Asus VivoBook 15 X505B B31N1631 Replacement Battery 11.52V
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Asus VivoBook 15 X505B B31N1631 Replacement Battery 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.
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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 15 X505B B31N1631 Replacement Battery 11.52V - is backordered and will ship as soon as it is back in stock.
Voltage
11.52V
Amp
3500mAh
Asus VivoBook 15 X505B Series — 11.52V Li-Polymer Replacement Battery (B31N1631)
This is an 11.52V, 3500mAh (40.32Wh) lithium-polymer battery for the Asus VivoBook 15 X505B, X505Z, F505Z, X505BA, and over 200 related VivoBook 15 variants. It replaces part number B31N1631 and its cross-references (0B200-02510200E, 0B200-02510500, 0B200-02510000). Fit it when the original cell no longer holds charge or fails to power the laptop through basic daily tasks.
- VivoBook 15 X505 and F505 platform fit: These models share a common 3-cell Li-Polymer architecture running an 11.52V nominal rail. The connector pinout and BMS handshake protocol are identical across the X505B, X505Z, F505Z, and X505BA lines, which is why one part number covers all of them.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the X505 platform. The BMS communicated correctly with the EC, charge current tapered as expected at high state-of-charge, and no fault codes triggered during the test sequence.
- Post-install calibration on the X505 platform: After fitting this cell, run the laptop down to hibernate-cutoff under normal use, then charge uninterrupted to 100%. This forces the VivoBook's fuel gauge IC to recalibrate against the new cell's actual capacity and clears the inaccurate battery health warning that appears in BIOS after every cell swap.
BIOS reporting poor battery health immediately after fitting the new cell
The VivoBook 15 BIOS reads health data from EEPROM registers that were written by the old cell during its lifetime. When a new cell goes in, those registers still hold the degraded values from the previous pack. The EC flags this as a fault before the new cell has completed a single cycle. Run one full discharge-to-hibernate followed by an uninterrupted charge to 100% — this triggers the battery learn cycle and rewrites the relevant registers with data from the new cell.
Laptop shuts down at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage curve. Under combined CPU and display load, the cell voltage drops faster than the uncalibrated gauge expects, and the EC triggers an emergency shutdown before the displayed percentage reaches zero. It is a software-side miscalibration, not a fault with the cell itself. Complete two full discharge-to-hibernate and full-charge cycles — after that the gauge tracks the real voltage curve and shutdowns at low-but-not-zero readings 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
The VivoBook shows the wrong Wh rating in system info after I put the new battery in — is the cell actually the right capacity?
The Wh figure shown in Windows Device Manager and battery diagnostics tools is pulled from the EEPROM on the cell, not measured live. A new cell's EEPROM may report a slightly different value than what was printed on the old pack, and the fuel gauge IC hasn't yet mapped actual capacity from real cycles. The rated capacity for this cell is 40.32Wh at 11.52V. Run two full discharge-to-hibernate and charge-to-100% cycles — once the fuel gauge IC has calibrated, the reported figure aligns with the cell's actual chemistry.
My VivoBook 15 charge stops at 80% and won't go higher — is this a faulty cell?
That behaviour is almost always the BIOS charge limit feature, not a cell fault. Asus VivoBook firmware includes a battery health charging mode that caps charge at 80% to reduce long-term cell stress — it ships enabled on some units and can be toggled on accidentally. Open MyAsus or Asus Battery Health Charging from the system tray, set the mode to Full Capacity, then unplug and replug the charger to force the EC to re-read the new charge ceiling.
The fuel gauge is jumping all over the place — showing 60%, then 45%, then 70% within a few minutes of use
The fuel gauge IC on the VivoBook 15 EC uses a stored voltage-to-capacity map built from the old cell's discharge curve. A new Li-Polymer cell has a slightly different curve, so the gauge mis-reads state-of-charge until it collects real data from full cycles. The erratic jumps settle after two complete discharge-to-hibernate and uninterrupted full-charge cycles. If the gauge is still unstable after three full cycles, check that the battery connector is fully seated — a loose connection causes voltage noise that the IC reads as capacity swings.
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