Riding mower battery bolts. Lawn Mower Won’t Turn Over with a New Battery | How to Troubleshoot

What Size Are Battery Bolts?

Battery bolts hold your battery in place, and having the right size of any bolt is essential because the wrong size of battery bolt can cause problems for your battery and your vehicle.

Having the right size bolt ensures that you can tighten your car’s components properly. Ever wondered what size are your battery bolts? We have asked experts what sizes can battery bolts come in. Here is what we got from them.

The most common battery bolt will have a nut of around 10 millimeters or 0.4 inches, a bolt length of 1.24 inches, and a bolt thread size of 5/16 inches. Battery bolts may also come in different sizes, such as 8 millimeters (0.3 inches), 11 millimeters (0.43 inches), 12 millimeters (0.47 inches), and 13 millimeters (0.5 inches).

Having the right bolt size will help avoid connection problems between your vehicle and your battery. Also, you may damage your battery if you put a bolt that is too big or long for it. If you’re unsure what bolt size you need, it’s best to consult or bring your battery to a mechanic. For more information about car batteries, keep reading below.

Lawn Tractor Clicks But Won’t Start! Easy Fix!

Does The Size Of The Battery Matter

Yes, the size of your battery matters. Having the right size battery helps your car start and run in its optimal condition.

While having a battery that is too small may not give enough power to a larger car. Your car should have a battery that has the right amount of power to supply its electronics; having too little power may ruin some electronics.

Also, if you have a battery that is too big for your car, it won’t fit properly on the battery holder, and because of its bigger size, it may touch your car’s metal hood causing short circuits or even fires.

However, you can use a smaller battery, but this must only be used for a short period of time or in an emergency. Note that this is not advisable to do.

Can A Car Run Without A Battery

Yes, your car can run without a battery in it. Your vehicle will still idle and drive even if you don’t have a battery in it because your alternator is still producing electricity for your car, but you can not start a car without a battery.

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Even if your alternator keeps your car alive despite not having a battery in it, the alternator still needs to have a battery so that it can properly distribute the right amount of voltage.

Without the car battery, the alternator will push out different amounts of currents when your car is at different RPMs. You will also experience a lot of surging when you don’t have a battery.

There may be a few reasons why you would be running a car without a battery, such as needing to move the vehicle somewhere else or testing its electronics.

You can still drive your vehicle for a short distance, but you will still need a battery to actuate all of its circuits to start up the actual engine.

It is also not a good idea to drive your car without a battery on a public road, if your vehicle suddenly stalls, you may cause an accident.

Does Idling Charge Your Battery

Yes, idling your car will charge your battery. Your battery is charging because of the alternator.

An alternator is a component that converts mechanical energy from your vehicle engine into electricity. Your car’s battery is mainly there to help start up your vehicle and keep the electronic components of your vehicle running while the car is off.

The alternator is the component that helps power your vehicle when your car is on. When your car’s on, the alternator provides all the electricity your car needs, and at the same time, it charges your battery.

An alternator is a device that is driven off the crankshaft by a belt that spins the rotor located inside the alternator.

Inside the alternator, there are a series of magnets that have alternating poles to them, and surrounding these magnets are a lot of copper wires. When magnets pass over a conductive wire, it is able to produce an electric current.

With your alternator having multiple magnets and a lot of wires surrounding them, it is able to produce a lot of electrical power for your car.

So if your vehicle is having a hard time starting or stalls a lot, this may be caused by a faulty alternator forcing your vehicle to drain your battery.

How Long Can A Car Sit Before The Battery Goes Dead

If you haven’t started your car in a while, your battery could run out of electricity.

A new battery can typically last for three months before it gets fully discharged, but there are a lot of factors that can speed this up, such as having an old battery, a newer car model, and harsh weather conditions.

An old battery will drain much faster since it may be too worn or worked.

While newer car models will drain your battery much faster because of all the electronics that come with the car, features such as the car’s Bluetooth, clock, security system, and many more.

Hotter temperatures can also affect your car’s battery since the heat could evaporate the battery’s fluid.

Mower not starting, Just Clicks? How to diagnose & Please read video description.

To avoid your battery from completely draining, you should start your car and leave it running for a while. Starting your vehicle once in a while will give the alternator a bit of time to recharge your battery.

