Why is my lawn mower battery losing charge?

Author: Karolann King  |  Last update: Friday, April 4, 2025

If your battery is used on a walk-behind mower, you should try charging the battery using a dedicated battery charger. If the battery still won't hold a charge, the battery is likely faulty and should be replaced with a new one.

Why does my lawn mower keep draining my battery?

Even if the top of the battery is very dirty, this can drain a battery as well, so make sure the battery is clean and the connections are clean, tight, and corrosion free. Next is to check if any of the relays are staying activated after the key is off... if a relay is stuck 'on' it can drain the battery.

Why won't my lawn mower battery hold a charge?

If your lawn mower battery won't hold a charge, verify connections are clean and tight first, then connect it to the charger. If it isn't fully charged within 8 hours, your battery is dead and you'll need to replace it. If your lawn mower battery does charge fully, the charge should not drain if it is not in use.

What could be draining my battery while it's off?

Things that can drain your battery with the car turned off include: all sorts of things, unfortunately. Accidentally leaving the headlights on, or leaving the dome light on, or leaving the door ajar enough to leave the dome light on, are probably the most frequent causes. The battery cables can be bad and have a short.

How do I know if my alternator is bad on my riding mower?

Alternators power the small engine while it is running, keeping the battery charged by circulating power back back through the system. For the easiest alternator test, simply turn on the headlights to your lawn mower or outdoor power equipment. Then, turn off the engine. If the lights dim, the alternator works.

Why Does My Riding Lawn Mower Battery Keep Dying? Small Engine Repair

How to tell the difference between alternator and battery problems?

One of the most obvious signs is if the car dies after a jump start. The alternator should provide enough current to keep the vehicle running even with a bad battery. If it doesn't, then your alternator needs to be examined.

Does a riding lawn mower charge the battery while it's running?

A riding lawn mower with an especially small engine may have a 6-volt battery. The lawn mower's alternator keeps its battery charged. A few hours of mowing recharges it the same way hours of highway driving can keep your car battery mostly charged.

How do you diagnose what is draining my battery?

To find the source of the drain, start by removing each fuse one at a time and checking the multimeter for any changes in the reading. When you see a significant change in the reading, you've found the circuit causing the parasitic drain. This will help you identify which component or system is responsible.

Why is my battery losing charge overnight?

Some of the possible reasons why your car battery can be drained overnight include accidentally leaving the lights on, having a faulty relay causing parasitic draw from accessories, and failing to replace an underperforming alternator among others. Experts recommend replacing your car battery every four or five years.

Can a bad ground cause battery drain?

Common causes of high parasitic drain include a circuit that's shorted to ground or a computer module that isn't going to sleep.

What kills the battery on a lawn mower?

Defective voltage regulator – The voltage regulator allows the proper amount of voltage to be sent from the alternator to the riding mower's battery. A defective regulator can prevent the battery from receiving enough voltage, causing the battery to drain quickly.

Why do I have to keep charging my lawn mower battery?

Much like with cars, a riding lawn mower has an alternator that recharges the battery while you run it. As long as you use your lawn mower or tractor regularly, your battery will stay charged up. Lawn mower batteries begin to discharge when they aren't used.

How do you fix a battery that doesn't hold a charge?

Using Epsom salt is another way to recondition a battery that won't hold charge. Epsom salt or magnesium sulfate can help dissolve solid salts that have formed around the battery plates over time. Simply mix one part Epsom salt with three parts distilled water, and pour the solution over the battery cells.

What is the life expectancy of a lawn mower battery?

The average lifespan of a lawn mower battery is approximately three years. The typical estimated life of a Lithium-Ion battery is about two to three years or 300 to 500 charge cycles, whichever occurs first. Some high-quality lithium-ion batteries can last up to five years with proper care and maintenance.

What is running that is draining my battery?

Running several apps at once or having lots of apps running in the background can increase battery drain. Screen brightness set to max- Screen brightness impacts power consumption, so keeping it maxed out all the time could make your battery drain faster.

Can you bring a lawn mower battery back to life?

Try a Charging Session

Connect your questionable battery to a lawn mower battery charger. Set it for 12 volts, which is the standard in the industry. Most lawn and garden devices have this voltage rating as a way to keep consumers safe from any shock. Allow the charger to power up the battery for up to eight hours.

How do I stop my battery from draining while charging?

Overheating can contribute to battery drain while charging. To address overheating issues, ensure that your phone is not exposed to direct sunlight or placed on surfaces that retain heat, such as blankets or pillows. You can also close unnecessary apps running in the background, as they can cause your phone to heat up.

What is the most common cause of parasitic battery drain?

Common causes of parasitic battery drain include short circuits, electrical devices that remain energized and a faulty battery or alternator diode. Signs of a worn battery include difficulty starting the car, dim headlights, backfiring, dashboard lights but no starting and the need for frequent jump starts.

Why is my battery draining so fast and taking so long to charge?

The sudden drain in your phone's battery can be due to several reasons. It could be because of a recent software update that is consuming more power, or applications running in the background, high screen brightness, enabled push email settings, or possibly a faulty battery.

What could be draining my battery while its off?

Parasitic draws, such as interior lights, door lights, or faulty relays, can drain the battery even when the car is off.

How do you work out what is draining my battery?

How to find out what apps are draining your Android phone's...
  1. Open Settings. Log in to your Android device and pull down the Notification Shade twice. ...
  2. Access the Battery details. Once in Settings, tap Battery. ...
  3. Open Battery Usage. In the resulting screen, tap Battery Usage. ...
  4. Take action.

How to check if alternator is draining battery?

To confirm your suspicion, set your multimeter to AC Volts (ACV) and reconnect the battery cable. With the engine running, touch the red lead to the positive battery post and the black lead to the negative post. If there's more than 0.5 ACV, the alternator likely has one or more bad diodes.

How do I know if my lawn mower battery is bad?

Here are helpful tips for identifying if you need a new lawnmower battery:
  1. Check the connections of your lawnmower. Notice that your lawnmower isn't cutting as smoothly or holding its charge for long periods. ...
  2. Try Charging the lawnmower. ...
  3. Listen for a Clicking Sound coming from your lawnmower.

Is it OK to leave a lawn mower battery on the charger?

Key Takeaways. Leaving a battery on the charger can cause overcharging, heat buildup, and potential fire hazards. Always remove it once fully charged.

How do I keep my riding lawn mower battery charged?

Hooking up the battery tender intermittently will keep the lawnmower battery and all others charged and ready to go. Every time you hook up the tender, allow enough time for a full charge to be achieved before unhooking.

Previous article
Can vacuuming improve air quality?
Next article
What is the alternative to hand wash only?