Install tip: Prolong the life of flooded deep-cycle batteries with regular monitoring

This installation tip was provided by Jeff Myles, marketing manager, Rolls Battery Engineering

Flooded deep cycle batteries are durable and offer exceptional cycle life. To perform at their best, these batteries should be cycled regularly and charged at the proper voltage and adequate charge current. These conditions may not always be met as the charge source — often a solar array — may not generate sufficient power to bring the battery bank to a full state of charge. Over time, deficit cycling and inadequate charge current can cause an imbalance of charge, loss of capacity and possible cell failure.

The approximate state of charge at various specific gravities at 25° C (77° F).

To avoid these situations, it’s important to regularly monitor the condition of the batteries. The best method is to test and track the specific gravity in each cell using a standard hydrometer or refractometer. These readings will provide an indication of state of charge as well as any charge imbalance, cell failure or sulfation. Adjustments to charge voltage and charge time may be necessary as seasons and daylight hours change throughout the year.

Testing specific gravity will provide confirmation that the battery bank has reached full charge, indicate that all batteries in the bank are balanced and charging evenly, identify weak or failed cells that are no longer accepting a charge and determine if a corrective equalization is necessary.

Loss of capacity, charge imbalance and low specific gravity readings are indicators of sulfation. Periodically, a controlled overcharge may be used to balance each cell in the battery bank and remove any sulfation build-up. This maintenance procedure is referred to as a corrective equalization, and frequency will vary by system due to factors such as operating temperature, frequency of cycling and depth of discharge.

Many charge controllers offer schedules or automatic preventative equalizations. Rolls Battery recommends performing this step only as required to prevent unnecessary deterioration of oxide paste in balanced, healthy cells. Always refer to the battery manufacturer’s recommendations for charging, care and maintenance.