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656809-B21 — Network Technical Data

HP · TRANSCEIVER · POWER_CABLE
WHAT YOU NEED TO KNOW
Very common replacement part Capacitors degrade slower than batteries but still lose capacity over time
CABLE LENGTH IS CRITICAL: 660093-001 = 36" (2U+), 654873-003 = 24" (1U)
PRODUCT OVERVIEW
HP BATTERY CAPACITOR PACK WITH 36 INCH CABLE

The HP 656809-B21 is a Flash-Backed Write Cache capacitor pack with a 36-inch cable, designed for HPE Smart Array controllers in ProLiant Gen8 and Gen9 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 the long-cable variant (36") suitable for 2U and larger chassis configurations where the controller and capacitor mounting points are farther apart. The short-cable variant is 654873-003 (24"). This is a high-volume replacement part in TPM market as ProLiant Gen8 and Gen9 servers remain widely deployed.

WHERE IT FITS
TRANSCEIVER→ POWER_CABLE→ 656809-B21
SPECIFICATIONS
Part Number656809-B21
ManufacturerHP
FITS THESE MACHINES
HPE StoreOnce 5650 System
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 656809-B21 MFR HP HP Battery Capacitor Pack with 36 Inch C
KEY FEATURES
•
Flash-Backed Write Cache Capacitor
•
36" Cable Length
Reaches controller slot in 2U+ chassis
•
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
SUBSTITUTES & CROSS-REFERENCES 2
654873003SubstituteBROKER-VERIFIED
HP Battery Capacitor Pack with 36 Inch Cable
substitute
660093001SubstituteBROKER-VERIFIED
HP Battery Capacitor Pack with 36 Inch Cable
substitute
LIFECYCLE

No lifecycle data available.

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FREQUENTLY ASKED QUESTIONS
What is 656809-B21?
656809-B21 is a HP Battery Capacitor Pack with 36 Inch Cable manufactured by HP. It is classified as a TRANSCEIVER (POWER_CABLE).
What parts can replace 656809-B21?
There are 2 known substitutes for 656809-B21: 654873003, 660093001. Substitute compatibility should be verified for your specific system.
Is 656809-B21 still available?
656809-B21 is currently Unknown.
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PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.