Signs of a Dead Battery in a Craftsman Lawn Mower

If the engine on your electric-start Craftsman mower doesn’t turn over and start, the first thing to check out is the battery. Craftsman mowers equipped with electric starters rely on a lead-acid storage battery to power the starter. Over time, chemical or physical changes may impede the battery’s ability to take a charge that enables it to produce enough electricity to turn over the engine, and the battery is declared dead.

A visual inspection of your mower battery may reveal a physical flaw that’s responsible for the failure to produce electricity. Open the battery compartment. Look for problems such as a broken battery terminal or bulge in the case. Inspect the outside for holes, cracks or discoloration in the plastic case. Also check for signs of burning, melting or excessive leaking. If the battery has removable caps, unscrew them and look in the holes with a flashlight. There should be clear fluid in each cell. If the fluid in any cell is dark or brown or stinks like rotten eggs, the battery is bad. If there’s no visible fluid, the battery may have gone dry.

The battery’s voltage level can point up internal problems with the battery. Test the battery’s voltage with a digital volt meter after giving it a full charge. If the battery voltage reads between 12.7 V and 13.2 V, it is probably OK. If the battery reads zero volts, there is an internal short. If the reading is 10.5 V or less, the battery has a dead cell. If the reading is 12.4 V or less, the battery is sulfated. That means the plates cannot accept a charge because they are covered with sulfate crystals that have chemically locked up the elements needed to produce electricity.

Another battery check is called a load test. This test is performed on a warm day above 50 degrees Fahrenheit with the battery installed in the mower. First, charge the battery overnight. Then connect the leads from a digital volt meter to the correct battery terminals and crank the engine for 30 seconds while watching the voltmeter reading. A good battery will hold steady at about 10 volts through 30 seconds of constant cranking. If the battery voltage steadily drops while you crank the engine, or the voltage drops to zero the instant you try to crank the engine, you have a bad battery.

If your battery tests as bad, disconnect the black minus or negative cable first and pull it away from the negative battery terminal, being careful not to touch it to metal. Next, disconnect the red plus or positive cable and pull it away from the battery. Undo any clamp or holder and pull the bad battery out of the mower. Buy a replacement battery that matches the bad battery. Install it by performing the removal steps in reverse.

Keeping a lead-acid lawn mower starting battery fully charged between uses and avoiding deep discharges are the keys to prolonging battery life. Don’t deeply discharge a starting battery by running it down until it won’t turn over your engine. Always recharge it after you are done mowing for the day. Use a "smart" charger that can detect when the battery is fully charged and turns itself off. When storing a battery for long periods, charge it before storage and recharge it at least once every six months to prevent sulfation. Never store a discharged battery.