Allen-Bradley 1756-BA2 — ControlLogix Battery Buying Guide

By Abdullah Zahid
14 min read
Allen-Bradley 1756-BA2 lithium battery assembly for ControlLogix 1756-L6x Series B PLC controllers

Allen-Bradley 1756-BA2 Lithium Battery Assembly: Specs, Compatibility & Procurement Guide for ControlLogix 1756-L6x Series B

If you are managing a ControlLogix-based plant and a "battery low" warning has appeared on a 1756-L6x Series B CPU, or you are building out a preventive maintenance spares kit, the Allen-Bradley 1756-BA2 is the OEM-specified lithium battery assembly you need. At 3 V DC with a typical capacity of approximately 1200 mAh, it provides backup power for controller memory and the real-time clock whenever the ControlLogix chassis loses supply voltage. The critical qualifier is series: this battery is specified for 1756-L6x Series B controllers, not all ControlLogix generations.

If you have already confirmed your CPU catalog number and series, check current pricing and availability for the Allen-Bradley 1756-BA2 at LeadTime.ca — ships worldwide.

Who Should Buy the Allen-Bradley 1756-BA2 — and Who Should Not

The 1756-BA2 is the right battery for your application if all of the following are true:

  • Your CPU catalog number is a 1756-L6x Series B controller — confirmed on the nameplate.
  • You need the OEM assembly with the correct plug-in connector and wire leads for the ControlLogix chassis battery slot.
  • Your plant or OEM standards require genuine Allen-Bradley components to maintain warranty and support standing.
  • Your control cabinet operates within a temperature range around 0 to 35 °C for rated battery service life.
  • You require a part that is regularly stocked by Rockwell Automation distributors for short lead times.

If your controller is a different ControlLogix generation, a CompactLogix platform, or a controller that uses integrated nonvolatile memory and does not require a backup battery, the 1756-BA2 is not the correct part. Check Rockwell documentation for your exact catalog number and consider the 1756-BA1 or other 1756-BAx variants as applicable to your specific CPU.

On this page:

What the Allen-Bradley 1756-BA2 Actually Does in a ControlLogix System

The Allen-Bradley 1756-BA2 is a 3 V DC lithium metal battery assembly assigned by Rockwell Automation as the OEM backup battery for ControlLogix 1756-L6x Series B CPUs. Its function is specific and non-negotiable in an uninterruptible power strategy: when the ControlLogix chassis loses AC or DC supply, the 1756-BA2 maintains the controller's nonvolatile memory and real-time clock. Without it, a power interruption can mean a cold-start controller with no program, no clock data, and a production line that cannot resume until an engineer reloads and verifies the application.

This is not a generic coin cell. The 1756-BA2 is a complete assembly with wire leads and a plug-in connector engineered to the physical and electrical interface of the ControlLogix 1756-L6x Series B chassis battery slot. Typical capacity is approximately 1200 mAh, and the battery is rated for a minimum service life when maintained within an operating temperature range of 0 to approximately 35 °C. Exposure to higher ambient temperatures directly reduces the usable battery life, which is why cabinet thermal management matters as much as replacement scheduling.

The battery belongs to the ControlLogix 5560 product family. It is not a programmable component and it draws no current from the I/O bus — its sole job is to hold memory and clock state during outages. That simplicity is also what makes it easy to overlook until a fault appears on the front panel.

Where the 1756-BA2 Fits in a Typical ControlLogix Architecture

The 1756-BA2 sits inside the ControlLogix chassis, connected directly to the 1756-L6x Series B CPU module. It is one of the last components in the power delivery chain but one of the first you should think about in a maintenance plan.

  • Main power supply feeds the ControlLogix chassis backplane and all installed modules including the CPU.
  • The 1756-L6x Series B CPU module handles program execution, I/O scanning, and communications under normal powered conditions.
  • The 1756-BA2 battery assembly connects to a dedicated battery port on the CPU module via the plug-in wire harness.
  • When chassis power is removed, the 1756-BA2 assumes responsibility for the CPU's memory backup and real-time clock independently of any other module in the rack.
  • Downstream I/O modules, communication modules, and remote racks are not affected by the battery; only the CPU's internal state depends on it.

