Properly initializing your deep-cycle battery bank is key to system success. To start with, deep-cycle batteries may not be fully charged when received. Self-discharge during transit and storage is normal. The amount of discharge varies due to storage time and ambient temperature. It is safe to assume, however, that batteries will need a refresher charge during installation.
Whether installing flooded, maintenance-free AGM or GEL models, battery banks should be placed on an initial balance charge using manufacturer-recommended charging parameters prior to cycling. This ensures each battery is fully charged and will cycle in balance with the rest of the bank. Recommended charging parameters may be unique to the brand and different battery types. Inverters and charge controllers are often pre-programmed with default set points that may not meet these specifications. Always refer to the manufacturer’s recommended voltage settings and adjust as required.
Electrolyte levels in flooded batteries should be checked prior to an initial charge to confirm the plates in each cell are fully covered. It is normal for electrolyte levels to drop slightly in some models as the battery case relaxes. In cells with low electrolyte levels, add distilled water until all plates are covered completely. It is important not to overfill cells as liquid levels will rise slightly during charging.
Specific gravity is the best indicator of a flooded battery’s relative state of charge, as well as overall health. Specific gravity readings are obtained with a hydrometer. Readings should be taken when the battery bank has completed charging and is resting in a float charge. Periodically, you may note specific gravity readings that vary between battery and/or cell, or are consistently low. This is often the result of insufficient charge current, deficit cycling and/or sulfation build-up. Performing a corrective equalization on the bank will help properly balance and desulfate the battery bank, prolonging its life. Follow the manufacturer’s recommendations to complete this as part of a maintenance routine. Many systems allow programming of equalization charges on a set schedule. Be cautious of this. Frequently running a high voltage charge on healthy cells may cause them to burn out prematurely.
This tip was contributed by Jeff Myles, marketing manager, Surrette Battery Company, manufacturer of Rolls Battery.