APC SUA1500RM2U battery teardown
- Bare cells needed
- 4 x 12 V 9 Ah
- Max DC draw
- 49.8 A
- OEM cartridge
- RBC24
- Cell size
- 151 x 65 x 94 mm
- In inches
- 5.94 x 2.56 x 3.70 in
- Terminal
- F2 check yours
- Rating
- 1500 VA / 980 W
- Topology
- Line Interactive
- Waveform
- Not verified
- Transfer time
- Not verified
- OEM list price
- $789
- DC bus
- 24 V (assumed)
- Last verified
- 2026-11-02
- LiFePO4 at full load
- RED
What battery does the SUA1500RM2U actually use?
The SUA1500RM2U uses RBC24, which holds four 12 V blocks, assumed to be two parallel pairs, rated 9 Ah on a 24 V DC bus. Each block fits a 151 x 65 mm bay with F2 terminals. This model has no serial-number split that we could find.
| Spec | Value | Source |
|---|---|---|
| VA and watts | 1500 VA / 980 W | T2 servertechsupply.com |
| Topology | Line Interactive | T2 manuals.plus |
| Waveform, in the OEM's words | Not verified | T1 se.com |
| Transfer time | Not verified | T1 se.com |
| OEM cartridge | RBC24 | T1 se.com |
| Why Does APC Assign a Different Cartridge SKU? | APC doesn't publish a reason. RBC24 lists at $789, against APCRBC124 on the BX1500M at $181, and APCRBC124 on the BR1500G at $181, and APCRBC161 on the BN1500M2 at $164. All are 4 x 12 V blocks on a 24 V bus, so the difference we can document is SKU, sled and price, not the cells. | |
| OEM list price | $789 | T1 shi.com |
Battery Mart lists 13.50 x 8.50 x 3.26 in for the tray, and four 151 x 65 mm cells lie flat in that space, two by two. Schneider calls this "12V 9AH". Battery Mart lists 24 V 14 Ah and another seller says 7.5 Ah cells. We use the OEM capacity, and 24 V with four cells means two parallel pairs. APC marks the cartridge non-stock. Full RBC24 teardown
How many DC amps does the SUA1500RM2U pull?
At its full 980 W rating, the SUA1500RM2U pulls about 49.8 A from its 24 V bus, and about 56.9 A as the battery sags to 21 V cutoff. Those figures assume 82% inverter efficiency, because APC doesn't publish one for battery mode.
| AC load | Nominal | At cutoff |
|---|---|---|
| 25 W | 1.3 A | 1.5 A |
| 60 W | 3.0 A | 3.5 A |
| 100 W | 5.1 A | 5.8 A |
| 200 W | 10.2 A | 11.6 A |
| 300 W | 15.2 A | 17.4 A |
| 490 W | 24.9 A | 28.5 A |
| 980 W | 49.8 A | 56.9 A |
Is LiFePO4 safe in the SUA1500RM2U?
A 12 A BMS limits the SUA1500RM2U to about 472 W, well below its 980 W rating. At full load the verdict is RED. We could not verify a LiFePO4 pack that fits this bay and harness, so we link none. APC doesn't support this swap. Drag the slider below to test your own load.
GREY: load is fine, but no verified cell fits
- DC draw now
- 12.7 A
- At 21 V cutoff
- 14.5 A
- Safe AC load
- 472 W
SUA1500RM2U: lead-acid anchored to OEM half and full-load runtimes, LiFePO4 on a flat energy curve with inverter tare, at 82% inverter efficiency. A real inrush can trip a BMS below this ceiling. RBC24 teardown.
| BMS continuous | Safe AC load | Share of 980 W |
|---|---|---|
| 10 A | 197 W | 20% |
| 12 A | 236 W | 24% |
| 15 A | 295 W | 30% |
| 20 A | 394 W | 40% |
Four independent BMS boards in one pack multiply the balance risk. So we show no drop-in link.
How long will the SUA1500RM2U run on each battery?
