APC BN1100M2 battery teardown
Also Sold As / Retail Channel Equivalent: BN1100M2-CA Same OEM manual or cartridge listing.
- Bare cells needed
- 2 x 12 V 7 Ah
- Max DC draw
- 30.5 A
- OEM cartridge
- APCRBC160
- Cell size
- 151 x 65 x 94 mm
- In inches
- 5.94 x 2.56 x 3.70 in
- Terminal
- F2 check yours
- Rating
- 1100 VA / 600 W
- Topology
- Line Interactive
- Waveform
- Simulated / Stepped
- Transfer time
- 8ms typical : 10 ms maximum
- OEM list price
- $156
- DC bus
- 24 V
- Last verified
- 2026-11-01
- LiFePO4 at full load
- RED
What battery does the BN1100M2 actually use?
The BN1100M2 uses APCRBC160, which holds two 12 V blocks in series rated 7 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 | 1100 VA / 600 W | T1 se.com |
| Topology | Line Interactive | T1 se.com |
| Waveform, in the OEM's words | Stepped approximation to a sinewave | T1 se.com |
| Transfer time | 8ms typical : 10 ms maximum | T1 se.com |
| OEM cartridge | APCRBC160 | T1 se.com |
| OEM list price | $156 | T1 shi.com |
Battery Mart lists this as two 12V cells in series, 289 x 64 x 95 mm overall, which is the standard 151 x 65 mm format end to end. Schneider titles this "12V 7.2Ah" and its manual table says 12 Vdc, but its BR1000MS page lists 24 V and 7.0 Ah, and Battery Mart says two cells in series. We model 24 V. Full APCRBC160 teardown
How many DC amps does the BN1100M2 pull?
At its full 600 W rating, the BN1100M2 pulls about 30.5 A from its 24 V bus, and about 34.8 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 |
| 600 W | 30.5 A | 34.8 A |
Is LiFePO4 safe in the BN1100M2?
A 12 A BMS limits the BN1100M2 to about 236 W, well below its 600 W rating. At full load the verdict is RED. Packs in series can drift apart on the charger, so balance them first. APC doesn't support this swap. Drag the slider below to test your own load.
RED: BMS trip hazard
- DC draw now
- 12.7 A
- At 21 V cutoff
- 14.5 A
- Safe AC load
- 236 W
BN1100M2: 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. APCRBC160 teardown.
| BMS continuous | Safe AC load | Share of 600 W |
|---|---|---|
| 10 A | 197 W | 33% |
| 12 A | 236 W | 39% |
| 15 A | 295 W | 49% |
| 20 A | 394 W | 66% |
Balance every pack first. Two independent BMS boards on one series charger can drift apart, and one can cut off early. Series drift and 0 V lockout explained.
How long will the BN1100M2 run on each battery?
APC publishes about 13.8 min at 300 W and 4.3 min at 600 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 7 Ah | 12V 9 Ah high-rate AGM | LiFePO4 10 Ah |
|---|---|---|---|
| 25 W | 4.3 hr | 6.2 hr | 4.3 hr |
| 60 W | 1.5 hr | 2.3 hr | 2.4 hr |
| 100 W | 50 min | 78 min | 1.6 hr |
| 200 W | 22 min | 36 min | 52 min |
| 300 W | 14 min | 23 min | 0 min, BMS trip |
| 600 W | 4.3 min | 7.4 min | 0 min, BMS trip |
| Load | APC published | Raw Peukert | This site | Source |
|---|---|---|---|---|
| 300 W | 13.8 min | 14 min | 13.8 min | T1 se.com |
| 600 W | 4.3 min | 6.2 min | 4.3 min | T1 se.com |
Same footprint, 28.6% more rated capacity. 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 BN1100M2?