But if your car won’t turn on, you might be too late, and you will have to jump-start your vehicle or get a new battery.

Can A Completely Dead Battery Be Recharged

Yes, you can recharge a completely dead battery. But you cant use a battery charger; you’ll need to jump-start the dead battery to give it enough power to start on its own.

You can use another vehicle to jump your dead car battery. From there, the alternator will be the one that will charge it till it’s at full capacity.

It is a good idea to check your battery first if it’s in good functioning order before jump-starting.

Check your battery manufacture date; a car battery will last around five years of regular use. As the car’s battery gets older, the higher the chance it will fail or drain quicker.

You should also check your car battery for any corrosion. Corrosion is a sign that there is going to be a battery draw, and it may be the main cause of why your battery may have drained all its power.

Note that if you’re going to jump your dead battery using another vehicle, you should not fully charge it but instead charge it for a short while to give it just enough power to turn on the engine of the car and run on its own.


Finding the right battery bolt size is important since this helps hold the wires that power your vehicle to the battery.

Having a loose connection can result in your car not wanting to start. If you’re unsure of what bolt to use, consult a mechanic to find the right fit.

When dealing with a completely dead battery, you can use another car to jump it. Doing this will help bring the dead battery to life, and you’ll be able to start the vehicle from there.

Just make sure that you don’t fully charge the dead battery using the other vehicle. You just need enough power to be able to start the vehicle of the dead battery.

For more automotive topics and tips, check out the following posts.

Lawn Mower Won’t Turn Over with a New Battery | How to Troubleshoot

Imagine a situation where you just bought a new battery to fix your lawn mower turns over failure. But even after installing the new battery, your mower won’t turn over. Isn’t it one of the most frustrating situations to handle in the middle of your working on your lawn? The question is, what might go wrong, and how else can you fix such issue?

First, look for dirty connections and clean the battery posts. Then, tighten the terminals and bolts. Adjust the wrenches. Next, get rid of metal bolts and plastic nuts. Check the Starter, external Solenoid Relay to take necessary actions as required.

Thus, read this article till the end and learn how to troubleshoot a lawn mower won’t turn over with new battery.

What Causes the Problem?

In general, most lawn mower or tractor users replace their old internal battery with a new one as soon they notice the turn over difficulty or failure.

Since weak, severely corroded, or dead battery mostly causes a lawn mower to encounter similar issues, this fixing idea pretty much works in most cases.

But in some cases, users notice that their mower won’t turn over like they are supposed to even after installing a brand-new battery.

This commotion mainly occurs due to our negligence during the battery replacement, where we sometimes only change the battery while don’t give importance to checking the surrounding areas or elements.

Because the same problem can occur even after you put a new battery due to corroded battery posts, loose connecting terminals, or bolts.

A similar situation will arise due to a faulty starter, external solenoid, or defective relay.

Steps to troubleshoot a lawn mower that won’t turn over with new battery:

According to most lawn mower users and even mechanical experts, it’s a pretty common issue that users often experience while using their mowers.

In general, whenever people encounter mower turnover difficulty, their initial guess to the possible battery or battery connection failure to cause such a commotion.

However, the battery is not the only component of a riding lawn mower that can cause such issues, and there are other possible reasons to cause a similar problem.

The good news is that several fixing tricks and ideas are available online, but all ideas might not be reliable and effective for your lawn mower.

That’s why I am going to explain a quick, easy, and cost-effective way of troubleshooting your lawn mower that won’t turn over with a new battery:

Things required to troubleshoot the lawn mower won’t turn over with new battery:

Have a look at the checklist of the required tools and materials for this particular troubleshooting task:

Tools Materials
Adjusted Wrench Starter replacement kit (if needed)
Standard Mechanical Tool Box Solenoid (if needed)
Voltmeter Relay (if needed)
1/4”-20 stainless steel hardware Battery terminals (if needed)
Safety Goggles Gloves Bolts nuts (if needed)

Step 1- Look for Dirty Connection:

Even if you have put a new battery, there are a few things that you should look at, and checking the current condition of the battery connections is one of them.

Because most people overlook inspecting there and eventually, these dirty battery connections cause such commotions.

First, check the connections and use some sandpaper to clean all the crud out of these battery posts.

