How to Charge, Maintain Lawn Mower Batteries

lawn mower battery

Environmental consciousness and advances in electric mower performance are convincing more Americans to buy electric lawn mowers to replace their gas ones. But with that choice comes the responsibility of learning how to charge and maintain lawn mower batteries.

From the newest $100,000 Tesla to the humble golf cart at your local course, the batteries that power them have come a long way, both in power and in the amount of care required.

Types of Electric Lawn Mower Batteries

Note: In this article, we will be talking exclusively about electric lawn mowers.

Electric push mowers, which comprise about 80% of the electric mower market, use a rechargeable battery pack as a power source. To recharge the battery pack, remove it from the mower and use an appropriate battery charger.

Electric riding mowers use larger batteries (like car batteries). For example, the Ryobi RY48110 uses four 12-volt, lead acid batteries connected in a series. To charge them, you need specific charger cables or chargers that plug into the wall on one side and into the mower on the other through a built-in charging port in the mower itself.

How Will I Know When My Battery Starts to Wear Out?

Gary Koenig
Associate professor Gary Koenig, University of Virginia

“When it starts to wear out, the biggest thing you’ll see is it won’t last as long”, says Gary Koenig, associate professor in chemical engineering at the University of Virginia. 

Older batteries become more resistive internally, and have to work harder to complete the same amount of output, he says. Batteries also have some amount of self-discharge, sometimes called “leakage current” or “parasitic current,” Koenig says.

This means a fully charged battery will slowly drain while off the charger. However, the discharge takes place slowly. It may leak out only a few percentage points per month. So if you’ve left a fully charged battery in the garage over winter, it’s not going dead if it only lasts 50 minutes on that first cut come spring. No trickle charger needed. Just pop the battery back on the charger until it’s fully charged for that first cut of the season.

Charge an Electric Riding Lawn Mower Battery

Here is a step-by-step guide to charging an electric riding lawn mower battery

  1. Stay safe. Put on protective clothing, including gloves and safety glasses.
  1. Unplug the charger. Unplug the charger from the electrical outlet.
  1. Locate the battery. If you’re using a riding lawn mower, the battery is found underneath the seat. The best way to find the battery is to consult the owner’s manual.
  1. Connect the charging cables. A lawn mower has two charging cables: a red positive cable, and a black negative cable. Each connects with the battery terminal’s respective side. Connect the red cable before the black cable.

    Note: Some lawn mowers have tabletop charging stations, so homeowners with smaller lawns might benefit from a small mower with a tabletop charger.
  1. Match voltage between the mower and the charger. Your battery’s voltage is indicated by an amp (ampere) rating. The higher the amp rating, the greater its amperage, meaning a stronger electric current can flow through it. Toggle the charger’s voltage to match your mower’s battery voltage.
  1. Plug the charger in. Make sure the cable is securely connected to your battery, and not touching any metal parts inside or outside the lawn mower. If you connect the cable incorrectly, it could damage your battery and/or charger.
  1. Start charging. The charger will indicate if the battery is charging or discharging. A lawn mower battery typically charges at a rate of 10 amps per hour. Wait until the battery is fully charged before disconnecting the charger.

    Disclaimer: This information is for educational purposes only. Always follow the manufacturer’s instructions.
Photo Credit: Lindalen / Wikimedia Commons / CC0 1.0

When to Charge a Lawn Mower Battery

Most manufacturers recommend charging your lawn mower battery at least once a month during the summer months and at least once a week during the winter months.

Below are some of the most common times you should hook your battery up to a charger.

  1. After buying a new lawn mower. Charge the lawn mower’s battery before using it. This will give your machine a good initial start.
  1. If your lawn mower seems to be failing. If it seems like your lawnmower isn’t working, check its battery. Usually, all you need to do is charge the battery to get your lawnmower back in shape.
  1. After you’re finished mowing the lawn. After cutting the grass, leave the lawnmower unplugged so the battery can rest and re-energize. If your lawn mower has a built-in alternator, your battery will remain charged due to power being circulated through the lawn mower.
lawn mower battery
Photo Credit: Tony Buser / Flickr / CC BY-SA 2.0

Dos and Don’ts of Charging a Lawn Mower Battery


✓ Choose batteries and chargers from the original manufacturer, engineered to work the best with the corresponding tool.

✓ Transport and store batteries away from metal objects like keys, coins, screws and nails. The same goes for liquids. These can connect the positive terminal and negative terminal and short the battery out. 

✓ Remove the battery when storing the tool.

✓ Keep the battery dry, clean and free from oil and grease.

✓ Monitor the battery’s performance. Stop use if the battery is overheated, damaged or modified.

✓ Protect the battery terminals. Barry says terminals are the battery’s weak spot, where water, dust and dirt get in. Store batteries where terminals can be protected.


✗ Throw the battery in the trash. Always follow local regulations and recycle the battery at a local recycling center. 

