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Sealed black rectangular battery with two terminals

BatteryJack inc.

BatteryJack inc. HC1221W CSB UPS Replacement Battery APC RBC21 BF500 500U 400C

SKU CH-5NXB-X7JMQ

Sealed AGM replacement battery fits APC RBC21, BF500, 500U and 400C UPS units

  • Advanced AGM technology ensures spill‑proof operation in any position
  • Expected 4‑7 year service life reduces replacement frequency
  • 100 % OEM compatible with APC RBC21 BF500 500U 400C
  • Maintenance‑free design eliminates water checks and specific‑gravity tests
  • Over 90 % gas recombination keeps internal pressure stable

Direct APC RBC21 replacement

This sealed AGM battery fits APC UPS models BF500, 500U and 400C. It is built for users who need a drop-in power source without modifying cables or brackets. The maintenance-free design suits home offices, small servers and network closets where uptime matters.

100 % OEM-compatible fit

The unit matches the original RBC21 form factor and terminal layout exactly. No adapters or wiring changes are required during installation. Buyers who need a different voltage, capacity or connector type should look elsewhere.

4–7 year expected service life

The AGM chemistry delivers reliable backup for typical loads such as a router, modem and single workstation. Runtime shortens as the battery ages or when heavier equipment is connected. Users running multiple servers or high-draw appliances will exhaust capacity faster.

Highlights

  • Advanced AGM technology ensures spill‑proof operation in any position
  • Expected 4‑7 year service life reduces replacement frequency
  • 100 % OEM compatible with APC RBC21 BF500 500U 400C
  • Maintenance‑free design eliminates water checks and specific‑gravity tests
  • Over 90 % gas recombination keeps internal pressure stable

Specifications

No published specifications for this item yet.

Questions about this item

How long can the 4-7 year expected life actually last inside a running UPS?

The 4-7 year expected life applies when the battery is kept on continuous float charge at moderate temperature; deeper or more frequent discharges will shorten the practical service span.

What does the 90% gas recombination rate mean for everyday UPS operation?

Over 90% of gas generated during normal charge and discharge cycles recombines inside the sealed case, so the battery stays maintenance-free and does not vent electrolyte.

Will the HC1221W fit the existing battery tray in my APC BF500 unit?

The HC1221W is built as a 100% OEM replacement for APC RBC21 packs used in BF500, 500U and 400C models, matching the original dimensions and terminal layout.

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