Step 2- Tighten the Terminals as well as bolts Adjust the Wrenches:

The mower engine vibrates while you are using the lawn mower and this vibration transfers to the rest of the vehicle’s internal components.

Over time these little connections become loose.

That pretty much happens with every lawn mower as the mower gets older.

Remember, the battery terminals should be tight enough.

While you are still working in that area, make sure the connecting bolts are also tightened enough.

Also, do not forget to adjust the wrenches there. Take proper precautions before tightening these wrenches.

Otherwise, you can use wrenches and tie knees up but avoid cross touch them at the same time.

Now turn the key and see whether the engine is starting or not.

Tips: While working on adjusting the wrenches, remember not to touch anything that is going to connect the positive and negative.

Step 3- Get rid of Metal Bolts Plastic Nuts:

Another thing that you should consider is changing those metal bolts with stainless bolts because stainless steel won’t rust or corrode and will help keep the corrosion down.

Next, if you see the plastic wing nuts on your mower battery, better to get rid of that plastic stuff and replace them with 1/4”-20 stainless steel hardware. Tighten all the bolts and nuts securely.

Step 4- Checking the Starter, external Solenoid, or Relay:

If you have already inspected the earlier mentioned areas and all are good in shape, you should check whether the starter external solenoid or relay has any issues.

First, use a voltmeter and connect it to the battery. Then, check the voltage reading while trying to turn the starter on.

If you are new, you can follow the easy three steps mentioned and explained in the How to Test a Starter Solenoid article.

The screen should show a reading result between 9.5 and 10volts while the engine is cranking.

If you see lower reading than mentioned, it means the starter has turned bad, and you need to replace the Starter.

If your lawn mower has an external solenoid or relay, you should also verify that the solenoid is mounted securely to the frame as it requires a good frame ground.

Follow the instruction provided in the 3 Ways to Test a Relay to investigate your lawn mower relay and if it looks bad, replace it.

In case the solenoid condition seems too damaged, you can follow the instruction provided in this DIY fixing video.

After you have completed all the inspection and fixing tasks, check your mower whether it works or not.

If it still is not working, better to contact the nearest dealership or servicing workshop.

Undertaking such troubleshooting tasks can be hazardous if you do not have enough expertise. Therefore, always remember to read your lawn mower’s instructions manual before operating, servicing, or troubleshooting it.

Frequently Asked Questions

What causes a lawn mower not to turn over?

Your lawn mower might not turn over due to old or contaminated gas. It can also fail to turn over due to a loose, disconnected, or dirty spark plug and air filter.

Why does nothing happen when I turn the key on my mower?

If you ever notice that your lawn mower doesn’t respond when you turn the key, it can be due to various things. It can be because of a faulty battery, solenoid posts, fuse, ignition switch, coil, brake, and blade switch.

What causes a lawn mower starter to not engage?

A broken, corroded, or dead battery can cause a lawn mower’s starter failure. Even it can be an issue with the charging system. So, whenever you notice your mower starter is not engaging, check the battery and charging system first.

Is it possible to jump-start a lawn mower with a car?

Yes, it is possible. If your lawn mower support or feature a 12-voltage battery, you can jump-start it with a car. But if your mower has a 6-voltage battery, you cannot jump-start it with the car or portable jump-starter.

Final Verdict

Often lawn mower users complain that their mower won’t turn over even though they have just installed a brand-new battery to get rid of that problem.

The main fact is that it is not always the internal battery’s fault and before you plan on purchasing a new battery wait a moment to investigate the areas described in today’s article. Remember, you can only get the best result if you thoroughly follow all the instructions to troubleshoot a lawn mower that won’t turn over with new battery.


Symptoms of a Bad Lawn Mower Battery: Hard To Miss Signs

If you are curious about the symptoms of a bad lawn mower battery, the nyou are among the thousands of gardeners who have this question in their minds. The good news is that most symptoms are hard to miss, such as clicking noises and rotten eggs smell.

In this complete guide, we will discuss all the symptoms that indicate that your battery might be struggling. Carry on reading because we will also discuss changing the electrolyte fluid in the battery to make it last longer.

