Asus C21N1347 X555 Laptop Replacement Battery 7.6V 4800mAh
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Asus C21N1347 X555 Laptop Replacement Battery 7.6V 4800mAh - 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 C21N1347 X555 Laptop Replacement Battery 7.6V 4800mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.6V
Amp
4800mAh
Asus X555 Series — 7.6V Li-Polymer Replacement Battery (C21N1347)
This is a 7.6V, 4800mAh (36.48Wh) lithium-polymer cell that replaces the original C21N1347 battery in the Asus X555 laptop series. It fits the X555, X555LA, X555LD, X555LN, and over 296 additional X555 variants. Install it when the original cell no longer holds charge or the system shuts down unexpectedly on battery power.
- X555 series fit: Every X555 variant in this line shares the same 7.6V two-cell Li-Polymer architecture, the same connector pinout, and the same BMS handshake protocol. That is why one part number covers the full range from X555LA through to X555LN and beyond.
- Bench tested on actual hardware: We ran this cell on an X555LA and cycled it through charge and discharge under full CPU and display load. The BMS reported correct voltage at each state-of-charge threshold and did not trip on load transitions.
- First-cycle calibration on X555: After fitting, run the laptop on battery until it hibernates on its own, then charge uninterrupted to 100% without using the machine. This gives the fuel gauge IC a full-range sweep against the new cell and resets the learn cycle the BIOS uses to calculate remaining capacity.
BIOS reporting poor battery health immediately after fitting a new cell
The Asus BIOS reads health data cached from the old battery's EEPROM and flags the new cell as degraded before it has completed a single cycle. This is not a fault with the replacement — it is stale data from the previous cell persisting in firmware. 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 charge curve and the warning clears.
Laptop shuts off at 20–30% charge shown on the X555
This happens when the cell voltage drops below the BMS cutoff threshold before the fuel gauge reaches zero — a calibration gap, not a defective cell. The fuel gauge IC built into the X555 board maps percentage to voltage curves learned from the previous battery. On a fresh cell those curves do not match yet. Complete two full discharge-to-hibernate and full-charge cycles back-to-back. After the second cycle the gauge recalibrates and the shutdown point shifts back toward 0%.
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 Windows show the Asus X555 battery Wh rating as different from what the new cell is rated at?
The Wh figure Windows displays is pulled from the EEPROM data embedded in the battery pack, which stores the manufacturer's rated capacity. A replacement cell may use a slightly different chemistry profile that maps to a different Wh figure at the same nominal voltage, so the number in Windows and the label on the pack can diverge. This is a data difference, not a capacity fault. Run two full calibration cycles and the OS fuel gauge will settle against the actual cell behaviour.
The fuel gauge on my X555 jumps around wildly — shows 60%, then 45%, then 70% within minutes of unplugging.
The fuel gauge IC on the X555 motherboard tracks charge state by learning the voltage curve of the installed cell over several cycles. A brand-new cell has a different internal resistance profile from the worn cell it replaced, so the IC's model is wrong until it re-learns. The jumping will reduce noticeably after the first full discharge-to-hibernate cycle and should stabilise by the end of the second. Do not interrupt either charge cycle — let it run to 100% without use.
My X555 stops charging at 80% and never goes higher — is the replacement cell faulty?
Almost certainly not. Asus ships several X555 BIOS versions with a charge-limit feature enabled by default — it caps charging at 80% to reduce long-term cell wear when the laptop is plugged in most of the time. Open the Asus Battery Health Charging utility (pre-installed on most X555 builds) or check BIOS under Advanced → Power Management for a charge ceiling setting. Set it to full capacity mode and the charge limit lifts immediately.
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