In a normal operating environment, which condition maximizes the lifespan of lead-acid batteries?

The condition that maximizes the lifespan of lead-acid batteries is avoiding full discharge. Lead-acid batteries are designed to operate within a specific depth of discharge, and regularly discharging a lead-acid battery to low levels can lead to sulfation, where lead sulfate crystals develop on the electrodes. This sulfation process can decrease the battery's capacity and efficiency over time. By avoiding full discharge, the active material in the battery remains more accessible, helping to maintain the chemical balance within the cells and prolonging the overall lifespan of the battery.

While other factors like charging voltage and temperature also impact battery longevity, they are not as critical as maintaining a proper depth of discharge. Consistent high charging voltages, extreme temperatures, or full discharges can lead to quicker wear or performance degradation. Hence, keeping the battery from a full discharge state serves as a primary strategy to ensure its durability and reliable performance.