APC APCRBC124 teardown

Inside: 2 x 12 V 9 Ah
Wiring: 24 V series
List price: $181
Cell size: 151 x 65 x 94 mm
Terminal: F2
Evidence on cell count: verified

What is inside the APCRBC124?

APCRBC124 holds two 12 V blocks wired in series rated 9 Ah, giving a 24 V bus. APC titles it "Smart-UPS Line Interactive, 24V 9Ah". Both blocks carry the same current and should be replaced together. Check the label on your old blocks before ordering a replacement.

Every ledger row for APCRBC124
Field	Value	Quote	Source
oem title	APC Replacement Battery Cartridge for Smart-	APC Replacement Battery Cartridge for Smart-UPS Line Interactive, 24V 9Ah lead-acid battery	T1 se.com
msrp usd	181	MSRP$181.00	T1 shi.com
shi compat	for P/N: BR1500G-RS, BX1500M, BX1500M-LM60,	for P/N: BR1500G-RS, BX1500M, BX1500M-LM60, SMC1000-2UC	T1 shi.com
bus v	24	Voltage \| 24V	T2 partssource.com
cells	2	The APCRBC124 cartridge contains two 12V batteries wired in series to produce 24V total	T2 batterymart.com
terminal	F2	[2 Pack] 12 Volt 9 Ah Sealed Lead Acid Rechargeable Battery - F2 Terminal	T2 batterymart.com

Which UPS models use the APCRBC124?

Of the 35 models we track, APCRBC124 fits BX1500M, BR1500G. That list comes from the manufacturer's pages, and they sometimes disagree with reseller listings. Where a model splits by serial number, its UPS page shows which prefix takes this cartridge, so check your label before you order.

Models on this site that use APCRBC124
UPS	Rating	Serial condition
BX1500M	1500 VA / 900 W	all serials
BR1500G	1500 VA / 865 W	all serials

Which bare cells replace the APCRBC124?

Replace APCRBC124 with two 12V 9 Ah F2 cells and reuse the factory harness. The 12V 9 Ah F2 format sold for this cartridge is 151 x 65 mm. A reseller confirms the terminal type, so no guesswork is needed. Keep the old harness, because bare cells ship without leads.

2 x Mighty Max ML9-12 12V 9Ah F2

Standard AGM, F2. The like-for-like choice.

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2 x CSB HR1234WF2 12V 9Ah High Rate (the high-rate option)

High-rate AGM, F2. Holds up best at UPS discharge rates.

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Can LiFePO4 replace the APCRBC124?

A 12.8 V LiFePO4 pack fits the APCRBC124 bay, but its BMS sets the limit. A 12 A BMS allows about 236 W on this 24 V bus. Series packs add volts rather than amps, and they can drift apart on the charger. Measure your real load before you buy.

High-voltage and thermal safety

UPS battery bays carry high-current DC, up to about 60 A at full load on these models and more at cutoff. Inverter capacitors inside the case can stay charged after unplugging, so never open a unit beyond its battery door. A shorted or mismatched pack can overheat or start a fire. The manufacturers sell only sealed lead-acid replacement packs (APCRBC, RB, RBC) for these units, and we found no OEM approval for LiFePO4. BMS trip limits, series balance drift and 0 V lockout on 24 V drop-ins are modeled from published BMS current ratings, not from UL or OEM certification, and no qualified engineer has reviewed them. Figures are estimates, so check your own unit's label and manual.

2 x 12.8V 10Ah LiFePO4, F1 terminal

Listing claims a 20 A BMS and doesn't say whether that is continuous.

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2 x F1 to F2 terminal adapters, pair (4 adapters needed)

One pair covers one cell.

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At the listing's 20 A claim the ceiling is 394 W, and at 12 A it is 236 W. Why that matters.

How much does the APCRBC124 cost against bare cells?

APCRBC124 lists at $181. Two bare cells cost about $69.88 at a non-Amazon single-unit reference price, a saving of roughly 61%. The reference is a CSB block at one store, and it is not an Amazon price. Reusing the harness is what makes this work.

Official APCRBC124 MSRP: $181. Typical Commodity Bare-Cell Band (Non-Amazon Reference): about $69.88 for 2 x CSB HR1234WF2. Reuse your factory wire harness to save about 61% against the OEM cartridge MSRP.