  • What Are the Symptoms of Your Lawn Mower Battery Going Bad?
  • – The Engine Won’t Start
  • – Produces Clicking Sounds
  • – Produces a Rotten Smell After Some Use
  • – The Battery Loses Charge Quickly
  • The Mower Refuses To Cut Grass
  • – The Battery Appears to Bulge
  • – Poor Fluid Levels
  • 1. Assess the Condition of Your Battery
  • 2. Conduct a Voltage Test
  • 3. Prepare the Tools You Need
  • 4. Remove the Battery First
  • 5. Clean the Battery
  • 6. Fill the Battery With Fresh Electrolytes
  • 7. Recharge the Battery
  • 8. Check the Connections

What Are the Symptoms of Your Lawn Mower Battery Going Bad?

The symptoms of your lawn mower battery going bad include the engine not starting, the mower producing clicking noises and a rotten egg smell, the battery losing charge faster than normal, the mower refusing to cut grass, and poor fluid levels.

It is easy to tell if your lawn mower’s battery has gone bad. Some classic tell-tale signs of such a battery are that the engine won’t start, produce clicking noises and produce toxic fumes.

– The Engine Won’t Start

The first tangible sign of a bad battery is when the mower won’t start on the first pull. Even more, multiple ignition turns might be needed to get the engine fired as the situation worsens. This means the engine does not have adequate strength to fire the spark plug.

After multiple tries, it does so feebly when the engine fires up. It will crank much more slowly than normal, sometimes not at all. However, the engine not starting can also be due to a faulty spark plug, ignition button, or alternator. Make sure to check these out to see that they are working properly before moving on to the battery.

– Produces Clicking Sounds

A lawn mower is not supposed to make unnecessary sounds while working, so if it starts producing clicking sounds when you attempt to turn it on, the battery is running low on power. Recharging it properly might solve the problem.

Sometimes, the mower produces clicking noises and starts but does not turn over. This might mean that the battery is completely dead and in need of a replacement. When the lawnmower battery gets bad because of freezing and extreme weather conditions, this could cause problems with clicking and the engine starting without turning over.

– Produces a Rotten Smell After Some Use

A bad battery gets heated soon after use and produces toxic fumes. This is more pertinent for lead-acid batteries, where the sulfuric acid in the electrolyte gets turned into toxic fumes once the battery heats up.

In most of these cases, you will be able to smell hydrogen sulfide immediately because of its rotten egg smell. Be careful when touching the mower where the battery is located as it will be quite hot. Turn the engine off and let the mower cool down before doing anything else.

– The Battery Loses Charge Quickly

A lawn mower battery that either does not charge fully or stays charged afterward is going bad. Either the battery is too old or damaged, or there is something wrong with the charger.

With time, the battery’s capacity to hold charge does decrease naturally. After some years, you might notice having to charge it more often than before. However, if the battery is new or seems to be losing charge abnormally fast, then this is problematic.

If the battery refuses to charge altogether, in this case, your charger is faulty or the battery has gone bad.

– The Mower Refuses To Cut Grass

One uncommon and often ignored symptom of a gas-powered lawn mower’s battery going bad is that it will no longer be as efficient as before. It might work fine on thin, wispy grass, but as soon as you try to cut tall, thick grass, it will give up.

The battery is not strong enough to provide the engine with the power to cut through resistance. Check your blades to ensure there is nothing wrong with them, like a need for further sharpening. If they are okay, the battery is going bad and you need to fix it.

– The Battery Appears to Bulge

In riding mowers, the battery is usually located under the seating area and charged without taking it out of its box. That is why people often need to pay more attention to this vital symptom that the battery could be better.

When the engine stops turning off or producing clicking noises, take the mower’s seat off and take the battery out. It would help if you unscrewed some nuts and bolts here and there to loosen it. Notice the classic signs of battery wear down on all sides, including the bottom.

These signs include cracked edges, bulging sides, and blue-green corrosion on each battery terminal. Have a mechanic look carefully at this battery in case it becomes a health hazard.

– Poor Fluid Levels

Fluid levels within the battery are important indicators of a healthy vs. bad lawn mower battery. Check the fluid levels within each cell of the battery for this. In the case of lead-acid batteries, the electrolytes are a mixture of water and sulfuric acid.

Many things disturb the delicate balance of fluids within the electrolyte, such as overuse, overcharging, physical damage, or a battery that is too old. If the fluid levels within the battery are low, it is in an apt condition.

If the rest of the battery is in good condition, restoring the fluid levels will improve the battery. Buy a couple of bottles of distilled water and use them to get your battery working again.

