. Use the dry side of the rag to dry the compartment.

● Step 6: Take care of corroded terminals

Often, there is corrosion on the battery terminals that binds the battery cables to the terminals. Pour the baking soda mixture that you prepared on the battery terminals to dissolve the corrosion.

If your lawnmower has a battery-stabilizing bracket, you need to loosen it and push it to one side. To do this, insert a flat-head screwdriver in the bracket and rotate the screwdriver counterclockwise to loosen the screw and push the bracket on one side.

● Step 7: Clean the terminal ends

Make sure the terminal ends of the battery cables are clean. For this, insert the battery terminal cleaner’s pointed end into each battery cable and turn the cleaner in circles to remove corrosion and dirt. The corrosion badly affects battery performance. Clean both cables until the inside of both circles is clean and shiny. Use a shop towel to wipe off the excess metal shavings, if there are any.

● Step 8: Get the correct replacement battery

Ensure that the new battery matches the old one in weight, dimensions, capacity, voltage, and terminal placement.

Place the new lawnmower battery in the battery compartment. To prevent the battery terminals of the new battery from developing corrosion, apply a thick coating of petroleum jelly to the terminals.

● Step 9: Connect the new battery

Connect the red battery cable with the new battery’s positive terminal and tighten it with an adjustable screw. Do the same procedure for the negative terminal and the black cable.

● Step 10: Make sure the battery is fixed correctly

If your model has a battery bracket, put it back and tighten the screws clockwise to hold the bracket in place.

● Step 11: Dispose of the old battery

Batteries are toxic, and so the old battery must be disposed of properly. For this reason, take your old battery to a car service station or recycling center, or an auto parts store.

● Step 12: You’re ready to start your Lawnmower

Now, start the mower. If it starts in the normal fashion, the new battery was installed correctly and is good to go.

Tips and Warnings Related to Battery Changing:

● Tips:

  • Check the battery type: As mentioned earlier, battery types are specific to mowers’ type and model. For best results in performance, use the battery most suited to your mower. Information about the battery can be found in the owner’s manual. When replacing the battery, it’s best if the new battery has the same voltage as replaced. The voltage rating is listed on top of a battery.
  • Corrosion: Check your battery for corrosion at least once a month.
  • Battery maintenance: Consult the user manual for info about the proper charging and maintenance of the battery. Ensure proper charging and maintenance for best performance and longer battery life.
  • Battery holder: Ensure that the battery holder is clean. Remove corrosion and debris from the holder and keep it dry if the holder is metal, sand, and paints, the rust spots because battery fumes can accelerate rusting.

● Warnings:

  • Fight corrosion: Don’t let any mixture or water get into battery cells when rinsing off corrosion.
  • No force: If you pull the cables off forcefully, the connecting terminal can be popped off. So, pull the cables gently.
  • Short circuit: When removing and replacing battery cables, do not touch the adjustable wrench to any other metallic part of the lawnmower. Otherwise, sparks may fly and cause battery discharge.

Testing a Lawnmower Battery:

One reason for a lawnmower not starting can be the battery not holding a charge. With basic knowledge and the right tools, this problem can be tested and fixed.

● Step 1: Locate the battery

Locate the battery of your mower and clean it before testing. Use a flat-head screwdriver to clean off any corrosion or debris on top of the battery. This will ensure a proper connection between the battery and the multimeter. Identify the type of the battery and the voltage that it takes.

● Step 2: Check the battery type

6-V and 12-V are common battery voltages. Most lawnmower batteries are 6-V batteries. Set the multimeter to the correct voltage of your battery. A multimeter is a measuring device that can be used in the testing process. Set the multimeter to the correct AC/DC settings if it has any. For this, you can consult the owner’s manual. Most mowers use a 200-V DC setting. The battery charger should also be set to the correct battery voltage.

● Step 3: Remove the battery cables

After that, remove the battery cables and check the terminals for corrosion and debris. Clean the terminals. Connect the red multimeter cable to the positive terminal and the black multimeter cable to the negative terminal and read the multimeter reading. If the voltage is correct, examine all the fuses and connections on the lawnmower. If it’s not correct, check the battery’s water level.

● Step 4: Check the water level

Remove the cap using a flat-head screwdriver and examine the water level (depending on the battery type). If it is low, add distilled water until it rises to the proper level. Put the cap back on and test with the multimeter again. If the problem was due to low water level only, it must be solved now, and the multimeter will show the correct voltage.  

● Step 5: Check the fuse

If the multimeter still does not show the correct voltage, check the fuse next to the battery. Fuses often burn times and cause lawnmowers not to start. Remove and replace the fuel, and the problem will be solved.

Related Questions:

● Can a lawnmower battery shock you?

Yes. Contact with water while charging the battery may lead to an electric shock leading to injury. Never touch the two battery terminals at the same time because that will cause a shock too. Avoid contact with water while operating your mower to stay safe.

● Is changing a lawnmower battery just like changing a car battery?

Yes. Changing a lawnmower battery is similar to changing the battery of a car. If you know how to change a car battery, you can change a lawnmower battery, and vice versa.

Final Remarks:

A rechargeable lawnmower battery can easily serve for up to three years, after which it loses its ability to hold a charge and becomes useless. In this case, it must be replaced. Changing a lawnmower battery is a simple process. Following the steps mentioned above, you can easily change your lawnmower battery without having to go to a repair shop or hiring a mechanic. It will save you both time and money. To ensure maximum performance and longer battery life, clean the battery terminals regularly, and keep the water correct.

Recent Posts