Yes, a dead lawn mower battery can be recharged. First, it is important to determine the type of battery in your lawn mower. Lead-acid batteries are typically used in smaller models and can be recharged with an external charger or by running the engine until it begins to charge on its own. Lithium-ion batteries are more commonly found in larger models and must only be recharged with an external charger as they cannot self-charge from the engine. Once you have identified the type of battery being used, charging should begin with a low voltage setting for about 15 minutes before gradually increasing if needed. It's also important to check that all connections are securely tightened during this process to ensure maximum efficiency when charging your dead lawn mower battery.