Asus FX504 B31N1726 Replacement Battery 11.4V 4200mAh
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Asus FX504 B31N1726 Replacement Battery 11.4V 4200mAh - 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.
Disclaimer
Disclaimer
⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.
🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Asus FX504 B31N1726 Replacement Battery 11.4V 4200mAh - is backordered and will ship as soon as it is back in stock.
Voltage
11.4V
Amp
4200mAh
Asus FX504 Series — 11.4V Li-Polymer Replacement Battery (B31N1726)
This is an 11.4V, 4200mAh (47.88Wh) Li-Polymer battery for the Asus TUF Gaming FX504 series laptop. It fits FX504, FX504G, FX504GE, and related variants using OEM part B31N1726. Install it when the original cell no longer holds a charge or the laptop won't run unplugged.
- FX504 series compatibility: These models share the same 11.4V three-cell Li-Polymer configuration, connector pinout, and BMS communication protocol. The FX504G and FX504GE use the same battery bay and charge controller, so one cell covers the full lineup without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an FX504GE unit. The BMS handshake completed on first boot, charge current stepped down correctly at 80% and 95%, and the protection circuit tripped cleanly at the low-voltage threshold without hard shutdown.
- Post-install calibration on the FX504: After fitting, run the laptop down to hibernate cutoff on battery alone — no AC during discharge. Then charge uninterrupted to 100% without waking the machine. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the FX504 shuts down at 20–30% remaining after a battery swap
The FX504's fuel gauge IC builds a discharge curve against the original cell's EEPROM data. A new cell has different internal resistance, so the IC's voltage-to-capacity map is wrong from the start. Under full CPU and display load, the cell voltage drops faster than the old curve predicts, and the system reads it as critically low — triggering shutdown well above actual depletion. Run two full discharge-to-hibernate cycles followed by uninterrupted full charges. The fuel gauge IC recalibrates against the new cell's actual curve and the early shutdowns stop.
BIOS reporting battery health as poor or capacity as 0% after replacement
The FX504 BIOS reads health data from the cell's EEPROM — the old cell's wear data does not clear when you swap the battery. On first boot with a new cell, the BIOS compares the fresh cell's voltage signature against stored degradation records and flags a mismatch as poor health. This is a BIOS learn cycle fault, not a faulty cell. Boot into Windows, open MyASUS or the ASUS Battery Health Charging utility, and let the system complete one full charge cycle — the BIOS rewrites its battery reference data and the health warning clears.
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 Asus FX504 shows the new battery as 0% or "unknown" in Windows — is the cell dead?
No — the fuel gauge IC is reading stale EEPROM data from the old cell and hasn't mapped the new one yet. Windows reports what the IC feeds it, not the actual cell state. Plug in the AC adapter and let the battery charge uninterrupted to 100% without waking the machine. After one full charge cycle the IC rewrites its reference data and the percentage reads correctly.
My FX504 replacement battery shows 47Wh in Windows but system info still lists the old capacity — is the Wh rating wrong?
The Wh figure in system info pulls from the EEPROM on the old cell if the BIOS hasn't completed a learn cycle yet. The actual cell fitted is rated at 47.88Wh — the hardware spec is correct. Run one full discharge-to-hibernate on battery only, then charge uninterrupted to 100%. The BIOS overwrites the cached Wh value with data from the new cell on the next boot.
Charge stops at 80% on the FX504 and won't go higher — is the replacement cell faulty?
This is almost always the ASUS Battery Health Charging feature in MyASUS, not a cell fault. The firmware locks charge to 80% in "Balanced" mode to reduce cell stress during long AC-connected use. Open MyASUS, go to Battery Health Charging, and switch from Balanced to Full Capacity mode. Charge should resume past 80% immediately.
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