Typical Applications for the Allen-Bradley 1756-BA2

Discrete manufacturing plants running ControlLogix 1756-L6x Series B CPUs represent the core market for the 1756-BA2. Automotive body shops, packaging lines, and material handling systems with large ControlLogix controller fleets typically include 1756-BA2 units in their annual preventive maintenance spares orders, replacing batteries during scheduled shutdowns before a low-battery fault forces an unplanned intervention.

Process industries — oil and gas, water and wastewater treatment, chemical processing — rely on ControlLogix DCS architectures where controller uptime is critical. In these environments, a failed backup battery is not a minor inconvenience; it is a compliance and safety issue if a program must be reloaded during an active process. Emergency replacement after a battery low warning is a common scenario in these facilities, and distributor stock levels matter significantly in that context.

OEM machine builders shipping equipment pre-loaded with ControlLogix 1756-L6x Series B CPUs often include 1756-BA2 assemblies in commissioning kits. Panels frequently ship with the battery disconnected for transport safety, and the installation technician connects and verifies the battery during site commissioning before handover. Spare parts kits for exported machines destined for North America and international sites commonly include at least one 1756-BA2 as a first-year maintenance item.

Application Typical Deployment
Automotive manufacturing Preventive replacement across fleet of 1756-L6x Series B CPUs during planned shutdowns
Packaging and material handling Emergency replacement after battery low fault on production PLC
Oil and gas / chemical process Spares stocked at site to support critical ControlLogix DCS architecture uptime
Water and wastewater treatment Scheduled battery maintenance to maintain program and clock retention during outages
OEM machine builders Commissioning battery installation and spare parts kits for machines shipped with ControlLogix
MRO and spare parts planning Stocking 1756-BA2 as a consumable line item in plant-wide Rockwell Automation parts inventory

Specifications and Variant Comparison: 1756-BA2 vs Other ControlLogix Batteries

Parameter Value Notes
Battery type Lithium metal battery assembly OEM Allen-Bradley / Rockwell catalog 1756-BA2
Nominal voltage 3 V DC Backup power for ControlLogix 1756-L6x Series B
Typical capacity Approx. 1200 mAh Capacity depends on cell and operating conditions
Termination Wire leads to plug-in connector Designed for ControlLogix chassis battery port
Compatible controllers ControlLogix 1756-L6x Series B CPUs Confirm exact catalog number and series on nameplate
Product family ControlLogix 5560 OEM battery assembly
Recommended operating temp (life rating) 0 to approx. 35 °C Higher temperatures reduce battery service life
Short-term storage temp range Approx. -45 °C to +85 °C Limited duration — follow Rockwell storage guidelines
Approximate dimensions (battery body) Approx. 0.68 in x 1.38 in Assembly includes leads and connector
Approximate weight Approx. 36 g For handling and shipping planning

Full technical specifications are available on the product page at LeadTime.ca.

Battery Model Intended Controller Family Voltage Key Difference vs 1756-BA2
1756-BA2 ControlLogix 1756-L6x Series B 3 V DC This listing — OEM assembly with correct connector for 1756-L6x Series B
1756-BA1 Other 1756-BAx compatible controllers 3 V DC Different variant — confirm your CPU catalog and series before substituting
Other 1756-BAx variants Other ControlLogix generations Varies Not interchangeable — check Rockwell documentation for your exact CPU
Third-party cross-reference Marketed as 1756-BA2 equivalent 3 V DC (nominal) Connector and lead configuration must be independently verified before use

If your controller nameplate shows a catalog number outside the 1756-L6x Series B family, the 1756-BA2 is not the correct selection — check current availability and confirm compatibility at LeadTime.ca before placing your order.

