What is sulphation and how do I prevent it?

Lead sulphate crystals forming on the plates during discharge, which fail to convert back on charge if the battery is left discharged or is chronically under-charged. It is probably the single largest killer of lead-acid batteries in the field. Prevention: recharge promptly after discharge, avoid deep discharges where the design does not call for them, and ensure the charger delivers a correct and complete charge rather than a partial one.