FANUC Battery Alarms: What CNC Operators Need to Know About the BR-2/3AGCT4A

A low-battery warning on a CNC machine may seem minor compared with a servo, spindle or control failure. But on FANUC equipment, backup batteries can play an important role in preserving information when the machine’s main power is switched off.

One replacement battery maintenance teams may encounter is the Panasonic BR-2/3AGCT4A, a 6V lithium battery pack associated with the FANUC reference A98L-0031-0025 for compatible applications.

Panasonic manufactures the battery cells, while FANUC manufactures the CNC and automation equipment in which this type of battery can be used. Understanding that distinction, and identifying the correct battery reference, is important when responding to a FANUC battery alarm.

What does a FANUC battery alarm mean?

FANUC systems use batteries for different purposes, so the first step when a battery warning appears is determining which battery the machine is referring to.

Maintenance teams may encounter terms such as FANUC SERVO BAT ALARM, ABS Servo Battery Alarm, BLAL or BLA when troubleshooting battery-related issues. These indications are associated with battery conditions in systems using absolute pulse coders or servo-related feedback.

FANUC documentation also identifies APC alarms in the 300–309 range. In particular, alarms 306, 307 and 308 relate to low or depleted APC battery voltage, while alarm 300 can indicate that a reference position return is required after absolute position information has been lost.

The distinction matters because not every FANUC alarm involving an encoder or servo system means that the battery itself has failed. For example, FANUC alarm 350 relates to a serial pulse coder fault, while alarm 351 indicates a serial pulse coder communication error. Battery-related diagnostic information can appear alongside these alarms, depending on the system and configuration.

For operators searching for terms such as “FANUC battery alarm,” “FANUC SERVO BAT ALARM” or “ABS Servo Battery Alarm,” identifying the exact alarm code and battery reference is therefore one of the most important first steps.

Why shouldn’t a low-battery warning be ignored?

A backup battery is a relatively small and inexpensive maintenance component compared with the equipment it helps support.

Depending on the FANUC system involved, loss of backup power can affect information required by the CNC or absolute position data. FANUC documentation for absolute Pulsecoders states that when the battery voltage reaches a low level, the battery should be replaced promptly. If the battery voltage falls far enough that absolute position data can no longer be held, additional reference-position procedures may be required.

This is why a BLAL or BLA battery low warning should not simply be cleared and ignored. The exact alarm terminology varies between FANUC controls and configurations, so maintenance teams should always refer to the documentation for the specific CNC and servo system.

For manufacturers operating multiple CNC machines, batteries can therefore be treated as preventive-maintenance components rather than parts that are considered only after an alarm appears.

Recording battery references and replacement dates, monitoring battery warnings and having the appropriate replacement available can help maintenance teams deal with the issue before it becomes more disruptive.

Understanding the Panasonic BR-2/3AGCT4A

The PANASONIC BR-2/3AGCT4A is a 6V lithium battery pack associated with FANUC reference A98L-0031-0025 for compatible industrial applications.

The pack is built using Panasonic BR-2/3AG lithium cells. According to Panasonic, each BR-2/3AG cell has a nominal voltage of 3V and a nominal capacity of 1,450 mAh. The manufacturer specifies an operating temperature range from -40°C to +85°C.

Panasonic also lists memory backup in large factory automation equipment among the applications for the BR-2/3AG and describes the cell as suitable for applications requiring long-term operating reliability.

These characteristics help explain why this type of industrial lithium battery is used in environments where backup power needs to remain dependable over extended periods.

The official Panasonic BR-2/3AG technical specifications provide further information on the cell’s electrical characteristics, dimensions and operating conditions.

BR-2/3AGCT4A and FANUC A98L-0031-0025: why the reference matters

Industrial maintenance teams often search using the machine manufacturer’s part number rather than the battery manufacturer’s reference.

In this case, someone searching for FANUC A98L-0031-0025 may ultimately need a Panasonic BR-2/3AGCT4A battery pack. Conversely, a technician who identifies a BR-2/3AGCT4A on an existing system may search directly for the Panasonic reference.

This is why checking both references can make sourcing a replacement easier.

For U.S. manufacturers looking for this specific battery, CNC-Shopping supplies the Panasonic BR-2/3AGCT4A / FANUC A98L-0031-0025 alongside a broader range of CNC and industrial automation components.

For maintenance teams, specialized industrial suppliers can be particularly useful when the challenge is not simply finding a battery, but identifying and sourcing the exact reference required by equipment that may have been operating for many years.

What do APC alarms 300–309 have to do with the battery?

The APC alarm range deserves particular attention when troubleshooting absolute position systems.

FANUC documentation identifies alarms 300 through 309 as part of the absolute pulse coder alarm group. The individual codes cover different conditions, including communication problems, pulse errors, battery voltage issues and reference-position requirements. Alarms 306, 307 and 308 are specifically associated with APC battery voltage, while alarm 309 concerns an unsuccessful reference-position return procedure.

This means that seeing an APC alarm does not automatically mean that a battery needs to be replaced. The specific code matters.

The same principle applies to alarms 350 and 351. These are associated with serial pulse coder faults and communication errors rather than being simple battery-low notifications. However, battery status can appear in the diagnostic information associated with pulse coder alarms, depending on the FANUC system.

For maintenance technicians, reading the complete alarm code and diagnostic information before replacing components can therefore prevent unnecessary parts replacement.

When should a FANUC CNC battery be replaced?

There is no single replacement procedure that should be applied to every FANUC CNC or servo system. The correct procedure depends on the equipment and on the function of the battery being replaced.

When a battery warning appears, maintenance teams should address it promptly rather than waiting for complete battery depletion.

Before replacing a CNC backup battery, technicians should confirm the correct part number and consult the applicable FANUC or machine-tool maintenance manual. The prescribed procedure should always be followed, particularly because the required machine power state during battery replacement can be important for preserving information.

FANUC America provides dedicated technical guidance for FANUC CNC battery replacement, reinforcing the role of battery replacement as a routine CNC maintenance task.

It is also important to remember that Panasonic BR-series batteries are primary lithium batteries and are not rechargeable.

From a FANUC battery alarm to preventive maintenance

A search for “FANUC battery alarm,” “FANUC SERVO BAT ALARM,” “ABS Servo Battery Alarm,” “BLAL,” “BLA,” “BR-2/3AGCT4A” or “A98L-0031-0025” often begins only after a warning has already appeared on a machine.

For maintenance teams, a more effective approach is to include backup batteries in routine CNC preventive maintenance.

Modern manufacturing facilities depend on increasingly sophisticated automation, but operational continuity does not always come down to major mechanical repairs or expensive electronic modules. Sometimes it depends on identifying and sourcing a relatively small component before it becomes a larger problem.

Knowing both the Panasonic and FANUC references, understanding the relevant APC alarm codes and maintaining a replacement history can help turn an unexpected CNC battery alarm into a planned maintenance task rather than an avoidable production disruption.