CNC Backup Drive Fanuc Battery Replacement A98L-0031-0026

A98L-0031-0026 | FANUC 3V Lithium Battery — Black Modular Type / 0.055 lbs / CNC SRAM Backup / A02B-0309-K102

"Black Modular Type" — The Hard Case Cartridge Format

FANUC's designation "Black Modular Type" identifies the A98L-0031-0026 as a self-contained battery cartridge — not a wire-lead cell pack, but a rigid black plastic housing that integrates the lithium cell, internal electronics, and 3-pin connector into a single modular unit.

This modular format serves the battery's installation context inside a FANUC CNC controller:

Snap-in installation: The black cartridge slides into the controller's dedicated battery compartment and locks in place — held by the compartment's retention mechanism rather than a cable connector hanging freely.

3-pin fixed connector: The moulded 3-pin connector on the cartridge end mates with the CNC's battery socket with defined polarity — the connector cannot be reversed or incorrectly inserted.

Self-contained: All battery components — lithium cell, protective circuitry, and connector interface — are enclosed in the black modular housing. No exposed components, no loose wire leads.

Key Specifications

What A98L-0031-0026 Protects in the FANUC CNC

FANUC CNC systems using A98L-0031-0026 store critical operational data in battery-backed SRAM:

Part programmes: All NC programmes stored in CNC memory — tool paths, cutting conditions, and machining sequences for every job on the machine.

CNC parameters: The machine-specific configuration data set during machine tool commissioning — axis stroke limits, servo tuning, display settings, and all system parameters.

Tool offset tables: Measured tool length and diameter compensation data for all tools in the magazine — re-measurement required if lost.

PMC ladder programme: The machine tool builder's integrated PLC programme embedded in the CNC — governs spindle interlocks, coolant, door safety, and all machine-specific functions.

Weight as a Quality Indicator

The specified net weight of 0.055 lbs (approximately 25g) provides a practical verification point. The cartridge weight reflects:

• The lithium cell's mass (approximately 45–60g full assembly)
• The plastic cartridge housing
• The 3-pin connector and any internal protection components

A significantly lighter battery suggests internal components differ from the OEM specification. A battery meeting the 0.055 lbs specification has the correct cell mass and internal construction.

FAQ

Q1: What is the difference between A98L-0031-0026 and A98L-0031-0028?

Both are FANUC 3V black modular lithium batteries for CNC SRAM backup, but they serve different CNC models and use different connector configurations. A98L-0031-0026 (A02B-0309-K102) is for FS0i-MD/MF and related Series 0i family CNCs. A98L-0031-0028 (A02B-0323-K102) is for another CNC variant. Always confirm from the CNC's alarm message or battery compartment label which A98L specification applies to the specific machine.

Q2: Can A98L-0031-0026 be replaced while the FANUC CNC is powered on?

Yes — with the CNC powered and in standby or run mode, the internal supply maintains SRAM. The black cartridge can be removed and the replacement inserted without data loss. Swap quickly. Never leave the CNC without a battery while the power supply is off and the SRAM must be retained.

Q3: How does A98L-0031-0026 compare to earlier FANUC battery formats like CR17450SE-R?

CR17450SE-R (A98L-0031-0012) is a single cylindrical cell with pressure contact terminals used in older FANUC Series 15/16/18 CNC controllers — a discrete cell in a cell holder. A98L-0031-0026 is a modular cartridge for the newer FS0i series — an integrated unit combining cell, housing, and 3-pin connector. The modular format simplifies replacement and ensures correct installation compared to the older discrete cell format.

Q4: What alarm code does the FANUC FS0i CNC generate when A98L-0031-0026 needs replacement?

The FANUC FS0i and related CNC systems generate alarm 9F (or SW0100 "Battery voltage low") when the A98L-0031-0026 voltage drops below the detection threshold — typically displayed as an alarm with axis identifiers at power-up. Replace at this alarm. After replacement, the alarm should clear on the next power cycle.