Allen-Bradley 1747-BA Lithium Battery for SLC 500 5/01 5/02 5/03 Controllers

The Allen-Bradley 1747-BA is a lithium primary battery produced by Rockwell Automation as the designated memory-backup power source for the SLC 500 family of programmable controllers, most specifically the SLC 5/01, 5/02, and 5/03 processor modules. Its function is narrow but vital: while the controller is powered, the application program, data-table values, and configuration reside in battery-backed RAM; when the controller is de-energised, the Allen-Bradley 1747-BA becomes the only thing preserving that content. A failed or missing battery means a controller that comes back from a power outage with a cleared memory and a major fault, forcing the program to be reloaded from archive and the process to be recommissioned from scratch.The Allen-Bradley 1747-BA is built around a 3V lithium-manganese-dioxide (Li-MnO₂) chemistry, delivered in a sealed button/coin-cell format with a capacity commonly cited in the 1500–1750 mAh range depending on the manufacturing lot and whether the cell is supplied as a single unit or in a multi-cell battery assembly. That capacity, combined with the very low quiescent draw of the SLC processor’s memory circuit, typically yields several years of service under normal room-temperature conditions. A low self-discharge rate and a -20°C to +60°C operating range make the Allen-Bradley 1747-BA suitable for the temperature swings found in non-climate-controlled electrical rooms, while the sealed construction prevents leakage that could damage the controller’s battery compartment or PCB. The Allen-Bradley 1747-BA is also used in certain Allen-Bradley CNC/milling control applications where a small, stable, long-life DC source is required, and it is cross-referenced against a wide range of third-party lithium cells — a fact that explains the confusing voltage and chemistry data found in aftermarket listings.

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Description

Technical Specifications

Parameter Name	Parameter Value
Product Model	Allen-Bradley 1747-BA
Manufacturer	Allen-Bradley / Rockwell Automation
Product Type	Lithium Primary Memory Backup Battery
Primary Function	SLC 500 CPU RAM and data-table retention on power loss
Nominal Voltage	3.0 V DC
Chemistry	Lithium Manganese Dioxide (Li-MnO₂), sealed
Typical Capacity	1750 mAh (1500 mAh on earlier/lot-specific cells)
Cell Form Factor	Lithium coin / button cell
Service Life	2–5 years in float service (application-dependent)
Shelf Life	10 years at 20°C
Self-Discharge Rate	< 1% per year at 20°C
Operating Temperature	-20°C to +60°C
Storage Temperature	-40°C to +70°C (10-year shelf life)
Relative Humidity	5%–95% RH, non-condensing
Discharge Type	Continuous low-current (memory hold)
Terminal Type	Integrated connector / flying leads (assembly-dependent)
Enclosure	Sealed, leak-resistant housing
Replacement Indicator	SLC processor “Battery Low” / fault indication
Compatible Platforms	SLC 500 (5/01, 5/02, 5/03), 1746-BAS2, 1746-BAS3
Mounting	Battery compartment or battery backpack in CPU chassis
Safety Standards	IEC 60086, UL 1642
Lifecycle Status	Discontinued by Rockwell; aftermarket equivalents available
Recommended Replacement	Every 2–3 years or on low-battery alarm

Main Features and Advantages

A genuine Rockwell-specified cell: The Allen-Bradley 1747-BA is not a generic lithium coin cell in a branded sleeve. It is specified to the SLC processor’s battery-management and low-battery detection circuitry, so voltage, internal resistance, and termination all report correctly through the controller’s diagnostics. That matters because a mismatched substitute with the wrong voltage or a higher internal resistance can either fail to hold the memory long enough during an outage or, conversely, never register as “low” and run silently until it dies.Long shelf and service life: With a self-discharge rate below 1% per year at 20°C and a stated 10-year shelf life, the Allen-Bradley 1747-BA can be stocked in reasonable quantity without the inventory ageing into unusable stock. In float service inside the controller, the combination of cell capacity and the SLC’s minimal draw gives a practical field life of 2 to 5 years, which is long enough to make replacement a planned maintenance task rather than a recurring emergency.Stable performance across temperature: The Allen-Bradley 1747-BA operates from -20°C to +60°C, a range that covers most electrical-room conditions without derating the cell into unreliability. Its lithium chemistry also holds voltage far more steadily through discharge than alkaline or NiCd alternatives, which means the “battery low” warning appears when the cell is genuinely near end of life rather than because the voltage has sagged under load.Low-risk, high-value spare: At the system level, the Allen-Bradley 1747-BA is one of the lowest-cost components in a SLC installation and one of the most expensive to ignore. Keeping a verified stock on hand turns a potential “memory cleared, process down” event into a routine five-minute swap during a scheduled shutdown.