Skip to Content

How to Remove a Lawnmower battery, step by step

Lawnmowers can be categorized into two major categories; gas lawnmowers and electric lawnmowers. Both serve the same purpose and also work in almost identical. The only difference is their power source. The first one works on gas, and the latter runs on electric energy. Even though some gas mowers work on gas, they still need batteries to start the engine. It provides the electric energy for the starter motor and the ignition system. Suppose the battery lacks charge, the engine won’t start. If the battery is bad, it needs to be replaced.

Knowing how to replace your lawnmower’s battery will save you time and money. Over an extended period of use, lawnmower batteries deteriorate and lose their ability to give enough power. They can only be charged and discharged a certain amount of cycles before they need to be replaced. The battery-changing process is quite simple. It involves the removal of the old dead battery and the installation of a new one. This blog post will guide you through the replacement process step by step.

How to remove a lawnmower’s battery, step by step:

  • Step 1: Make the lawnmower ready and charge the new battery
  • Step 2: Locate the current battery. Remove the hood or seat depending upon the type and lawnmower brand
  • Step 3: Disconnect the battery by disconnecting the wires from both of its terminals.
  • Step 4: Remove any bars or hold down rods keeping the battery at its place.
  • Step 5: Remove the old battery
  • Step 6: Place the new battery in place of the old one
  • Step 7: Connect the new battery and put back all bars and hold-down rods to keep the battery in its place.
  • Step 8: Start the lawnmower to test the battery

Before starting the whole process, be sure to get all the necessary tools and follow all the safety precautions.

Guide on Battery Removal and Reinstallation/Installation of New Battery:

This blog post targets the removal and replacement of batteries used in a riding gas lawnmower or self-driving gas lawnmower with an electric starter. And for a smaller cordless lawnmower that uses rechargeable batteries that can be removed. If you have a big riding electric lawnmower uses a lot of batteries  strored in the lawnmower frame. These are not meant to remove and replace. Working on those batteries should be done by a professional. We will go through the step-by-step battery removal and installation processes for both:

Method 1: A Gas-Lawnmower

● Needed tools to remove the lawnmower battery:

You will need a screwdriver, a wrench, battery acid, baking soda, and protective gear like safety gloves and safety goggles.  

● Step 1. Prepare the Lawnmower:

Place the lawnmower in a well-lit environment, preferable on a flat surface. If you have a slopy driveway, get some wooden wedges and place them under the mower’s wheels. Placing the wedges will stop the lawnmower from rolling while you are working on it. Also, use the parking breaks to ensure the lawnmower does not move.

● Step 2. Locate the battery:

Different mowers have their battery installed in different places. A self-propelling lawnmower battery is located near the handle in a black box. In the case of a riding lawnmower, the battery is located under the seat or in the hood. Open the hood or seat to expose the battery. If you have problems locating the battery, please consult your user manual for more information.

● Step 3. Disconnect the battery:

Ensure the contact from the mower is off and the key is removed. Disconnect the two battery cables. Check both terminals and the battery connectors. If they look dirty, you have to clean them later.

● Step 4. Remove bars or hold down rods:

Usually, there are a couple of bars or hold-down rods keeping the battery from moving. To get the battery from the mower, these bars or rods have to be removed first. You’ll need a wrench to unbolt them. With the bolts removed, take these bars out, and the battery is free to be removed.

● Step 5. Remove the battery:

Please remove the battery, carefully picking it from its top. If you plan to use the battery again, this is the time to clean it. Use a battery checker to see if the condition of the battery is still ok. Recharge the battery to make sure it is ready to be used. If you replace the battery, make sure that the replacement battery is also fully charged. Check that the dimensions, both size, and power ratings are the same as the original battery.

● Step 6. Reinstall the battery/install the new battery:

If the battery is ready to be installed, place it in the battery compartment. Use a coating of petroleum jelly on the battery terminals to avoid corrosion.