How Do You Improve a Bad Lawn Mower Battery?

To improve a bad lawn mower battery, you should first assess the condition of the battery and conduct a voltage test. Prepare the tools that you will need and carefully remove the battery. Next, clean the battery and fill it with fresh electrolyte.

Unless the battery is completely dead, you can help improve its condition by cleaning it and changing its electrolyte fluid. Instead of buying expensive fluid from the market each time, make your electrolyte at home using Epsom salt and distilled water.

Assess the Condition of Your Battery

Before deciding whether to change or repair the battery, assess it thoroughly. First, ensure that each cell is filled with the electrolyte until the line.

Then give the battery a detailed examination to see if it is corroded, cracked, leaking, or bulging from anywhere. If any of these symptoms are present, then it is better to discard them for a new one.

Conduct a Voltage Test

A voltage test will determine whether or not the lawn mower’s battery is dead. Most lawn tractors and lawnmowers use a 12-Volt battery to run them. A fully-healthy 12-Volt battery, when fully charged, will display a voltage of around 12.6 to 12.8 Volts.

In case of an older mower with a six-volt or lower battery will also display a voltage of six volts when it is completely charged. You will need a multimeter to check this voltage. If there isn’t one present at home, borrow it from someone or order one online as they are pretty cheap.

Attach the multimeter to the battery and set it at DC at 13 volts. The meter’s red lead should be attached to the battery’s positive terminal, while the black lead goes to the negative terminal. The battery has gone bad if the meter reads less than 12.3 volts. If the voltage comes out fine, then proceed to the next step.

Prepare the Tools You Need

Use your safety goggles, full-sleeved clothing, and thick rubber gloves when dealing with the lawn mower engine and battery. Make sure your battery charger is functional, automatic, and has an in-built voltage regulator.

Find baking soda and distilled water at home or in your local supermarket. A plastic funnel is also a must-have item. Epsom salt (magnesium sulfate) is the last ingredient you will need.

Remove the Battery First

Turn the engine off, pull out the keys, and disconnect the spark plug. Around 90 percent of riding-style mowers have batteries under the driver’s seat. Pull up the seat, loosen the screws holding the battery in its chamber, and carefully pull it out.

For any other type of mower, consult the instructions manual to see where the battery is located. Disrupt the negative and positive terminals to remove the battery from its chamber first.

There will be caps on each battery cell which need to be removed. Usually, they will be located right on top of the battery and easily come off. Otherwise, a small flathead screwdriver will help you uncap the battery.

Clean the Battery

If the battery terminals have bluish-green corrosion, clean them first. A corrosion-cleaning solution with sandpaper will help clean the discoloration. The next step is to drain out all the existing fluid from the battery.

The insides of the battery need to be cleaned from sulfate buildup over the years. Measure 10 ounces of baking soda and dissolve it in one whole gallon of distilled water. Using the funnel, pour this solution into the empty cells of the battery and put their caps back on.

Now shake your battery thoroughly and leave it for a minute or two, then drain the solution out using the same funnel. Make sure you wear the thickest rubber gloves you have because these solutions can burn the skin.

Fill the Battery With Fresh Electrolytes

Now that it is clean, your battery needs fresh, new electrolytes added to it. You can buy electrolytes premade or make it yourself at home. It is simple, and you only need to add 15 ounces of Epsom salt to one gallon of distilled water.

Warm the water a little bit first, so the salt dissolves quickly. Again, the funnel will be helpful while pouring the electrolyte into each battery cell. There is a line on each cell until you fill it. Be mindful that you don’t overfill or underfill the battery. Screw the caps back on each cell, and your battery is ready.

Recharge the Battery

Next, it’s time to recharge your newly filled battery for the first time. Always use automatic chargers with adjustable settings options for charging.

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Set the charger to the slowest charging option, around two amperes per 24 hours. Yes, it would help if you gave the battery at least one whole day to become charged. During this time, keep the caps on individual cells slightly loose for any potential outflow of the charge.

Once the battery is charged to 100 percent, tighten the cell caps. Carefully place the battery back in its place within the mower. Attach the positive terminal and then the negative one when connecting the battery to the mower.

