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PartsTable / BATTERY / 81Y4579
81Y4579 ✓ Verified by PartsTable
IBM · BATTERY · SUPERCAP
WHAT YOU NEED TO KNOW
Supercapacitors have long duration but they wear out. We recommend buying new when possible, though refurbished can work. Always check the date code. Key checks: Recommend NEW.
Long duration but wear out
PRODUCT OVERVIEW
IBM BATTERY CAPACITOR PACK 13.5V 6.4F

The IBM 81Y4579 is a Flash-Backed Write Cache capacitor pack, designed for enterprise RAID controllers in enterprise servers. It provides backup power to the FBWC module during unexpected power loss, ensuring cached write data is safely committed to flash memory. Unlike traditional batteries, the supercapacitor design offers a longer operational lifespan with no scheduled replacement cycles and no temperature-related degradation.

This is a high-volume replacement part in TPM market as enterprise servers remain widely deployed.

WHERE IT FITS
BATTERY→ SUPERCAP→ 81Y4579
SPECIFICATIONS
Drive Bays1x 3.5" LFF
COMPONENT DIAGRAM
CAP 72V + - CAP 72V BRACKET TO CTRL CABLE: — ~76 mm CACHE BACKUP | Supercapacitor | Cable: — Connects to RAID controller | | Controller: See controller spec SCHEMATIC: + - 2S2P SUPERCAP PACK TITLE CACHE BATT PN 81Y4579 MFR IBM IBM Battery Capacitor Pack 13.5V 6.4f
KEY FEATURES
•
Flash-Backed Write Cache Capacitor
•
Supercapacitor Technology
Longer lifespan than traditional batteries — no scheduled replacement cycles
•
Hot-Plug Capable
•
No Maintenance Required
TYPICAL APPLICATIONS
  • RAID cache protection during power loss events
  • Write-back cache enablement for storage controllers
  • Enterprise server data integrity assurance
  • Hot-swap battery/capacitor replacement in production
VERIFIED SUBSTITUTES & CROSS-REFERENCES 2
00JY023Compatible
IBM Cache Battery Capacitor for RAID for M5100/M5200 Series - FRU
compatible
47C8696Compatible
IBM Cache Battery Capacitor for RAID for M5200 Series - FRU
compatible
LIFECYCLE
StatusUNKNOWN
Availability—
RoHS CompliantEAR99ESD SensitiveDG Class 9 — LithiumRestricted Air Freight
THIS PART SUBSTITUTES FOR 2
00JY023SUBSTITUTE
IBM Cache Battery Capacitor for RAID for M5100 Series - FRU
IBM
47C8696SUBSTITUTE
IBM Cache Battery Capacitor for RAID for M5100 Series - FRU
IBM
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FREQUENTLY ASKED QUESTIONS
What is 81Y4579?
81Y4579 is a IBM Battery Capacitor Pack 13.5V 6.4f manufactured by IBM. It is classified as a BATTERY (SUPERCAP).
What parts can replace 81Y4579?
There are 2 known substitutes for 81Y4579: 00JY023, 47C8696. Substitute compatibility should be verified for your specific system.
Is 81Y4579 still available?
81Y4579 is currently Unknown.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026