Asus C21N1421 Transformer Book T300chi Replacement Battery 7.6V 4900mAh
Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.
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Asus C21N1421 Transformer Book T300chi Replacement Battery 7.6V 4900mAh - 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 C21N1421 Transformer Book T300chi Replacement Battery 7.6V 4900mAh - is backordered and will ship as soon as it is back in stock.
Voltage
7.6V
Amp
4900mAh
Asus Transformer Book T300chi — 7.6V Li-Polymer Replacement Battery (C21N1421)
This 7.6V, 4900mAh (37.24Wh) Li-Polymer battery replaces the original cell in the Asus Transformer Book T300chi detachable tablet. It covers the T300CHI-FL121T, T300CHI-FL005T, T300CHI-FL073H, and over 37 additional T300CHI variants. Cross-references include C21N1421, 0B200-01520000, 0B200-00570200, and C21N1418.
- T300CHI tablet unit compatibility: All T300CHI variants share the same 7.6V battery rail, connector pinout, and BMS handshake protocol. The tablet component houses this cell independently from any keyboard dock — only the tablet half uses this battery.
- Bench tested on actual hardware: We ran the C21N1421 cell through a full charge and discharge cycle on T300CHI hardware. The BMS accepted the cell without fault codes, balanced both internal cells correctly, and reached cutoff voltage cleanly at both ends.
- Fuel gauge reset after installation: After fitting this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100% without using the device. This resets the fuel gauge IC calibration against the new cell and clears the inaccurate percentage readings that typically appear after a swap.
T300CHI shutting down at 15–25% remaining
The T300CHI combines a high-resolution display with active WiFi — both pull current simultaneously when in normal use. Under that combined load, voltage drops faster than the fuel gauge predicts, hitting the BMS low-voltage cutoff while the OS still reads 15–25%. This is a calibration gap, not a faulty cell. One full discharge-to-shutoff followed by an uninterrupted full charge resets the fuel gauge IC and aligns the percentage curve to the new cell's actual voltage profile.
Fast charging not available after battery swap
The T300CHI's charge IC runs a USB-PD negotiation handshake before enabling elevated charge rates. On a new cell, that negotiation sometimes fails on the first accepted cycle because the BMS has no charge history to reference. Plug in using the original Asus adapter and let the device complete one full uninterrupted charge from below 10% to 100%. After that cycle, the charge IC logs an accepted profile and fast charging becomes available on subsequent sessions.
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
My T300CHI shows 100% then drops to 60% within minutes — is the new battery faulty?
It's not a faulty cell. The fuel gauge IC was calibrated to your old battery's voltage curve and is misreading the new one. Run one complete discharge to automatic shutoff — don't manually power it off — then charge uninterrupted to 100% without using the tablet. That single cycle resets the calibration and the percentage display stabilises.
The T300CHI tablet feels warm near the top edge while charging after I swapped the battery — should I stop charging?
Warmth near the top edge is normal during the first few charge cycles on a new cell. The charge IC runs slightly higher current while it builds an accepted charge profile against the new battery. Surface temperature should stay below 40°C. If the tablet becomes hot to the touch or the charge stops before 100%, disconnect and check that the connector is fully seated — a partial connection causes the BMS to cycle on and off, which generates heat.
After replacing the battery, the T300CHI percentage drops faster from 100% than it did before — what's wrong?
The fuel gauge IC is drifting because it has no accurate baseline for the new cell's capacity. This shows up as a fast drop from 100% followed by a long hold at a lower percentage. Discharge the tablet completely to automatic shutoff, then charge it to 100% in one uninterrupted session with the screen off. The IC recalculates capacity against the actual cell and the drain rate normalises across the full charge range.
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