Battery For John Deere La135 – Finding The Right Power For Your Mower
The John Deere LA135 requires a 12-volt Group U1 battery with a minimum of 300 Cold Cranking Amps (CCA). For optimal performance and easier starts in cold weather, many experts recommend a battery with 340 CCA or higher.
Ensure the terminal orientation matches the original factory setup, typically with the positive terminal on the left side when the terminals are facing you. High-quality lead-acid or AGM options from brands like Interstate, DieHard, or John Deere StrongBox are top choices.
You rely on your John Deere LA135 to keep your lawn looking pristine throughout the growing season. There is nothing more frustrating than heading out for a Saturday morning mow only to hear a faint clicking sound instead of a roaring engine.
Finding the correct battery for john deere la135 mowers is the first step toward ensuring your machine starts reliably every time. Selecting the right specs will not only save you time at the store but also protect your mower’s electrical system from unnecessary strain.
In this guide, I will walk you through the exact specifications, installation steps, and maintenance secrets I’ve learned from years of servicing lawn equipment. You will learn how to maximize your battery life and avoid the common pitfalls that leave many DIYers stranded in the shed.
Understanding the Specs for a Battery for John Deere La135
When you walk into a parts store, the sheer number of black plastic boxes can be overwhelming. For the John Deere LA135, you specifically need a Group U1 battery. This refers to the physical dimensions of the casing, ensuring it fits snugly in the battery tray under the seat.
Voltage is non-negotiable for this model, as the LA135 runs on a 12-volt system. Using anything else could fry your wiring harness or fail to engage the starter motor entirely. Most standard lawn and garden batteries meet this requirement, but quality varies significantly between brands.
The most critical performance metric is the Cold Cranking Amps (CCA). This number represents the battery’s ability to start the engine in cold temperatures. While the factory minimum is 300 CCA, I always suggest stepping up to 340 or even 350 CCA if you live in a region with chilly spring mornings.
The Importance of Terminal Orientation
One mistake I see homeowners make often is buying a battery with the terminals reversed. On the LA135, the positive terminal should be on the left side when the terminals are positioned closest to you. If you buy a “U1R” (the R stands for reversed), your cables may not reach.
Stretching cables to fit a reversed battery puts mechanical stress on the terminal posts. This can lead to internal cracks in the battery or even a short circuit if the positive cable touches the metal frame of the mower. Always double-check the “+” and “-” markings before leaving the store.
Standard lead-acid batteries are the most common choice, but Absorbent Glass Mat (AGM) batteries are gaining popularity. AGM batteries are spill-proof and tend to handle the vibrations of a bumpy lawn better than traditional flooded batteries, though they come at a higher price point.
Selecting the Best Battery for John Deere La135
When choosing a battery for john deere la135, you have several reputable paths to take. Many owners prefer the John Deere StrongBox line, which is engineered specifically for the vibration and heat cycles of lawn tractors. These are available at local dealerships and offer a perfect fit every time.
If you prefer shopping at big-box retailers or auto parts stores, the Interstate Batteries or DieHard Gold series are excellent alternatives. Look for a “Lawn and Garden” specific model that lists 340 CCA on the label. These brands often provide better warranties than generic “value” brands.
Keep in mind that the LA135 uses an electric PTO (Power Take-Off) to engage the mower blades. This system puts a constant draw on the charging system while you are mowing. A high-quality battery acts as a buffer, ensuring the electric clutch receives steady voltage without overheating.
Lead-Acid vs. AGM Technology
Traditional flooded lead-acid batteries are affordable and reliable if maintained. However, they require you to check fluid levels occasionally and can leak acid if the mower is tilted during cleaning or blade sharpening. For most casual gardeners, these are perfectly adequate for seasonal use.
AGM batteries, on the other hand, are completely sealed. They are highly resistant to the vibration caused by the 20-horsepower engine and uneven terrain. If you have a particularly hilly yard or if you tend to forget about battery maintenance during the winter, the extra investment in AGM is often worth it.
