Restore a Lawn Mower Battery in 3 Easy Steps

Published on: February 4, 2022
Written by Liam Jaxon / Fact-checked by David Rowan

Don’t get intimidated by the title. We are not talking about any professional terms here. Rather, we discussed here some tips and tricks that anyone can follow to fix their dead or weak lawn mower battery. Besides, all these steps are detailed with simplified terms so that you can understand this better and face no problem to follow the instructions. 

restore a lawn mower battery in 3 easy steps

Many people prefer replacing their battery or taking it to the nearest shop to fix it. But a dead lawn mower battery can be fixed at home at zero cost. Besides, it is even faster and easier than taking the whole unit to a local shop. As a bonus, you will also get to know how to maintain a lawnmower battery to make it last longer. 

How Do I Know if My Lawn Mower Battery Is Bad?

Have you left the battery for too long? Then the best way to find out if the battery is bad is to use a multimeter. The usual rating for this kind of battery is more than 12 volts. If the battery is below 5 volts, then it is a bad battery. 

Or is the battery is still attached to the lawnmower, then it is best to turn the key of the lawnmower. If this is a bad battery then you can hear the engine hums, cranks, or clicks even, but won’t start. It is a clear sign of a bad battery as well. 

Steps to Restore Lawn Mower Battery 

A lawnmower battery can be fixed at home with over the counter items. Don’t believe me? Read ahead. Reviving a dead wet cell battery is no big deal if you know how to do it. You can restore a battery without going to the store or handymen, most importantly, without spending a single penny. Here are the steps you need to follow to do it single-handedly. 

Things Needed to Restore a Dead or Weak Lawn Mower Battery

Towels, a flat head screwdriver, 400 or 300 grit sandpaper, baking soda, Epsom salt, distilled water 1 gallon, multimeter, load tester, funnel, and safety gears. 

Safety Rules for Battery Restoration

Use basic safety gears like hand gloves, apron, eyeshield, etc. as this is a wet cell battery, we do not intend to make contact with its content. So, wearing protective gear, full sleeve clothes are a must. Also, make sure you do this whole process to a well-ventilated area, without the reach of children or pets. Once you are on with all the protective measures, simply follow the following steps:

1. Drain and Clean

Mostly lawn mower batteries die before their life is due to sulfate build up in their cells. So, to restore the battery, our first step has to be getting rid of those sulfate build up. To do so we need to clean the outer surface with a wet towel. If the terminals of the battery have got corrosion in them, then only a wet towel will not be enough. Use a corrosion cleaner or sandpaper to clean out that debris. 300 to 400 grit sandpaper is best to use for this. 

Next, after scrubbing the terminals of that battery, use a flat head screwdriver to open up the cell lids. It’s pretty easy, but be careful not to spill the liquid all over the place. This is mainly acidic and can burn your skin and clothes. This is the reason for the safety rules we suggested to follow during this procedure. 

However, now, you have to turn the battery upside down to drain off all the solvent inside. A well-ventilated area is a perfect place to do it. Use a plastic tub to drain the foul liquid. After that mix 40 ounces of baking soda with a glass of distilled water. Once mixed, use this mixture to the whole gallon of distilled water to make a thinner soda and water mixture. 

Use a funnel to pour this soda and water mix into the cells. Fill in the cells to the top and close the lids. Now shake the battery for a minute or two to make sure that the mixture reaches every corner. Now again, drain the solvent from the battery. The baking soda from this solvent miraculously cleans up the battery cells. 

2. Pour Electrolyte

Now your battery is ready to get a new shot of fresh electrolyte. It is sold at home depot and other hardware stores, but you can make it at home cheaper way. Mix 4 ounces of Epsom salt to a gallon of warm distilled water. Mix it well and pour into the battery cells using a funnel. The cells should be filled up to the top, otherwise, it won’t charge up. No need to close the lid as for the next step we need to keep the cells open wide. 

3. Charge and Cycle

Your battery is ready to take a charge. Set it on a low charge or trickle charge mode. Let it charge at 2 amp for 24 hours. Most battery gains life within that time. You can check the improvement with a multimeter and load tester. If the battery shows 12 volts or more, then it is charging all right. 

Now, the load tester will tell if the cranking amp of the battery is fit for use in the lawnmower or not. If the cranking amp is more than 200 amp, then your battery is all good. The preferable cranking amps are different in different batteries. Find the correct amp for your battery on the attached stocker. 

However, when the charge is fully done, disconnect the charger. Now, again, fill the cells with distilled water and wipe out the excess water. Close the lid and use it in the lawnmower, leaving the engine on to start the battery cycle. 

If the battery’s cranking amp is weak, then at that moment you have to stop charging it. Set the battery in the car and leave the car lights open. Again, test the volts and cranking amps of the battery. Not good? Then try using a new or different charger for 24 hours. After that, the battery will give a good result. Otherwise, you can count the battery totally useless. 

Quick Solutions

As soon as the winter season ends, we start getting calls and messages about fixing lawnmower batteries or inspecting them. However, these are quite an easy task and once you understand the pattern, you will never need to go to experts. Here are some questions I mostly face, but easy to deal with at home. 

What Keeps Draining Your Lawn Mower Battery?

Your battery might have a loose connection. Often, the loose connection is the main culprit for draining the battery life. It works harder than regular, hence, the power drains. To solve the problem simply check, clean, and tighten all the cables that are attached to the battery posts. Another thing that can cause this problem if your battery case has a crack on it. Then this problem needs a professional involvement or replacement of the battery itself. 

How to Make a Lawn Mower Battery Last Longer? 

Technically, lawn mower batteries are hard to kill or cause damage to. They just behave weirdly when not taken care of properly. Just keep the wet battery dry and clean all year long. Before winter, when your lawnmower will be idle, disconnect the battery from it. Pick the battery from the lawnmower and keep it in a safe place where it won’t freeze at all. This is the secret of long life for lawn mower battery. 

How Many Times the Lawn Mower Battery Needs to be Charged?

Once in a month, when the lawnmower is not in use. Put the battery on the charger for 8 to 10 hrs, until it is fully charged. Then, you can bring it out before winter to store in a safe place. The next time it needs a full charge is right before using the lawnmower. Keeping a wet cell battery functioning is not much of a headache now. 

Final Verdict

Wet cell batteries are designed to last for long long years. So, low battery power or dead batteries can be easily treated. The main motto is, if you take care of these batteries on a regular basis, they rarely go bad or die early. So, keep an eye on the battery cells and their performance. If you see any change in its functioning pattern or suspect its performance, well, now you already know how to fix this, right? 

If all the methods I described here fail to restore your battery, then the professionals may be your last hope or maybe you really need a replacement battery. However, there is no harm in trying these tips before actually giving up on them. 

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About This Writer

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Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

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