Identify the battery design
Flooded lead acid, AGM, gel, and lithium deep cycle batteries have different charging and service requirements. Use the label and manufacturer documentation as your starting point.
Look at how the battery has been used
Repeated deep discharge, long periods in a low state of charge, heat, and unsuitable charging can shorten service life. Usage history helps explain why capacity has fallen.
Test before attempting recovery
Check physical condition, resting voltage, charging behavior, and capacity with methods suitable for the battery. A single voltage reading cannot tell the whole story.
Use chemistry appropriate methods
Never apply a lead acid reconditioning procedure to a lithium battery. Sealed battery designs also have service limits that must be respected.
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