There are three routes for the BN1100M2. Path A swaps in two bare cells and reuses your harness. Path B adds LiFePO4 for loads under 394 W, by the listing's 20 A claim. 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 | 600 W | Terminal or case mismatch |
| B: drop-in LiFePO4 | Light loads, long life | 394 W on the listed 20 A | BMS trip, charger mismatch |
| C: native LiFePO4 UPS | A unit over 6 years old, or high loads | 800 W | Slower transfer than this UPS |
Path A: the bare-cell SLA swap
Surge-safe, because AGM has no BMS to trip. 7 Ah and 9 Ah cells share the 151 x 65 x 94 mm case, so 9 Ah adds 28.6% rated capacity.
Path B: drop-in LiFePO4
Safe to about 394 W if the listing's 20 A BMS is continuous, or 236 W at 12 A. Check your load before you click.
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, against this unit's 8ms typical : 10 ms maximum, so check that your PC tolerates it.
How do you move the BN1100M2 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 its fuse if your harness has one.
- 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 other. 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 APCRBC160?
APCRBC160 lists at $156, and two bare cells cost about $69.88 at a non-Amazon single-unit price, saving roughly 55%. 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 APCRBC160 MSRP | $156 | T1 shi.com |
| Typical Commodity Bare-Cell Band (Non-Amazon Reference): 2 x CSB HR1234WF2 | $69.88 | T2 batterystore.com |
| Saving when you reuse the harness | $86.12 (55%) | computed |
What do the BN1100M2 alarms and fault codes mean?
APC Back-UPS Pro BN user guide lists 13 signals we track for the BN1100M2. Only 2 of them point to the battery, and 7 mean you should not buy batteries yet. Read your signal below first, because a new battery won't fix a charger, a relay or an overload.
| Signal | Meaning | What to do | Battery swap? | Source |
|---|---|---|---|---|
| 4 beeps every 30 seconds | Running on battery. Usually a power cut, not a dead battery | Save your work. This alone is no reason to replace the battery. | Not a fault | T1 manual |
| Continuous beeping | Low battery, very little runtime left | Save work and shut down. Recharge once power returns. | Not a fault | T1 manual |
| Continuous tone | The battery backup outlets are overloaded | Unplug something. A new battery won't help. | Do not buy batteries | T1 manual |
| Chirps every 2 seconds | Battery disconnected | Reseat the battery connector before you order anything. | Check first, then decide | T1 manual |
| Continuous chirping | The battery failed the automatic test | Replace the battery. Mute pauses the chirping. | Path A swap fixes this | T1 manual |
| Flashing Replace Battery icon, empty capacity icon | End of battery life | Replace the battery as early as you can. | Path A swap fixes this | T1 manual |
| F01 | On-battery overload | Turn it off, unplug non-essential equipment, turn it back on. | Do not buy batteries | T1 manual |
| F02 | On-battery output short | Turn it off, unplug everything, turn it on, then reconnect one item at a time. If it trips with nothing connected, contact support before buying cells. | Check first, then decide | T1 manual |
| F04 | Clamp short | The manual says you can't correct this yourself. Contact support, and if the unit is out of warranty compare Path C. | Do not buy batteries | T1 manual |
| F05 | Charge error | The manual says you can't correct this yourself. Contact support, and if the unit is out of warranty compare Path C. | Do not buy batteries | T1 manual |
| F06 | Relay welding | The manual says you can't correct this yourself. Contact support, and if the unit is out of warranty compare Path C. | Do not buy batteries | T1 manual |
| F07 | Temperature | The manual says you can't correct this yourself. Contact support, and if the unit is out of warranty compare Path C. | Do not buy batteries | T1 manual |
| F09 | Internal error | The manual says you can't correct this yourself. Contact support, and if the unit is out of warranty compare Path C. | Do not buy batteries | T1 manual |
How do you reach the battery in the BN1100M2?
On the BN1100M2, the manual says: toolless: press the locking tabs and pull the door away. Inside there are two batteries of about 151 x 65 mm. Check the details below before you start, turn the unit off and unplug it first, and photograph the wiring so you can match it later.
| Field | Value | Source |
|---|---|---|
| Battery door access | Toolless: press the locking tabs and pull the door away | T1 manual |
| Cell orientation | Lay the UPS with the battery door facing up | same manual |
| Harness connector type | Not stated in the manual we captured | same manual |
| Cell layout | 2 x 12 V, in series | verified |