Expert Verdict: Is the Allen-Bradley 1756-BA2 the Right Battery for Your Plant?

For any operation standardized on ControlLogix 1756-L6x Series B controllers, the 1756-BA2 is the straightforward, low-risk choice. The OEM assembly eliminates guesswork around connector fit, electrical compatibility, and controller diagnostics — all of which become expensive problems to sort out when a battery low warning appears during a production shift. With a nominal voltage of 3 V DC and approximately 1200 mAh capacity, the 1756-BA2 is specified precisely for the memory backup and real-time clock function this CPU family requires. Maintenance teams who want a part that installs, connects, and clears faults as documented — without a compatibility investigation — are exactly who this battery is built for. The same is true for MRO planners building spares kits and OEM builders shipping pre-loaded ControlLogix panels.

Where the 1756-BA2 is not the right answer is equally important to understand. If your site runs ControlLogix generations outside the 1756-L6x Series B range, you need to confirm the correct 1756-BAx variant from Rockwell documentation — the 1756-BA1 and other variants are not one-to-one replacements. CompactLogix platforms have their own battery requirements entirely. And if your organization is migrating to newer controller architectures that use integrated nonvolatile memory and eliminate battery dependency, that design decision removes the 1756-BA2 from the equation permanently. For budget-sensitive applications where OEM is not mandated, third-party equivalents exist, but the connector and lead configuration must be independently verified before installation — an assumption that the cross-reference is physically and electrically identical has caused real commissioning failures in the field.

From a procurement standpoint, the 1756-BA2 benefits from being a well-established consumable in the Rockwell distribution network. Rockwell Automation lists a standard lead time for this catalog number, and major North American distributors describe it as a regularly stocked item — meaning emergency replacement scenarios are usually serviceable quickly when you are sourcing through the right channel. A specialist automation distributor can confirm compatibility against your CPU nameplate before the order ships, validate that the assembly you receive matches current Rockwell specifications, and provide current lead-time data that reflects actual regional stock rather than a theoretical lead time. View current pricing and stock status for the Allen-Bradley 1756-BA2 at LeadTime.ca — available for order worldwide.

For volume pricing on fleet-wide battery replacements or to confirm lead time before committing to a maintenance schedule, contact the LeadTime.ca team directly — we ship worldwide.

What Engineers Need to Know Before Ordering the 1756-BA2

Community feedback from forums including PLCTalk, PLCS.net, MrPLC, Reddit r/PLC, and Rockwell Automation user communities reflects consistent praise for the 1756-BA2 as a reliable, predictable consumable. Technicians report that the OEM assembly performs as expected in panels maintained within reasonable thermal conditions, and the plug-and-play connector design means replacement is straightforward for any competent controls or maintenance technician. The part's broad availability through Rockwell-focused distributors is frequently cited as a practical advantage — when a battery low warning appears, most sites can source a replacement within a short timeframe rather than waiting on a special order.

Where community discussion turns critical is almost never about battery performance itself. The recurring friction points are cost sensitivity, ordering errors, and maintenance discipline. OEM pricing draws consistent comparison to generic lithium cells, and the debate over third-party equivalents is active in most forum threads on this topic. The expert consensus is nuanced: for critical systems or sites under OEM warranty requirements, the 1756-BA2 OEM assembly is the defensible choice. Where equivalents are considered, practitioners stress that the connector and lead configuration of any cross-reference must be confirmed physically — not assumed from a catalog description. Ignoring early battery low warnings is the most frequently flagged operational mistake, with multiple forum contributors reporting program loss incidents that were preceded by weeks of unacknowledged battery fault indicators.

The most damaging ordering mistake documented in community discussions is the 1756-BA1 versus 1756-BA2 confusion. Buyers who do not check the CPU nameplate and series before ordering — or who assume one ControlLogix battery part number covers the entire platform — account for the majority of wrong-part returns and delays. A second common mistake is forgetting to reconnect the battery plug after installation or commissioning, leaving the controller running with no active backup despite a physically present battery. The checklist below is drawn directly from these documented failure patterns and the Rockwell compatibility requirements for this part.

