Allen-Bradley 16#0011: Allen-Bradley CompactLogix Error C...

Symptoms

The controller's OK LED remains green but a minor fault is logged. The battery backup voltage is low, indicating that the battery needs replacement. The controller continues to operate normally.

Possible Causes

Battery has reached end of life
Battery was not replaced after the low battery warning
Battery contact corrosion or loose connection
Extended power-off period drained the battery

Troubleshooting Steps

Step 1: Check the minor fault log in Studio 5000 for the battery low warning
Confirm the fault is a low battery warning (type 16#0011)
Step 2: Power down the controller and locate the battery compartment
Battery is accessible for replacement
Step 3: Remove the old battery and install a new one of the same type
New battery is installed with correct polarity
Step 4: Clear the minor fault in Studio 5000
Battery fault is cleared and no new battery warnings appear

How to Reset

To reset: 1) Replace the controller battery with a new one. 2) Clear the minor fault in Studio 5000 via Controller Properties > Minor Faults. Caution: Replace the battery while the controller is powered to avoid losing volatile memory contents.

Common Replacement Parts

1747-BA: Controller backup battery (Replace with the same catalog number; do not use substitutes)

Frequently Asked Questions

Q: How often should I replace the PLC battery?
Typically every 2-3 years, but follow the manufacturer's recommendation. Replace proactively when the low battery warning first appears.
Q: What happens if the battery dies completely?
The controller will lose its retained memory contents, including timer and counter accumulated values, when power is removed.

Allen-Bradley CompactLogix Error Code 16#0011