CyberPower RB1290X2 teardown

Inside
2 x 12 V 9 Ah
Wiring
24 V series
List price
$117
Cell size
151 x 65 x 94 mm
Terminal
F2
Evidence on cell count
verified

What is inside the RB1290X2?

RB1290X2 holds two 12 V blocks wired in series rated 9 Ah, giving a 24 V bus. CyberPower publishes the cell count. Both blocks carry the same current and should be replaced together. Check the label on your old blocks before ordering a replacement.

FRONT ELEVATION: 2 x 12 V, 24 V DC BUSCELL 1tabs F2+−CELL 2tabs F2+−RED TO UPS (+)BLACK TO UPS (−)each cell 151 x 65 x 94 mmPLAN VIEW, TO SCALE: CASE FORMATS151 mm65Standard 7-9 Ah (this page)CSB HR1234WF2, 94 mm case height151 mm51Slim 6 AhCSB HR1224WF2F1, 94 mm case height90 mm705 Ah cubeCSB HR1221WF2, 102 mm case heightFASTON TAB WIDTH, ENLARGEDF1 4.75 mm / 0.187"F2 6.35 mm / 0.250"
Every ledger row for RB1290X2
FieldValueQuoteSource
cells2Battery Quantity | 2T1 cyberpowersystems.com
cell ah9Battery Size | 12 V / 9 AhT1 cyberpowersystems.com
envelope mm150 x 66 x 99(mm) | 150 x 66 x 99 (mm)T1 cyberpowersystems.com
msrp usd117MSRP | $117T1 cyberpowersystems.com
terminalF2Terminal: F2; Listing is for the Battery onlyT2 lowes.com

Which UPS models use the RB1290X2?

Of the 35 models we track, RB1290X2 fits CP1500PFCLCD, LX1500GU, CST1500SUC. 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 RB1290X2
UPSRatingSerial condition
CP1500PFCLCD1500 VA / 1000 WSerial starts CXX
LX1500GU1500 VA / 900 Wall serials
CST1500SUC1500 VA / 900 Wall serials

Which bare cells replace the RB1290X2?

Replace RB1290X2 with two 12V 9 Ah F2 cells and reuse the factory harness. CyberPower lists 150 x 66 x 99 mm. The terminal comes from a retailer cross-reference or inference, so check your old cell first. 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.
Check Prime Price & Stock on Amazon →
2 x CSB HR1234WF2 12V 9Ah High Rate (the high-rate option)
High-rate AGM, F2. Holds up best at UPS discharge rates.
Check Prime Price & Stock on Amazon →

Can LiFePO4 replace the RB1290X2?

A 12.8 V LiFePO4 pack fits the RB1290X2 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.

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 RB1290X2 cost against bare cells?

RB1290X2 lists at $117. Two bare cells cost about $69.88 at a non-Amazon single-unit reference price, a saving of roughly 40%. 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 RB1290X2 MSRP: $117. Typical Commodity Bare-Cell Band (Non-Amazon Reference): about $69.88 for 2 x CSB HR1234WF2. Reuse your factory wire harness to save about 40% against the OEM cartridge MSRP.