Battery Replacement and Installation Overview

The following is a high-level overview only. Always consult Rockwell Automation's official controller user manual for your specific 1756-L6x Series B CPU and follow all applicable site lock-out/tag-out and safety procedures before performing any battery maintenance.

  • Before starting, confirm that the replacement battery catalog number on the label reads 1756-BA2 and that the connector style matches your controller's battery port — do not install if there is any doubt.
  • Determine whether replacement will be performed with chassis power on or off, based on site safety procedures and Rockwell guidance; maintaining power during replacement is often recommended to protect program memory where permitted.
  • Disconnect the old 1756-BA2 assembly from the CPU battery port, remove the battery from its mounting location, and insulate the terminals of the used battery immediately to prevent short circuit.
  • Mount the new 1756-BA2 assembly and firmly seat the connector into the CPU battery port — confirm the connector is fully engaged, as a loose connection leaves the controller unprotected.
  • After restoration, verify via the controller's front-panel status indicators and engineering software that any battery low or battery fault indication has cleared, and log the replacement date in the plant maintenance record.

For storage and disposal: keep spare batteries in original packaging at around 25 °C and moderate humidity, record receipt and expected shelf-life dates in your spare parts system, and follow local regulations and company procedures for lithium battery recycling and disposal. The approximate short-term storage temperature range for the 1756-BA2 assembly is -45 °C to +85 °C, but long-term storage at elevated temperatures will reduce effective remaining life.

Wrong-Part Prevention: ControlLogix Battery Ordering Checklist

Before submitting a purchase request for the Allen-Bradley 1756-BA2, verify each of the following without exception:

  1. Confirm your CPU catalog number is a 1756-L6x Series B controller before specifying 1756-BA2.
  2. Verify the existing battery label and connector style in the panel matches "1756-BA2" before reordering.
  3. Do not substitute 1756-BA1 or other 1756-BAx variants without checking Rockwell documentation for your exact controller.
  4. Check plant or OEM standards: some sites require OEM batteries only and do not accept third-party equivalents.
  5. Confirm environmental conditions (control cabinet temperature and humidity) fall within the battery's specified limits.
  6. For Canadian sites, confirm local Rockwell distributor availability and import rules for lithium batteries.
  7. For large fleets, standardize on one battery type only if all controllers are within the supported 1756-L6x Series B range.
  8. Verify shelf-life and manufacturing date on stored spares before installation to avoid installing aged batteries.

If any item on this checklist raises a question you cannot resolve from your controller documentation, contact the LeadTime.ca team before ordering — we can validate compatibility against your CPU catalog number and series before the order is placed.

Frequently Asked Questions

My ControlLogix controller is showing a battery low warning — does this mean I need the 1756-BA2 specifically, or could it be a different battery?

Not necessarily the 1756-BA2. The correct battery depends entirely on your CPU catalog number and series. The 1756-BA2 is specified for 1756-L6x Series B controllers in the ControlLogix 5560 family. Check the nameplate on your CPU module and cross-reference against Rockwell documentation to confirm whether 1756-BA2, 1756-BA1, or another 1756-BAx variant is required. Installing the wrong assembly will not resolve the fault and may create a connector mismatch.

How often should a 1756-BA2 battery be replaced in a normal ControlLogix installation?

Rockwell Automation provides a minimum service life guideline based on operating temperature — the rated life applies when the battery is maintained within approximately 0 to 35 °C. Elevated cabinet temperatures shorten this interval meaningfully. Most maintenance teams use a combination of the manufacturer's guidance and plant-specific history to set replacement intervals, and many replace the battery proactively during scheduled shutdowns rather than waiting for a low-battery fault. Log replacement dates on the chassis and in your maintenance management system to manage the cycle accurately.

