Lamar Technologies CA 1550 - Manual (Page 16)

4. OPERATING GUIDE - DISCHARGING
40 amperes. From Figure 4-1, it is observed that at the end of 1 hour of discharge
time, the battery voltage has reduced only to about 22 volts. Because the minimum
required cutoff voltage is 18 volts at the 1-hour discharge rate, the battery exceeds the
minimum requirements. With increasing hours of use or age, the battery
capacity decreases. Therefore, battery manufacturers usually recommend testing for
a capacity equal to 80% of the original ampere-hour rating.
Figure 4-1. Typical discharge curve for 40 ampere-hour lead-acid aircraft
battery
Figure 4-2 illustrates discharge curves for typical SLABs at different discharge
rates. Note that the cell voltage drops much more rapidly at the higher discharge
rates, i.e. the rates at which a greater current is drawn during a shorter period of
time.
CA-1550 CHARGER / ANALYZER - OPERATING MANUAL V1.2 Page 14