Check the Connections

Before restarting your newly charged battery again, check that all its connections with the engine are correct and secure. The negative and positive terminals should be attached properly to their required connections. If broken or damaged, the cables will not let the engine start, so it is better to replace them.


Before we conclude this article, here are the most pertinent points regarding a bad mower battery.

  • The first sign of a bad battery in the mower is that the engine will have a harder time starting and producing sounds while working.
  • Bad batteries lose charge rapidly and need frequent recharging. They also produce toxic gases and fumes, such as hydrogen sulfide, that smell like rotten eggs.
  • A bulging, cracked, or leaking battery is also symptomatic and needs to be replaced immediately.
  • If the battery is not dead, then take it out, clean it, and replace its electrolyte with a fresh one.

When the mower battery gets old, you must be careful about potential symptoms if it doesn’t work as well as before. This would ensure that you improve its condition or change it before it becomes a potential health hazard.

What Keeps Draining My Lawn Mower Battery? (CausesFixes)

Only a few days ago you charged your mower battery and took it for a spin. You hauled mulch around to the flower beds and zoomed around getting your landscaping done. All was right with your mower. Fast forward a few days, the grass needs cutting but the battery needs to charge again? What’s going on? The same thing happened the last time you used it, and you get a repeat this week. You ask yourself “why is my mower battery draining?”

We will be going over possible issues that could be draining your lawn mower battery, how to fix them, and if a bad solenoid will drain a lawn mower battery. Get comfortable, crack open a cold one, and let’s start solving the problem.

What Keeps Draining My Lawn Mower Battery? (The Short Answer)

Your lawn mower battery could be draining from a number of causes such as loose, dirty, or corroded battery cables, electronic drain, or a bad battery. There could also be a faulty charging system, a failing voltage regulator, or other issues that are draining your lawn mower battery.

Possible Reasons for a Lawn Mower Battery Not Holding a Charge

Dirty or Corroded Battery Cables

It happens to your automobiles, and it can certainly happen to your lawn mower battery. You open up the hood, there on the battery cables is a whitish, powdery crust building up around the terminals.

Hydrogen gas escapes from your battery and it reacts with the metal on the battery posts and cables causing corrosion. If it gets too bad, your lawn mower battery will not charge or send power to the mower at all. It’s annoying, but a simple fix.

How to Fix: Put on your safety gear, chemical-resistant gloves, eye protection, all that stuff. There could be some battery acid, or the corrosion could be irritating to skin and mess up clothing.

Disconnect the battery terminals, pour baking soda (you can also use battery cleaner from your local auto parts store) around the corroded areas, and then pour a little bit of water on the baking soda to neutralize the corrosion and battery acid.

If the corrosion is stuck on, you can use a small wire brush to scrape it off, then use more baking soda and water to dissolve the residual corrosion. Use paper towels next to clean and dry the areas then reattach the cables, charge your battery again, and you’re good to ‘mow’.

Loose Battery Cables

If you have a loose connection, then of course the battery is going to struggle to keep everything running correctly. The constant vibrations of the motor over time can cause the bolts to loosen slightly causing your battery to work overtime to power your lawn mower.

How to Fix: Simply wiggle all the cable connections to see if they are loose. If any need tightening, clamp them down properly then get back to tending your yard.

Leaving the Key on in the Ignition, or Leaving Accessories on

This could happen. I’m forgetful at the best of times, and even more so when I’m in a hurry. I get it, things happen, maybe the key wasn’t turned completely off, or the lights were on in the daytime, and you just didn’t see that they’d been left on. We’re all very busy people and simple mistakes like this do happen.

How to Fix: To fix this problem simply double-check yourself. Take the keys out and hang them somewhere nearby or put them in the cupholder of your mower. After you park it, take a quick look to make sure all the lights and fancy gadgets are turned off.

A Bad Alternator

The alternator helps to keep the electrical system running and recharges the battery while the engine is running. If the alternator is failing, then it means the battery has to take up the slack and it’s not getting enough charge to keep it in tip-top shape.

How to Check: To check the alternator, turn the mower’s lights on, leave them on then turn off the mower. If the alternator is good, then the lights will dim when the motor stops. If the lights remain the same intensity, then it means the battery is carrying the load and the alternator needs to be replaced. Once that is fixed, the battery will be recharged every time you run your mower.