● Step 7. Reinstall the electrical connections and the hold-down bars:

After placing the battery, reinstall both the battery cables. Make sure they are clean and do not have dirt or corrosion on them. Connect the red wire to the positive terminal and the black one to the negative terminal. Reinstall the hold-down bars to lock the new battery, and make sure all the screws are tight.

● Step 8. Test the battery:

After the replacement has been finished, it is time to start the engine. Use the key or button to start the lawnmower engine as you normally would do. If you did all things right, the mower would start and run perfectly. If it does not start, check the battery cables again. Make sure they are connected the correct way. If still nothing happens, check the battery with a multimeter of battery checker. If the battery is ok, there is another problem that needs to be diagnosed. Please see one of the other articles for more information.

Method # 2: An Electric-Lawnmower:

Now we will discuss the process for an electric-lawnmower. Removing the batteries is much easier. The lawnmower is designed to have its batteries removed and added.

-Step # 1 Charge the new battery:

Always charge the replacement battery fully before installing it. Check the user manual on how to use the charger for your specific lawnmower. The charger will have a light that shows the charging state of the battery. When the battery is fully charged and ready to be used for most chargers, the led will turn from red to green. Charging the battery can take up to 15 hours on average. If you have a fast charger, this will go much faster. Some newer models can charge the battery up to 80% in less than an hour. When you finished charging, and the charger is empty, unplug the charger from the mains outlet.

If you have a modern charger, it will have a trickly charger option. This means that you can keep the battery in the charger at all times. The charger knows when the battery is full, and it changes to a special mode to keep the battery in an optimal condition. During charging, keep the battery in a dry place.

-Step # 2 Remove the old battery:

Please remove the battery lock on your mower to remove its battery box’s latches. Please pick up the battery from its top.

-Step # 3 Install the new battery:

Add the replacement battery in the lawnmower and lock it. Locking is important to ensure that the battery does not get loose during mowing. How to lock it depends greatly on the type and mower brand. Check the user manual for more details.

-Step # 4 Test the mower:

After replacing the battery, it is time to start the mower. Start your machine as you normally would normally do. If you did all things right, the mower should work perfectly.

How to Maintain a Lawnmower’s Battery:

An average homeowner uses his/her mower a couple of times per month. Most of the time, a lawnmower sits idle and has nothing to do. To keep a good functioning lawnmower battery, there are a few things you can do:

  • Charger: Use the battery and charger included in the box by the manufacturer, as they work well with each other.
  • Storage: Store batteries away from metal and moisture.
  • Free of oil and grease: Keep the battery oil and grease-free.
  • Stop when hot: Stop using the mower or charging the battery if it gets too hot.
  • Keep the terminals clean: Protect battery terminals at all costs. Apply petroleum jelly at the terminals to protect them from corrosion.
  • Fire: Keep the battery as far away from heat and fire as you can.
  • Recycle: Never throw away an old battery. Recycle it.
  • Use safely: Don’t try to bypass any safety devices to change the voltage at which a battery charges.
  • Cold: If you live in a cold region, it is necessary to remove the battery before storing it.

No matter how hard you try to maintain your battery, a lawn mower’s battery will lose its efficiency. Usually, it takes a long time, so there is no need to worry about dead batteries. If you used to get 120 minutes of mow time from a full charge and now get 50, it is time to invest in a new battery. 

Older batteries become more resistive and have to work harder to provide the same amount of power. A fully charged battery will slowly drain even if it is not plugged in. However, the discharge takes place gradually. So if you’ve left a fully charged battery in the garage, it’s not going to be dead in a few weeks. Use a trickle charger to keep a battery fully charged in a safe way. If you do not have one, charge it a couple of times during the winter period.

Final Remarks:

Replacing a lawnmower battery is an easy task. Make sure you follow the steps, including the safety precautions. During the winter, batteries will slowly discharge. Use a trickle charger or recharge them a couple of times so you will have full batteries in the spring. Batteries do not have an endless life, but taking good care will extend it.