"A Few Words About Industrial Batteries"
The modern industrial lead-acid battery is ruggedly built and with reasonable care will give many years of service. Normal battery life is 5 to 7 years or 1500 to 2100 charge/discharge cycles. Your industrial battery represents a sizable investment that will not be fully recovered if its useful life is drastically shortened. This can happen through neglect or poor operating practices. Three of the batteries worst enemies are : Overcharging/undercharging, Low electrolyte level, and Deep discharge cycles.
Overcharging and/or poor maintenance can be causes of low electrolyte level. Excessively low electrolyte level causes a portion of the plates to become exposed. The result is overheating and damage to the active material on the positive plates. Consistent undercharging can cause residual sulfation because not all of the active material is being returned to the positive plates on each charge. Although theses conditions can lead to premature failure, deep discharge is potentially the most damaging. The result is decreased ampere-hour capacity, shortened life (fewer charge/discharge cycles), increased internal resistance (decreased efficiency) and increased chance of shorted cells.
Deep discharge for most batteries means going below 1.140 specific gravity or 1.70 volts/cell, and is caused by continuing to draw energy from a battery that has reached its discharge limit. During deep discharge, too much of the active material (lead peroxide) leaves the positive plates and not all of it returns during charging. This reduces the effective plate area. Over time, the lost active material stays in the electrolyte or ends up in the bottom of the cell jars as lead sulfate. It is now "out of action" and does not contribute to the batteries ability to store energy. It piles up and may contact the plates causing a shorted cell and loss of energy. A severely sulfated battery must be replaced because it: will not hold a charge, will not last a full 8 hour shift, costs more to charge, uses excessive water and has increasing repair costs.
Proper Battery Care
Proper selection and care of your battery will help ensure that it will have a long and productive life. Make sure that the battery is adequately sized for the application. An undersized battery will overheat from high current draw and may not last through a full 8 hour shift.
Over time, cells can become unequally charged. An occasional equalizing charge will help correct cell-to-cell imbalances.
Starting charge rates should not exceed 25 amps per 100 A.H. of capacity. Finish rates should be about 5 amps per 100 A.H. of capacity. Make sure that the cell voltage stabilizes at 2.37 volts/cell during the last 2 hours of finish rate charging. Check the electrolyte level, cell voltages and S.G. frequently. Keep a record of the maintenance performed on each battery.
Above all, avoid discharge below 1.140 specific gravity! If in doubt, check the battery manufacturer's recommendations for proper charging rates and discharge limits for your battery. One of the best ways to prevent over discharging is to add a battery gauge and/or lift interrupt circuit. Next time we will look at several common battery protection devices, how they work and how the interupt lift circuits help ensure proper vehicle battery maintenance.
Excerpts from the Flight Systems' Model 204 Instructional Manual