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How to Get the Most Out of Your Lawn Mower Battery

Power - by Bryan Veldboom - updated on 5/23/2023

Angled side view of an orange and black riding lawn mower

Where should you go to replace the battery for your lawn mower or lawn tractor? Batteries Plus, of course. We feature top-quality lawn tractor and mower batteries from trusted brands like Duracell, each with their own limited 6-month warranty. A new lawn battery should last between three and five years. In order to achieve that, however, it's important to perform regular maintenance. Here are a few tips to help you get the longest life possible out of your battery.

Do You Need to Add Water to a Lawn Mower Battery?

Many flooded lawn mower batteries require you to occasionally add distilled or deionized water to help maintain the electrolyte inside. This is because flooded batteries aren't completely sealed and lose water due to evaporation. If your battery has removable caps, you probably need to add water. If you have an AGM or a fully sealed battery, you don't have to add water.

How Do You Add Water to a Battery?

  • Park your lawn mower or tractor on a flat, level surface so that you can gauge the proper water level inside the battery.
  • Make sure that the engine is turned off and has fully cooled.
  • Always wear safety glasses and leather gloves when checking the battery's electrolyte.
  • Use a flat-head screwdriver to pry off the battery caps.
  • The liquid electrolyte should just cover the exposed battery plates (the rectangular metal parts).
  • If the plates are exposed, slowly pour distilled or deionized water into each cell.
  • Add just enough liquid so that the plates are barely covered.
  • Once you're finished, replace the battery caps, pressing them firmly until they pop into place.

What Keeps a Battery Charged on a Lawn Mower?

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. When your battery sits for too long in an undercharged state, crystals will begin to form on the battery's plates, lowering its ability to hold a charge. If you don't plan on using your riding mower or lawn tractor for a month or longer, or if you plan on storing it over the winter, you'll need to maintain the battery charge using a battery charger.

How Do You Know What Battery Charger You Need?

Here are some things to keep in mind when selecting a battery charger for a riding lawn mower:

  • Pick a charger that matches the voltage and chemistry of your battery - if you have a 12-volt flooded battery, the charger must match those specifications.
  • There are 2 types of battery chargers: standard chargers & trickle chargers
  • Standard battery chargers work faster than trickle chargers by delivering a higher constant voltage.
  • Trickle chargers work slower by delivering a much lower charge, which is designed to charge your battery over a longer period of time.

How Long Should You Leave a Battery Charger on a Lawn Mower Battery?

  • When charging your battery, the most important rule is to make sure you do not overcharge it.
  • Automatic chargers and some trickle chargers have a float setting that will shut down the charging process once the battery reaches its ideal voltage.
  • If your battery charge does not have a float setting, you will need to monitor the charger process to make sure that your battery doesn't become overcharged.
  • The length of time it takes to recharge your battery will be determined by how deeply the battery is discharged along with the amperage of the battery charger you're using
  • X2Power battery chargers are perfect for lawn mower batteries. They're available in 0.8 amp, 1.5 amp and 3.8 amp versions and feature a float mode to prevent overcharging.

What is the Most Common Cause of Battery Corrosion?

Lead acid batteries frequently vent sulfuric acid and hydrogen gas during use. These gasses can react with the heat and metal inside the mower's engine to produce a buildup of colorful material called corrosion, which typically appears on the battery's terminals.

Corrosion harms a battery's performance by limiting the amount of power that can travel from the battery to the engine and from the charging system back into the battery. Corrosion is also common when a battery gets older or when it has been overcharged.

How Do You Clean Corrosion Off Battery Terminals?

Should You Take the Battery Out of Your Lawn Mower for the Winter?

Follow these tips to help prolong the life of your lawn mower battery during off-season storage:

  1. Remove the Battery
    Leaving the battery connected for long periods of inactivity can drain it down to nothing, making it impossible to start up again in spring.
  2. Store Your Battery in a Battery Box
    A battery box will help protect your battery from exterior damage. It also keeps it sealed off from corrosive or flammable materials and will collect contaminants in the case of a spill. The NOCO Group U1 Battery Box is sized for U1-size batteries found in most lawnmowers and includes holes to accommodate charger cables.
  3. Charge Your Battery Regularly
    Be sure to place your battery on a charger to maintain its charge.

Have Your Battery Tested for Free at Batteries Plus

If you're having trouble starting up your mower after storing it for the off-season, read our blog "Why Won't My Riding Lawn Mower Start After the Winter?" for more troubleshooting tips. If you still can't get it started, bring the battery to your nearest Batteries Plus and have it tested for free.

Looking for a replacement battery? Our blog entitled "How Do I Know What Kind of Lawn Mower Battery I Need?" will tell you everything you need to know.

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