The Voltage Regulator is Going Bad

If the voltage regulator is going bad you’ll notice some obvious symptoms, namely that it will cause the battery to drain pretty quickly.

How to Check: You will need your trusty multimeter to check for this problem. Set it to check the voltage, turn on the mower just enough to get a load running through the electrical system. Check the battery terminals with the multimeter.

You are looking for voltage between 13.8 and 14.5 volts. Below 13.8 means your battery is failing or is not sufficiently charged, and above 14.5 means you have a fault in the voltage regulator, and it needs to be replaced.

The Battery Needs Maintenance

Another reason your battery is not able to keep a charge is that your battery needs some maintenance. Lawn mower and car batteries are known as wet cell batteries. There is sulfuric acid inside the battery cells and over time gasses escape, the liquid is reduced, resulting in a poor performing battery. Learning how to restore a lawn mower battery can save you a few bucks when this happens.

How to Fix: You can check this by first donning your protective gear. Gloves, safety glasses, you know the drill.

Next, carefully pop off the plastic covers to the battery and peer inside. If the liquid is lower than the round ports, it needs water. Use a small funnel and pour distilled water into the ports to raise the liquid level only to the bottom of the ports. You don’t want to overfill these holes. Put the covers back when you’re done, give the battery a good charge and you should be set.

Now is also a good time to check for dirt and corrosion at the battery terminals.

Not Running Your Mower at Full Throttle

Now I’ve been guilty of this in the past. I was young, just bought my first John Deere riding mower and I wanted to eventually pass it on to my grandchildren. In an effort to reduce the strain on the mower, I didn’t run it at full throttle. Little did I know, mowers are designed to run with the “pedal to the metal.”

Along with other issues that can occur from not pushing the throttle to the top, it can drain your battery. If the motor is not running at full RPMs, the battery may not be getting a full charge. So go ahead, crank that throttle up and run your mower full blast. It was built to run full throttle.

Your Battery is Failing

Another reason your lawn mower battery keeps draining could be because it is heading toward the end of its life cycle. Mower batteries typically have a lifespan between 3 to 5 years with proper care.

Of course, you can get the occasional lemon that doesn’t even tick on that long, but if you can’t find anything else that keeps draining your battery, you might have to think about replacing your old one. When you’ve got a battery that’s soon to be a dead lawn mower battery, the simple fix is to buy another one. I know your wallet isn’t going to be excited about that, but once the battery starts failing, there’s nothing else that can be done about it.

Electronic Drain

With all the new advances related to everything electronic, your battery could be experiencing a parasitic electronic drain. This happens when the lawn mower is turned off, but a tiny electrical charge is still sucking minute doses of power.

Given time, this could weaken or completely drain the battery. This can be difficult to check for and to fix, but if all other avenues have been exhausted, you may have to check for this. You will need a multimeter for this particular diagnosis.

How to Check: Set your multimeter to ammeter mode then set the probes on the battery posts when the mower is turned completely off. If you get a reading of more than 1mA, then your electrical system is still drawing current off the battery via a relay system, or a component in the mower that has a standby mode.

To remedy the parasitic drain, you may have to take it in to get your mower serviced. You could also disconnect the battery each time to save it from the power-sucking culprit or keep a maintenance charger on the battery when not in use.

Will a Bad Solenoid Drain the Battery on a Lawn Mower?

The solenoid is the part connected between the battery cable and the starter. A bad solenoid will not drain the battery on a lawn mower – its main purpose is to send a larger charge to the starter to get the mower running. If the solenoid has gone bad, assuming the battery is still good, you will probably only hear a small click when you attempt to start your mower.

Class Dismissed

I hope this has answered all your questions as to what keeps draining your lawn mower battery. Now you don’t have to continue asking yourself or your neighbors why your John Deere tractor or your Kohler engine keeps draining the battery. You have the knowledge to diagnose and fix the draining battery yourself.

By checking the battery cables for corrosion or a loose fit, keeping up with battery maintenance, and making sure everything is turned off (yes, I’m speaking to myself here) as well as checking for alternator, voltage regulator problems, or electrical parasites you can find out what keeps draining your mower battery. Also, replace the battery if it has reached the end of its life cycle, and keep that throttle running high, so you can keep that battery charged, and your lawn neat and tidy.

About Tom Greene

I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the lawn mower guru (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!

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