Simplex 4008-9101 - Page 82

A-2
7. If either the Standby Current or the Alarm Current is greater than the C/20 current for the initial battery size selected, a
Discharge Factor (DF) must be applied. For example, 1 A load on a 10 Ah battery requires a Discharge Factor of 1.08 (10
Ah / 1 A gives discharge time of 10 hours; DF = 1.08). Use the following table to determine Discharge Factor (use the 20
hr value for 24 hr standby):
8. Standby Discharge Factor (SDF) = _________ Alarm Discharge Factor (ADF) = _________
9. Minimum Required Battery Capacity Calculation. (to account for battery aging, a 1.17 multiplier is included)
Minimum battery capacity in Ah =
1.17 x [(A x C x SDF) + (0.0167 x B x D x ADF)] = _______
10. If the battery size initially selected is smaller than the result of step 9 above, repeat the calculations using a larger battery
size.
20 Hour Rating C/20 (Amps) 20 Hour Rating C/20 (Amps)
2.2 Ah 0.11 7.0 Ah 0.35
3.0 Ah 0.15 7.2 Ah 0.36
3.4 Ah 0.17 10 Ah 0.50
4.0 Ah 0.20 12 Ah 0.60
4.5 Ah 0.225 12.7 Ah 0.635
5.0 Ah 0.25 18 Ah 0.90
6.2 Ah 0.31 25 Ah 1.25
Discharge
Time
Discharge
Factor
Discharge
Time
Discharge
Factor
Discharge
Time
Discharge
Factor
Discharge
Factor
0.083 hr 5 min 3.85 2 hr 1.43 8 hr 1.10 14 hr 1.03
0.166 hr 10 min 2.78 3 hr 1.30 9 hr 1.09 16 hr 1.02
0.249 hr 15 min 2.27 4 hr 1.22 10 hr 1.08 18 hr 1.01
0.332 hr 20 min 2.08 5 hr 1.18 11 hr 1.06 20 hr 1.00
0.5 hr 30 min 1.96 6 hr 1.14 12 hr 1.05 48 hr 1.00
1 hr 60 min 1.67 7 hr 1.11 13 hr 1.04 60 hr 1.00
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