Regardless of the brand, always check the date code on the battery before purchasing. You want a unit that was manufactured within the last three to six months. Batteries that sit on a shelf for a year without a charge can develop sulfation, which permanently reduces their capacity.
Step-by-Step Installation for Your New Mower Battery
Safety should always be your primary concern when working with lead-acid batteries. Before starting, put on safety glasses and heavy-duty work gloves. Battery acid is highly corrosive, and a small spark near the terminals can lead to an accidental discharge or injury.
Park your John Deere LA135 on a flat, level surface and engage the parking brake. Turn off the ignition and remove the key to ensure no power is flowing through the system. Lift the seat to access the battery compartment, which is located directly beneath the driver’s position.
Start by disconnecting the negative (black) cable first. This is a crucial safety step; if your wrench touches the metal frame while loosening the negative terminal, nothing happens. However, if you start with the positive terminal and touch the frame, you will create a dangerous short circuit.
Cleaning and Prepping the Terminals
Once both cables are removed, take a moment to inspect the cable connectors. If you see white or green powdery growth, that is corrosion. Mix a small amount of baking soda with water and use an old toothbrush to scrub the connectors until they are shiny and clean.
Remove the old battery and check the battery tray for debris or dried grass. A clean tray prevents the battery from bouncing around, which can damage the internal plates. Place the new battery for john deere la135 into the tray, ensuring it sits level and secure.
When reconnecting, reverse the order: connect the positive (red) cable first, then the negative (black) cable. Tighten the bolts firmly but do not over-torque them, as the lead terminals are soft and can strip easily. Apply a thin layer of dielectric grease to the terminals to prevent future corrosion.
Maintenance Tips to Triple Your Battery Life
A typical lawn mower battery lasts three to five years, but poor maintenance can kill it in a single season. The most common killer of the battery for john deere la135 is “parasitic drain” or long periods of inactivity. During the off-season, your battery naturally loses its charge.
I highly recommend using a smart trickle charger (also known as a battery maintainer) during the winter months. Unlike a standard charger, a smart maintainer monitors the voltage and only provides power when needed. This prevents overcharging, which can boil the electrolyte out of the battery.
If you don’t have a charger, remove the battery from the mower and store it in a cool, dry place like a basement or insulated garage. Do not leave it on a concrete floor for months, as the temperature fluctuations can accelerate self-discharge. Placing it on a wooden shelf or a piece of cardboard is a simple pro trick.
The Role of the Charging System
Your John Deere LA135 has a built-in alternator that charges the battery while the engine runs. However, this system is designed to maintain a charge, not to recharge a completely dead battery. If you jump-start your mower and only run it for ten minutes, the battery will likely be dead again the next time you try to start it.
To keep the system healthy, ensure you are running the engine at full throttle while mowing. This maximizes the output of the charging system and provides enough power to run the electric PTO. If you notice your headlights flickering or the mower blades slowing down, your battery or alternator may be failing.
Periodically check the air intake screens on your engine. If the engine runs too hot because of grass buildup, the heat can transfer to the battery compartment. Excessive heat is just as damaging to lead-acid batteries as extreme cold, as it causes the internal chemical reactions to break down faster.
Troubleshooting Common Starting Problems
If you have installed a new battery for john deere la135 and the mower still won’t start, the problem might lie elsewhere in the electrical loop. A common culprit is a blown fuse. Check the 20-amp fuse located near the starter solenoid; if the wire inside is broken, the mower will appear completely dead.
Another frequent issue is a faulty safety interlock switch. The LA135 has switches under the seat, on the brake pedal, and on the PTO lever. If the mower doesn’t “think” the brake is depressed or the blades are disengaged, it will prevent the starter from turning over to protect the operator.