✗ Charge the battery in excessively hot or cold temperatures, which Koenig says can also cut into the battery’s useful life. Different manufacturers and products set different temperature limits, found in their owner’s manuals.

✗ Place batteries near fire or heat, including a pilot light, which increases the chance of explosion. 

✗ Charge the battery in a damp or wet location.

✗ Try to bypass any safety or control devices to change the voltage rate at which a battery charges, Koenig says. 

Sources: Barry, Koenig, the Power Tool Institute, Inc., Ryobi and Ego.

Useful Advice for Recharging Batteries

Lots of advice — some of it conflicting — circulates about whether to leave the battery on the charger all the time, and whether to let the batteries drain completely before recharging.

For lithium-ion batteries, overcharging and completely discharging them can cut down on the overall life of the battery, Koenig says.

It’s “generally better not to discharge it all the way,” he says. “Don’t run it very low.”

That means keeping the battery’s charge level at 20-percent or better. Discharging it below that will accelerate fade, or the battery’s slow degradation. 

And when recharging, disconnect when it reaches 100-percent. 

If you’re curious about which type of electric lawn mower is best for you, check out our guide on the best electric lawn mowers for homeowners.

Tips for Maintaining Your Lawn Mower Battery

Proper battery maintenance will help your lawn mower perform at its best and live longer. Here are a few tips to help extend your lawn mower’s battery life.

  1. In the winter, your battery will lose life due to a lack of use. To keep it charged during the off-season, disconnect it from your lawn mower and store it in a cool, dry place. Use a trickle charger to keep it charged during those cold winter months.
  1. Don’t operate the lawn mower with a dead battery.
  1. When taking your lawn mower indoors, turn it off to avoid damaging the battery.
  1. Don’t leave the battery on the lawn mower all day long. This will cause your lawn mower to overheat, shorten its battery life, and damage the lawn mower.
  1. Always charge the battery at least once a month.
  1. Never use the lawn mower battery to jump start a car. Doing so will damage your lawn mower, and unlike car batteries, lawn mower warranty doesn’t cover your batteries.
  1. Always remove the lawn mower battery from the charger when it reaches a full charge.

At the end of the day, it’s recommended to let the owner’s manual have the final say.


How Long Does it Take for my Lawn Mower to Fully Charge?

Charging types for electric lawn mowers depend upon both battery and charger type. Some electric lawn mowers charge within 100 minutes and run for 1 to 2 hours. Larger lawn mowers can charge for 3 to 4 hours and run for 1.5 hours.

The type of lawn mower also plays a part in charging time. For example, Black+Decker’s cordless lawn mowers use a two-stage charging system where the first stage charges to 75%, while the second stage adds the remaining 25%.

Small Lawn Mowers

MowerBattery TypeCharging Time/Cutting Time
Snapper push mowerLithium-Ion30 minutes/25-30 minutes
Sun Joe light mowerLithium-Ion1.5 – 2 hours/45 minutes
Cub Cadet smaller sit on mowerLithium-Ion4 hours/1 hour

Large Lawn Mowers

MowerBattery TypeCharging Time/Cutting Time
LEO self-propelled commercial mowerLithium-Ion2 hours/50 minutes
Cub Cadet big sit on mowerLithium-Ion4 hours/1.5 hours
Weibang big sit on mowerLithium-Ion12 hours/2.5 hours

Source: The Garden Gadgets

How Much Does it Cost to Replace a Dead Mower Battery?

Unfortunately, batteries are the most expensive part of cordless push mowers. For example, a Ryobi 20-inch 40-volt mower costs about $400 at Home Depot. A replacement battery for the same model is about $200 at Home Depot. The $465 Ego 21-inch 56-volt mower Amazon offers runs on a $260 battery

Replacing riding lawn mower batteries or lawn tractor batteries is cheaper, but you may need to buy more of them. For the Ryobi RY48110, which costs around $2,500 new, replacing a dead battery will cost you about $66. That means buying four on Amazon would cost $264.  

What is the Lifespan of a Lawn Mower Battery?

With proper care, a lead acid lawn mower battery should last about 3 to 4 years. Most battery-powered motors have lithium-ion batteries that can last for up to 5 years.

Several factors that affect a battery’s life span are overcharging batteries, extreme temperatures (hot or cold), and making sure your battery is clean and dry. Keeping mowing decks clean can help the motor run more efficiently and the battery last longer.

Call in a Professional

If you have enough trouble keeping your cell phone battery charged, let a local LawnStarter pro take care of the mowing and maintenance in your lawn.

Main Image Credit: Drake McLemore / iStockPhoto

Derek Lacey

Derek Lacey

Formerly the agriculture writer for the Hendersonville Times-News, Derek Lacey’s articles have appeared in U.S. News & World Report, The Charlotte Observer, News & Observer, and The State. He has won 15 awards from the North Carolina Press Association and GateHouse Media, for pieces ranging from news features and investigative reporting to photography and multimedia projects.