Eaton 5S1500LCD battery teardown
- Bare cells needed
- 2 x 12 V 9 Ah
- Max DC draw
- 45.7 A
- OEM cartridge
- No SKU in our sources
- Cell size
- 151 x 65 x 94 mm
- In inches
- 5.94 x 2.56 x 3.70 in
- Terminal
- F2
- Rating
- 1500 VA / 900 W
- Topology
- Line Interactive
- Waveform
- Not verified
- Transfer time
- Under 5 ms
- OEM list price
- not published
- DC bus
- 24 V
- Last verified
- 2026-11-01
- LiFePO4 at full load
- RED
What battery does the 5S1500LCD actually use?
The 5S1500LCD uses Eaton 5S cell pair, which holds two 12 V blocks in series 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 / 900 W | T1 cdn.blueally.com |
| Topology | Line Interactive | T1 eaton.com |
| Waveform, in the OEM's words | Not verified | T1 cdn.blueally.com |
| Transfer time | Under 5 ms | T1 eaton.com |
OSI lists 5.94 x 2.55 x 3.87 in with .250 faston tabs, two per unit.
How many DC amps does the 5S1500LCD pull?
At its full 900 W rating, the 5S1500LCD pulls about 45.7 A from its 24 V bus, and about 52.3 A as the battery sags to 21 V cutoff. Those figures assume 82% inverter efficiency, because Eaton 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 |
| 450 W | 22.9 A | 26.1 A |
| 900 W | 45.7 A | 52.3 A |
Is LiFePO4 safe in the 5S1500LCD?
A 12 A BMS limits the 5S1500LCD to about 236 W, well below its 900 W rating. At full load the verdict is RED. Packs in series can drift apart on the charger, so balance them first. 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
5S1500LCD: 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.
| BMS continuous | Safe AC load | Share of 900 W |
|---|---|---|
| 10 A | 197 W | 22% |
| 12 A | 236 W | 26% |
| 15 A | 295 W | 33% |
| 20 A | 394 W | 44% |
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 5S1500LCD run on each battery?
Eaton publishes about 13 min at 420 W and 2 min at 900 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 | 6.0 hr | 6.4 hr | 4.3 hr |
| 60 W | 2.2 hr | 2.4 hr | 2.4 hr |
| 100 W | 71 min | 82 min | 1.6 hr |
| 200 W | 31 min | 38 min | 53 min |
| 300 W | 19 min | 24 min | 0 min, BMS trip |
| 450 W | 11 min | 14 min | 0 min, BMS trip |
| 900 W | 2.0 min | 2.6 min | 0 min, BMS trip |
| Load | Eaton published | Raw Peukert | This site | Source |
|---|---|---|---|---|
| 420 W | 13 min | 13 min | 13 min | T1 cdn.blueally.com |
| 900 W | 2 min | 5.1 min | 2 min | T1 cdn.blueally.com |
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 5S1500LCD?
There are three routes for the 5S1500LCD. 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 | 900 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 | 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
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 Under 5 ms, so check that your PC tolerates it.
How do you move the 5S1500LCD 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 Eaton's equipment guarantee.
How much do you save over the Eaton 5S cell pair?
We can't state a saving for Eaton 5S cell pair, because we found no published list price for it. Any figure here would be a guess, so this page leaves it out rather than estimating one for you. Compare the list price with your own quote.
| Item | Status |
|---|---|
| Eaton 5S cell pair list price | not published |
| Verified bare-cell reference | none |
What do the 5S1500LCD alarms and fault codes mean?
We don't have an alarm table for the 5S1500LCD, 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.
| 5S1500LCD | Not captured |
|---|
How do you reach the battery in the 5S1500LCD?
We have no verified door procedure for the 5S1500LCD. The manufacturer says this battery should be replaced by qualified personnel. Treat the unit as a service item, 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 | 2 x 12 V, in series | verified |