Asus VivoBook S15 S531FA Compatible Battery B31N1842 11.52V
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Asus VivoBook S15 S531FA Compatible Battery B31N1842 11.52V - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
Battery Care Tips
🔹 Getting Started
Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.
🔹 Keep It Healthy
Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.
Delivery and Shipping
Delivery and Shipping
🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.
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Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Asus VivoBook S15 S531FA Compatible Battery B31N1842 11.52V - is backordered and will ship as soon as it is back in stock.
Voltage
11.52V
Amp
3550mAh
Asus VivoBook S15 S531FA / S531FL — 11.52V Li-Polymer Replacement Battery (B31N1842)
This is an 11.52V, 3550mAh (40.9Wh) Li-Polymer replacement battery for the Asus VivoBook S15 series. It fits the S531FA-EJ003T, S531FA-EJ188T, S531FL-EJ154T, S530FA-EJ269, and over 100 additional VivoBook S15 variants that share the B31N1842 or 0B200-03440000 part number. Voltage, connector pinout, and physical dimensions — 224 × 144 × 6.46mm — match the original cell specification.
- VivoBook S15 S531 and S530 compatibility: These models share the same 3-cell 11.52V architecture, connector, and BMS handshake protocol. The B31N1842 part number spans both the FA and FL sub-variants because Asus used a single battery platform across that chassis generation.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a VivoBook S15 chassis. The BMS accepted the cell without fault codes, charge current stepped down correctly at the CV phase, and the BIOS read the battery as present and charging from first power-on.
- Post-install calibration on the VivoBook S15: After fitting, run one full discharge until the laptop hibernates on its own, then charge uninterrupted to 100% without using the laptop. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting poor battery health immediately after fitting a new cell
The VivoBook S15 BIOS reads health data from the battery's EEPROM, which stores cycle count, rated capacity, and state-of-health flags written by the previous cell. A brand-new cell arrives with its own EEPROM baseline, and the BIOS flags a mismatch until it completes a learn cycle. This is not a fault with the replacement cell. Run one full discharge-to-hibernate followed by an uninterrupted charge to 100% — after that cycle, the BIOS recalculates health against the new cell's actual data and the warning clears.
Laptop shuts down at 20–30% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under full load — CPU boost plus display backlight together pull more current than the fuel gauge IC accounted for. The percentage shown is based on a calibration curve that hasn't yet been mapped to the new cell, so the displayed figure is ahead of the real state of charge. The fix is two full calibration cycles: discharge to hibernate cutoff, then charge to 100% each time. After two cycles the fuel gauge IC maps the voltage curve accurately and the early shutdowns stop.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Asus
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-Polymer
- Battery Type: Li-Polymer
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
Why does MyAsus show the new battery as "0% health" or "unknown" right after I installed it?
The VivoBook S15 BIOS reads health status from EEPROM data stored on the battery cell itself — the old cell's EEPROM recorded its own degraded history, and the new cell's EEPROM hasn't been read through a full learn cycle yet. The BIOS flags this mismatch as poor or unknown health until it can calibrate. Run one full discharge to hibernate and then charge uninterrupted to 100%. After that single learn cycle, the BIOS re-reads the EEPROM correctly and the health display updates.
The battery percentage in Windows is jumping around wildly — drops from 60% to 10% in minutes then climbs back up. What's wrong?
The fuel gauge IC in the VivoBook S15 uses a stored calibration curve to convert cell voltage into a percentage — that curve was built around the old cell's chemistry signature. With a new cell installed, the IC is reading voltage against the wrong map, so the percentage output is erratic. This is not a cell fault. Do two full discharge-to-hibernate cycles followed by uninterrupted charges to 100%. After the second cycle the fuel gauge IC has enough data to remap its curve to the new cell and the readout stabilises.
System Info shows my new battery as 40Wh but Windows Reports a different Wh rating — which is correct?
The Wh figure Windows pulls from Device Manager comes from the EEPROM's "design capacity" field, which was written by the original cell manufacturer and may not exactly match the replacement cell's rated chemistry. The physical cell in this battery is rated at 40.9Wh at 11.52V and 3550mAh — that is the authoritative spec. The EEPROM figure updates after one full charge-discharge learn cycle; once the BIOS completes calibration, the reported value aligns to the actual cell data.
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