This article is a Allen-Bradley SLC 500 Battery.
The RTC battery on the Allen-Bradley SLC 500 is used to retain program status (such as RTO Retentive Timer and PLC date/time). The program itself will not be lost as it is written in a none-volatile memory.
Below are picture of what the Allen-Bradley SLC 500 battery looks like. Note that some vendors will sell you the battery only and you are left to solder the batter leads. Please do not try to solder the battery leads yourself. Batteries that are exposed to high temperature (such as soldering iron) are known to explode.
Below are pictures of where the battery will be installed on the Allen-Bradley SLC 500 CPU board.
If the battery is pulled out or if it is below the low threshold (of 2.0VDC), and NVRAM error is issue (Error Code 0001x; in Hex).
The Status File function can be used to monitor the status of the RTC battery using the S:5/11. This bit will be ON when the Battery Low LED is ON.
Table below is from Allen-Bradley SLC 500 Instruction Set – Reference Manual (Page 544).
Picture below shows the SCL 5/03 CPU faceplate where the RTC battery voltage is below its low voltage threshold. FLT (Fault) LED and BATT LED is lighted (ON).
The picture below shows a good RTC battery where the FLT (Fault) LED and BATT LED is not lighted (OFF)
Below is a specification the Allen-Bradley SLC 500 battery.
- SANYO – Part No SANYO CR14250SE
- 3.0V nominal voltage
- 850mAh nominal capacity (end discharge of 2.0V when battery allowed to discharge at a standard current level @ 23oC (73oF))
- 0.5mA standard discharge current
- 7mA maximum continuous discharge current (50% of nominal capacity obtained with end voltage of 2.0V @ 23oC (73oF))
- 70mA maximum pulse discharge current (2.0V cell voltage when 15 second pulse applied at 50% discharge depth @ 23oC (73oF))
- Dimensions: 14.5mm dia. x 25.0mm lg.