Explanation: Lead-acid batteries, particularly those in critical standby applications like GMDSS, require periodic "equalization charges" to maintain optimal health. When continuously float charged, lead-acid batteries can develop electrolyte stratification and sulfation on the plates, reducing capacity over time. An equalization charge is a controlled overcharge at a higher voltage, typically reaching the battery's gassing range (around 2.45-2.50V per cell). This process mixes the electrolyte, prevents stratification, and helps reverse sulfation, restoring the battery's full capacity. A fully automatic GMDSS-compliant charger is designed to safely administer this high charging rate. Performing this weekly ensures the battery remains in peak condition, vital for emergency operations. Daily high charging (A) is excessive and harmful, leading to premature battery degradation. Never using a high charging rate (C) would neglect essential maintenance, causing sulfation and stratification. While reaching 2.5V/cell (B) is part of the process, a weekly frequency is generally considered more appropriate for critical GMDSS batteries than monthly to prevent issues before they become severe.