Can I use a third-party battery that cross-references to the 1756-BA2 to reduce spare parts cost?

Third-party assemblies marketed as 1756-BA2 equivalents exist, and some plants use them where OEM is not mandated by site or OEM standards. Before substituting, physically confirm that the connector type, lead length, and voltage match the OEM assembly — a catalog cross-reference alone does not guarantee mechanical interchangeability. For regulated industries, critical processes, or systems still under OEM warranty, the Allen-Bradley 1756-BA2 is the defensible choice that eliminates compatibility questions and preserves support standing.

Is it safe to replace the 1756-BA2 while the ControlLogix controller is powered and running?

Rockwell Automation's guidance on hot-swap battery replacement should be followed for your specific 1756-L6x Series B CPU — consult the controller user manual for your catalog number. Where site safety procedures permit and the manual supports it, performing replacement with control power maintained is often recommended specifically to protect program memory during the swap. Regardless of method, always ensure a current program backup exists in your engineering software before performing any battery maintenance.

How should spare 1756-BA2 batteries be stored, and how do I know if a spare is still serviceable?

Store spare assemblies in their original packaging at around 25 °C and moderate humidity, away from conductive materials. The short-term storage temperature range for the 1756-BA2 is approximately -45 °C to +85 °C, but long-term storage at the high end of that range will consume shelf life. Record the receipt date in your spare parts system and verify the manufacturing date on the battery label before installation — installing a battery near or past its recommended shelf life will result in premature low-battery faults and reduced program protection time.

What is the correct way to dispose of a used 1756-BA2 lithium battery?

The 1756-BA2 contains a lithium metal cell and must be handled as a lithium battery waste stream under local regulations. Insulate the connector and wire leads immediately after removal to prevent short circuits, and place the used battery in an appropriate, labeled container. Follow your site's environmental procedures and local lithium battery recycling or disposal regulations. Rockwell Automation provides a Safety Data Sheet for the 1756-BA2 — this document should be on file with your site safety team and referenced for disposal guidance.

Why Order the Allen-Bradley 1756-BA2 Through LeadTime.ca

  • LeadTime.ca specializes in industrial automation components including ControlLogix spares — orders ship worldwide, not only within a single region.
  • Specialist sourcing support means compatibility questions about CPU catalog numbers and series can be addressed before the order is placed, reducing wrong-part returns.
  • Current pricing and stock status are displayed live on the product page — no waiting for a quote on a standard consumable.
  • Volume pricing is available for fleet-wide battery replacements — contact the team directly for multi-unit orders.
  • Hard-to-find or short-lead-time parts are a core competency; if regional Rockwell distributor stock is depleted, LeadTime.ca can assist with sourcing alternatives.

At-a-Glance Summary

  • The Allen-Bradley 1756-BA2 is the OEM lithium metal battery assembly specified for ControlLogix 1756-L6x Series B CPUs in the ControlLogix 5560 family.
  • Nominal voltage is 3 V DC with a typical capacity of approximately 1200 mAh.
  • Battery assembly includes wire leads and a plug-in connector — it is not a generic coin cell.
  • Rated minimum service life applies when operating between approximately 0 and 35 °C; higher cabinet temperatures reduce this life.
  • Battery body dimensions are approximately 0.68 in x 1.38 in; assembly weight is approximately 36 g.
  • Short-term storage temperature range is approximately -45 °C to +85 °C; recommended long-term storage is around 25 °C in original packaging.
  • 1756-BA2 is not interchangeable with 1756-BA1 or other 1756-BAx variants without confirming controller catalog and series.
  • Widely stocked by Rockwell Automation distributors in North America; available for worldwide order through LeadTime.ca.
  • The most common ordering mistake is substituting 1756-BA1 for 1756-BA2 without checking the CPU nameplate — always verify catalog number and series first.
  • Lithium metal chemistry requires SDS compliance, proper storage, and regulated disposal handling.

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