An electric-start riding lawn mower requires a battery to power the ignition and electrical systems present on the lawn mower. If this battery will not hold a charge, you may wish to inspect a few items before going out to purchase a new battery.
If the battery cables are broken, frayed, or corroded, the lawn mower will not adequately charge the battery. Likewise, the battery cannot provide enough electrical current to start the lawn mower. Since either condition may mimic a bad battery, inspect the battery cables for damage and replace if necessary.
Battery Electrolyte Levels
Most lead-acid batteries employ a vent system so that the battery is relieved of gas pressure when the battery heats up. Over time, the battery will vent enough gas that the electrolyte level may become low. To correct this condition, remove the top battery vents when the battery is cool, and add distilled water to each battery cell that has an electrolyte level below the “fill” line.
Lawn Mower Charging System
A lawn mower electrical system is designed to provide enough power to operate the lawn mower with a small amount of electrical power left over to charge the battery. However, if the electrical system does not produce enough power to operate the mower, it will take the extra power from the battery. Examine the lawn mower electrical system by starting the lawn mower up, and then removing the battery. If the lawn mower turns off after the battery is disconnected, the lawn mower electrical system is the culprit. If this is the case, have a mechanic or automotive technician examine the lawn mower.
Lawn and garden lead-acid batteries are designed for six months to two years of use. If the battery is more than one year old and does not hold a charge, the battery may be replaced.