The lawn mowersmall engine often has a separate model number. Use the small engine model number for a complete list of symptoms and parts. Watch our model # lookup video for help finding the model number.
The part(s) or condition(s) listed below for the symptom Lawn mower battery keeps dying are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
One or more cells in the battery may be dead. Try charging the battery with a battery charger. If the battery still won't hold a charge, this indicates that the battery is defective and will need to be replaced.
To determine if the charger is defective, use a multimeter to test the charger for continuity. In addition, test the outlet used by the charger, and ensure that the outlet has not tripped a breaker.
The alternator provides voltage to the lawn mower while the engine is running and also recharges the battery. To determine if the alternator is defective, use a multimeter to test the alternator voltage output according to the wiring diagram.
While the engine is running, the voltage regulator sends the proper amount of voltage from the alternator to the battery to keep the battery charged. If the voltage regulator is defective, the battery won't receive enough voltage, causing the battery to drain quickly.