APC publishes about 26.5 min at 490 W and 7.4 min at 980 W on the stock cells, and our curve passes through both points. The 12V 9 Ah high-rate AGM option adds runtime in the same case. Drag the slider for your own load.
| AC load | Stock 9 Ah | 12V 9 Ah high-rate AGM | LiFePO4 10 Ah |
|---|---|---|---|
| 25 W | 14.2 hr | 14.2 hr | no verified pack |
| 60 W | 5.3 hr | 5.7 hr | no verified pack |
| 100 W | 2.9 hr | 3.2 hr | no verified pack |
| 200 W | 76 min | 88 min | no verified pack |
| 300 W | 47 min | 56 min | no verified pack |
| 490 W | 27 min | 32 min | no verified pack |
| 980 W | 7.4 min | 9.4 min | no verified pack |
| Load | APC published | Raw Peukert | This site | Source |
|---|---|---|---|---|
| 490 W | 26.5 min | 24 min | 26.5 min | T2 excessups.ca |
| 980 W | 7.4 min | 11 min | 7.4 min | T2 excessups.ca |
Upgraded AGM scales from the anchored curve, with k = 1.18 standard and 1.12 high-rate. LiFePO4 uses a flat energy curve with inverter tare. Method.
Which replacement should you buy for the SUA1500RM2U?
There are three routes for the SUA1500RM2U. Path A swaps in four bare cells and reuses your harness. Path B is withheld, because no verified pack fits. Path C replaces the whole UPS, which makes most sense for units over six years old.
| Path | Best for | Load limit | Main risk |
|---|---|---|---|
| A: bare SLA swap | Lowest cost, any load | 980 W | Terminal or case mismatch |
| B: drop-in LiFePO4 | Light loads, long life | not offered | BMS trip, charger mismatch |
| C: native LiFePO4 UPS | A unit over 6 years old, or high loads | 1000 W | Slower transfer than this UPS |
Path A: the bare-cell SLA swap
Surge-safe, because AGM has no BMS to trip.
Path B: drop-in LiFePO4
Path C: a native LiFePO4 UPS
Worth it if this UPS is 6 or more years old, if a fault above isn't a battery problem, or if you need more than the BMS limit. Listings and reviews put Goldenmate's transfer at 8 to 20 ms, so check that your PC tolerates it.
How do you move the SUA1500RM2U harness to bare cells?
You move the factory jumper and leads from the old blocks to the new ones, in the same polarity. Unplug the UPS first, and tape each lead as it comes off, because the battery stays live. Sealed sleds must be opened first. No soldering is needed.
- Shut down the load, turn the UPS off and unplug it from the wall.
- Take a photo of the wiring. Open the battery door or sled and slide the pack out.
- Pull the red clip off the positive tab, and tape it straight away.
- Remove the black lead and tape it. Then lift off the jumper between the cells, with any fuse your harness has.
- Check the new cells have the right size and tabs, then add any adapters from the parts list.
- Fit the jumper first, from the positive of one cell to the negative of the next. Fit the leads one at a time, matching your photo, and remove the tape only from the lead you are fitting.
- Measure about 25 to 27 V across the two outer leads before you close the pack. Slide it back, plug in and charge for the time the manual gives before relying on it.
- Recycle the old cells at a battery retailer. Never bin lead-acid.
Sixty seconds is the best case for a loose-cell unit. Sealed sleds need opening first, and opening them may affect your warranty and APC's equipment guarantee.
How much do you save over the RBC24?
RBC24 lists at $789, and four bare cells cost about $139.76 at a non-Amazon single-unit price, saving roughly 82%. That reference is a premium CSB block from one store, so cheaper brands may save more. Check Amazon for its current price.
| Item | Price | Source |
|---|---|---|
| Official RBC24 MSRP | $789 | T1 shi.com |
| Typical Commodity Bare-Cell Band (Non-Amazon Reference): 4 x CSB HR1234WF2 | $139.76 | T2 batterystore.com |
| Saving when you reuse the harness | $649.24 (82%) | computed |
What do the SUA1500RM2U alarms and fault codes mean?
We don't have an alarm table for the SUA1500RM2U, because the sources we captured don't include one. Rather than guess at what a beep means, check the manual that came with your unit before you buy a replacement battery or contact support.
We could not get this model's alarm table, so we list nothing rather than guess. Check the manual that came with your unit.
| SUA1500RM2U | Not captured |
|---|
How do you reach the battery in the SUA1500RM2U?
We have no verified door procedure for the SUA1500RM2U. APC sells a replacement cartridge for it, but we did not capture the steps. Follow the manual for your unit, and don't open the case to find out how it comes apart. Contact the manufacturer if you are unsure.
| Field | Value | Source |
|---|---|---|
| Battery door access | No procedure captured. Treat as a service item | none |
| Cell orientation | Not stated in the manual we captured | none |
| Harness connector type | Not stated in the manual we captured | none |
| Cell layout | 4 x 12 V, assumed two parallel pairs | verified |