How do I store a riding mower battery for the winter?

Take it out, charge it, keep it cool

The best way to get a riding mower battery through the winter is to take it off the mower, charge it fully and keep it somewhere cool and dry. Husqvarna's storage steps say to remove the battery, then clean, charge and store it in a cool place, but protect it from direct cold.^[2] Briggs & Stratton says to disconnect the negative battery cable, remove the battery and store it in a cool, dry place.^[3]

That routine matters because a battery left in a cold shed slowly loses its charge, and a flat battery is much harder to bring back than one that was kept topped up. Spend twenty minutes in the fall and spring starts easily.

Safety first

Explosive gases from a battery can cause death or serious injury, so keep open flames, sparks and smoking materials away from it.^[1] Battery fluid contains sulfuric acid, and contact with skin, eyes or clothing can cause severe chemical burns, so wear safety glasses and protective gear near the battery.^[1]

When you take the cables off, disconnect the grounding cable first and reconnect it last.^[2] Do not let a wrench or other object touch both terminals at the same time.^[2] Do not tip the battery beyond a 30 degree angle in any direction.^[1]

Clean it before it goes on the shelf

Dirt and corrosion on the case and posts make a battery bleed power slowly, so clean it before storing it. Rinse the battery with plain water and dry.^[2] Clean the terminals and battery cable ends with a wire brush until shiny, then coat the terminals with grease or petroleum jelly.^[2] Briggs & Stratton's version is to clean the battery terminals using a terminal cleaner, and coat all terminals with a terminal protector.^[3] Both are sold at auto parts and hardware stores.

Charge it all the way

Charge before storage, not after. Use an automotive charger on the low setting. Ariens says to recharge at 6 to 10 amperes for 1 hour.^[1] Periodic charging of the battery with an automotive charger will extend its life.^[1] If the fluid is frozen, remove the battery from the unit and let it thaw before charging.^[1]

A multimeter tells you when it is done. Husqvarna's chart shows 12.6 volts as a full charge.^[2] Husqvarna's chart puts 12.4 volts at 75 percent charge, 12.2 volts at 50 percent, 12.0 volts at 25 percent and 11.8 volts at 0 percent.^[2]

Where to keep it

A shelf in a cool, dry garage or basement is fine. Keep it upright and away from the fuel can and the furnace, and away from anything that could touch both posts. Keeping it off the mower also keeps it away from a key left on and a stray switch. If your garage freezes, a heated space or a spot inside the house, such as a basement shelf, protects it from direct cold.

Mower storage generally is a good moment to look at the rest of the machine. Ariens warns never to store the unit outdoors,^[1] so the mower itself should be under cover.

Check on it over the winter

Once or twice before spring, check it. Put the multimeter on it, or connect the charger for a while. Some mowers can use a trickle charger for the job: the Ariens charging system has a port for a trickle charger on the wiring harness to the right of the starter solenoid, and the charger maker's instructions apply to that port.^[1] If your mower has a port like that, check your owner's manual first.

In spring, put it back the other way: seat the battery, connect the red cable first and the black cable last, and tighten both so they cannot move.^[2]

If it does not survive

If a stored battery will not charge, or will not hold 12.6 volts after charging, it is worn out. Do not throw it away. It is unlawful in Virginia to put a used lead acid battery in the household trash or otherwise throw it away, other than by delivering it to a battery retailer or wholesaler, a secondary lead smelter, or an authorized collection or recycling facility.^[4] Most places that sell batteries will take the old one.

Stop and call a pro if

• The case is cracked, swollen or leaking. Do not charge or move it more than you must, and wear gloves and safety glasses.
• A cable or terminal is melted or burned. Have the wiring checked before the new season.
• A fully charged battery goes flat again within days. Read why a riding mower battery will not hold a charge.
• The mower still will not start with a good battery. See why a riding mower clicks but does not start.

Getting help in Virginia

For the rest of your spring routine, read how to change the oil in a riding mower and see how much riding mower repair costs in Virginia. Browse more lawn equipment repair answers or lawn care and mower businesses near you.

When you are ready, describe the problem once and local mower repair shops quote it.