The most common cause of battery failure is sulfation, a buildup of lead sulfate crystals.
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.
This is because there is a constant chemical reaction happening between the acid and the lead, as well as repeated vibrations from the lawn mower engine and the bumps and jostles of the mowing process.
The reason your battery will not hold a charge is because there is a problem with your charging system. The most likely cause is a failed voltage regulator, which is attached to the outside of the blower housing.
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.
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.
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.
Key Takeaways. Leaving a battery on the charger can cause overcharging, heat buildup, and potential fire hazards. Always remove it once fully charged.
Alternator Test on Your Small Engine
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. If not, it doesn't.
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.
Signs Your Lawn Mower Battery Needs Replacing
The engine turns over slowly. The battery can't store or deliver the required energy to spin the engine over as quickly. It frequently needs to be charged. Needing to recharge the battery often is a sign that there's an internal issue like shedding lead material.
Its internal electronics will discharge it partially if not used over a period of 30 days or so. Storing the battery in the mower or other device with the device turned off and key removed is OK, but safest practice is to remove the battery and place it where young inquisitive idle hands can not reach.
Can you overcharge a lawn mower battery? There is no risk of overcharging a lawn mower battery.
If the engine will not crank, you likely have a problem with... Discharged / defective battery or faulty electrical connections. To address these issues, check the battery and charging system for problems. Faulty parts: potentially the safety interlocks, starter motor switch (open circuit) or solenoid.
Why do Lawnmower and Lawn Tractor batteries fail? There can be a few reasons why your battery may fail, but one of the most common is due to a lack of use. If you're not using your lawnmower or lawn tractor enough and it sits, perhaps in your garage for a period of time, the battery needs to be charged.
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.
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.
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.
If regular charging doesn't work, you can attempt to jump start the battery. While it's technically possible to jump start a riding mower using a car, it's not the best choice. Lawn mower batteries are typically more difficult to access than car batteries.
2. How long does a 12 volt lawn mower battery last. The lawn mower battery can last for years, usually 3-5 years if it is properly maintained during the off-season or daily. If you want your mower battery to last long, take care of the charge methods and store it carefully.
Charge your batteries regularly and never let them discharge completely. Use the charger that was designed for your battery. If the charger doesn't shut off automatically, be sure to remove the power source as soon as a full charge is reached. Keep the battery terminals clean.
You can expect to get anywhere from six to ten years out of your riding mower, or longer with proper care and maintenance. Like most machines, riding lawn mower life varies depending on a number of factors including terrain, maintenance and upkeep, number of hours used, and more.