If you hear a rapid clicking sound when turning the key, it usually indicates that the battery has enough voltage to engage the solenoid but not enough amperage to turn the heavy engine. Double-check your terminal connections for tightness. Even a slightly loose cable can prevent the high current needed for starting from reaching the motor.
Testing With a Multimeter
For those who want to be precise, a digital multimeter is an invaluable tool. A fully charged 12-volt battery should read approximately 12.6 to 12.8 volts when the engine is off. If it reads below 12.2 volts, it is significantly discharged and needs to be placed on a charger.
While the engine is running at full throttle, the reading should jump to between 13.5 and 14.5 volts. If the voltage stays at 12.6 or drops while the engine is running, your voltage regulator or stator may be faulty. This means the mower is running off the battery’s stored energy rather than the engine’s power.
Finally, inspect the spark plug and fuel filter. Sometimes a “no-start” condition is mistaken for a battery issue when it is actually a fuel delivery problem. If the engine cranks vigorously but won’t catch, the battery is doing its job, and you should look toward the carburetor or ignition system instead.
Safety and Environmental Responsibility
When you replace the battery for john deere la135, you are left with a heavy block of lead and sulfuric acid. It is illegal and environmentally damaging to throw these in the regular trash. Lead-acid batteries are one of the most successfully recycled products in the world.
Most retailers that sell batteries are required by law to accept your old one for recycling. In many states, you will pay a “core charge” when you buy a new battery. This fee is refunded to you when you bring back the old unit. This incentive keeps millions of pounds of lead out of landfills every year.
When transporting the old battery, place it in a plastic bin or a sturdy cardboard box. This prevents any residual acid from leaking onto your vehicle’s carpet or upholstery. If a leak does occur, neutralize the acid immediately with a mixture of baking soda and water to prevent permanent damage to your car.
Frequently Asked Questions
What Is the Exact Battery Size for a John Deere LA135?
The LA135 uses a Group U1 battery. The physical dimensions are approximately 7.75 inches long, 5.125 inches wide, and 7.31 inches high. Ensure the positive terminal is on the left side.
Can I Use a Car Battery for My John Deere Mower?
No, you should not use a standard car battery. Car batteries are much larger and will not fit in the designated tray. Furthermore, the charging system of a lawn tractor is not designed to handle the high-capacity recharge requirements of an automotive battery.
How Long Should a John Deere LA135 Battery Last?
With proper care and winter storage, you can expect 3 to 5 years of service. If left in the mower during freezing temperatures without a maintainer, a battery may fail in as little as one or two seasons.
Why Does My Battery Keep Dying Every Week?
This is often caused by a faulty voltage regulator or a parasitic draw. Check to see if you left the headlights on or if a safety switch is grounded. Also, ensure you are mowing at full throttle so the alternator can keep up with the PTO demand.
What Does CCA Mean for My Mower?
CCA stands for Cold Cranking Amps. It measures how much power the battery can deliver for 30 seconds at 0 degrees Fahrenheit. For the LA135, a higher CCA (340+) helps overcome the resistance of thick oil and cold engine parts during early spring starts.
Conclusion
Maintaining the right battery for john deere la135 is the backbone of a reliable lawn care routine. By choosing a Group U1 battery with at least 340 CCA and ensuring the terminal orientation is correct, you set yourself up for a stress-free mowing season. Remember to prioritize safety during installation and never skip the winter maintenance steps.
A healthy battery doesn’t just start the engine; it supports the entire electrical system, from the headlights to the electric PTO clutch. Take the time to clean your terminals and use a smart maintainer during the off-season. Your John Deere is a precision machine, and with the right power source, it will continue to deliver that signature “green and yellow” performance for years to come.
Taylor pairs an engineer's eye with years of hands-on work in soil, lawns and outdoor machinery. He tests ideas in his own garden, keeps tractors and mowers running himself, and speaks to local horticulture groups. Every Garden Aider guide is written to be practical, accurate and safe to follow.
“To bring life alive, you just need to mix some love with the compost, bedding, and gardening machines.”