Maintenance requirements vary by battery chemistry and configuration. Additionally, some maintenance tasks, such as adding water or equalization, require on-site manual operations and/or oversight, while charge regulation, voltage checks and related measurements can be automated via sophisticated charge controllers or battery management systems, which are a de facto requirement for lithium-ion batteries.
Sealed lead-acid batteries, gel cells and AGM (Absorbed Glass Mat), are often referred to as maintenance-free because they don’t require watering or an equalization charge. This makes them well-suited for remote or unattended power systems. However, sealed batteries require accurate regulation to prevent overcharge and over-discharge.
Lead-acid batteries should always be recharged as soon as possible. The positive plates change from lead oxide, when charged, to lead sulfate, when discharged. The longer they remain in the lead sulfate state, the more of the plate remains lead sulfate when the battery is recharged. The portion of the plates that become “sulfated” can no longer store energy. Batteries that are deeply discharged and then only partially charged on a regular basis often fail in less than one year (except those with nano-carbon). Always use temperature compensation when charging batteries to prevent over or under-charging. NOTE: Battery warranties do NOT cover damage due to poor maintenance or loss of capacity from sulfation.
Check the electrolyte level in wet-cell, or “flooded” batteries, at least once every three months and top-off each cell with distilled water. Do not add water to discharged batteries! Electrolyte is absorbed when batteries are discharged, so if you add water at this time and then recharge the battery, electrolyte will overflow and create a safety hazard. Keep the tops of your batteries clean and check that cables are tight. Do not tighten or remove cables while charging or soon after charging! Any spark around batteries can cause a hydrogen explosion inside the case and potentially ignite a fire or an even larger explosion if the batteries are not properly vented.
An “equalization” charge should be performed on flooded batteries whenever cells show a variation of 0.05 or more in specific gravity from each other. This is a long steady overcharge, bringing the battery to a gassing or bubbling state. Do not equalize VRLA batteries!
With proper care, lead-acid batteries will have a long service life and work very well, in almost any power system.
Always use extreme caution when handling batteries and electrolyte (sulfuric acid). Wear appropriate personal protective equipment, including electrical- and chemical-resistant gloves with sleeves, goggles, and acid-resistant clothing. “Battery acid” will instantly burn skin and eyes and destroy cotton and wool clothing. Similar precautions apply to other battery types – always read and adhere to manufacturer safety recommendations when handling batteries. For any type of battery, be sure to remove any metal jewelry and avoid shorting the battery terminals.