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Rectangular black sealed lead-acid battery with recessed terminals measuring 5.51 by 1.89 by 4.0 inches

BatteryJack inc.

BatteryJack inc. RBC21 12V 5Ah Sealed Lead Acid UPS Replacement Battery

SKU CH-22EJ-K0YHG

12 V 5 Ah sealed lead-acid battery replaces APC RBC21 and compatible Belkin, CyberPower and CSB models using AGM technology

  • Advanced AGM technology delivers reliable sealed power
  • Expected battery life of 4-7 years supports long-term UPS operation
  • 100 percent OEM compatible replacement fits APC RBC10 and RBC21 models
  • Maintenance free design requires no fluid checks or upkeep
  • Compact 5.51 by 1.89 by 4.0 inch form factor fits tight UPS compartments

Purpose & Fit

This 12V 5Ah sealed lead acid battery replaces the RBC21 pack in compatible APC Back-UPS Office and Belkin Pro UPS units. It suits administrators who need a direct swap to restore runtime on supported models. Buyers whose UPS requires a different voltage, capacity or connector layout cannot use this pack.

Thermals, Noise & Power

The AGM construction is sealed and maintenance free, so the unit produces no audible noise and requires no fluid checks during its service life. Normal float charging in the host UPS draws only the trickle current the charger supplies, adding negligible heat to the cabinet. Expected service life spans four to seven years under typical standby conditions.

Deciding Specification

The critical match is the 12V 5Ah rating combined with the recessed terminal layout measuring 5.51 by 1.89 by 4.0 inches. Only UPS models listed in the compatibility table that share this exact voltage, capacity and physical footprint will accept the pack.

How it compares

Measured against everything we stock in UPS Replacement Batteries, at today’s prices. Recalculated every night.

Price $18.99
Cheaper than about 75% of the 3,915 comparable items (median $39.99).

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Specifications

No published specifications for this item yet.

Questions about this item

How do I install the RBC21 battery in my APC Back-UPS unit and which step is often missed?

Remove the front cover, disconnect the old battery leads, slide the new 5.51" x 1.89" x 4.0" unit into the recessed compartment, then reconnect the leads — many forget to re-seat the cover latch securely.

What maintenance or replacement will the RBC21 need during its service life?

The sealed AGM design is maintenance-free; plan to replace the battery after 4 to 7 years when runtime drops below your UPS load requirements.

What limit appears first when the RBC21 runs a continuous load near the UPS’s 325 VA rating?

The 5 Ah capacity at 12 V will be depleted in a short time, causing the UPS to shut down once the voltage falls below the inverter cutoff threshold.

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