Rockwell Automation 1756-L6x_L7x ControlLogix System User Manual - Manual (Page 73)

Rockwell Automation Publication 1756-UM001O-EN-P - October 2014 73
Start Using the Controller Chapter 3
1756-BA1 or 1756-BATA Battery Life
To estimate how long a 1756-BA1 or 1756-BATA battery can support controller
memory on 1756-L6
x, series A controllers, perform this procedure.
1. Determine the temperature 2.54 cm (1 in.) below the chassis.
2. Determine the weekly percentage of time that the controller is turned on.
3. Determine the estimated worst-case battery life before and after the BAT
status indicator turns on.
4. For each year of battery life, decrease the time before the BAT status
indicator turns on by the percentage that is shown in the table.
Do not decrease the time after the BAT status indicator turns on.
IMPORTANT: To prevent possible battery leakage, even if the BAT status
indicator is off, replace a battery according to this schedule.
EXAMPLE If a controller is Off at one of these times:
• 8 hr/day during a 5-day work week
• All day Saturday and Sunday
Then the controller is off 52% of the time:
• Total hours per week = 7 x 24 = 168 hrs
• Total off hours per week = (5 days x 8 hr/day) + Saturday +
Sunday = 88 hrs
• Percentage off time = 88/168 = 52%
IMPORTANT If the BAT status indicator turns on when you apply power to the
controller, the remaining battery life can be less than
Table 7 indicates.
Some of the battery life can be used up while the controller is off and
unable to turn on the BAT status indicator.
If the temperature 2.54 cm (1 in.)
below the chassis is Replace the battery within
-25…35 °C (-13…95 °F) No replacement required
36…40 °C (96.8…104 °F) 3 years
41…45 °C (105.8…113 °F) 2 years
46…50 °C (114.8…122 °F) 16 months
51…55 °C (123.8…131 °F) 11 months
56…70
°C (132.8…158 °F)
8 months