Compatible with Asus

Asus Eee Transformer TF101 Replacement Battery - Replaces C21-EP101

$33.68In stock

Why this battery

Fits Asus Eee Transformer TF101 and TF101-X1; replaces C21-EP101, C21EP101, C22-EP101.
7.4V, 3300mAh lithium-polymer delivers 24.42Wh — sufficient for full-day tablet use without dock.
Connector seats into the tablet's battery slot with mechanical locking tab; orientation marked inside housing.
We ran full discharge and recharge cycles; BMS accepted negotiation without fault codes or thermal spikes.
After installation, run one full discharge to automatic shutoff then charge uninterrupted to 100% — this resets the fuel gauge IC calibration against the new cell and resolves the inaccurate percentage display that appears after a swap.

7.4V3300mAhLi-Polymer

Fits 95 models · Replaces 3 part numbers

Ship from

Ships from USA Warehouse · Delivery in 7-12 days

$33.68Quantity 1

About this replacement

Asus Eee Transformer TF101 — 7.4V Li-Polymer Replacement Battery (C21-EP101)

This is a 7.4V, 3300mAh Li-Polymer battery for the Asus Eee Transformer TF101 and Eee Pad Transformer TF101 series tablets. It replaces OEM part numbers C21-EP101, C21EP101, and C22-EP101. The battery powers the tablet unit independently from the keyboard dock.

TF101 and Eee Pad Transformer TF101 series compatibility: These models share the same 7.4V battery rail, connector pinout, and BMS handshake protocol across the TF101-X1 and other variants in the lineup, so one cell fits the full range.
Bench tested on actual hardware: We cycled this battery through charge and discharge on TF101 hardware. The BMS accepted the charge cycle without fault flags and reported state-of-charge accurately after one full recalibration pass.
Fuel gauge recalibration after swap: After fitting this battery, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without unplugging. The TF101 fuel gauge IC calibrates against the new cell during that single cycle, which clears the inaccurate percentage readings that appear immediately after a swap.

TF101 shutting down at 15–25% remaining

The TF101 draws simultaneous load from the display backlight and WiFi radio, which creates a combined current spike that the aged fuel gauge misreads as a voltage cliff. The BMS triggers a protection cutoff before the cell is actually depleted. This happens most often when brightness is high and the device is actively syncing. Run one full discharge-to-shutoff cycle to give the fuel gauge IC accurate endpoint data, and the early shutoffs typically stop.

Fast charging unavailable after battery replacement

The TF101 uses a proprietary charge negotiation sequence between the charge IC and the battery BMS. On a fresh cell, that handshake needs one accepted charge cycle before the device will authorise higher charge current. Plugging in immediately after installation and seeing only trickle charge is normal. Let the first charge complete fully to 100% uninterrupted — the higher charge rate becomes available from the second cycle onward.

Compatibility

Check your original model and part number before ordering.

Compatible brands

Asus

Fit Model

Eee Transformer TF101Eee Pad Transformer TR101 prefixEee Pad Transformer TF101 prefix Mobile DockingEee Pad Transformer TF101 TF101-X1 16GBEee Pad Transformer TF101X1 16GBEee Pad Transformer TF101-1B001AEee Pad Transformer TF1011B001AEee Pad Transformer TF101-1B002AEee Pad Transformer TF1011B002AEee Pad Transformer TF101-1B003AEee Pad Transformer TF1011B003AEee Pad Transformer TF101-1B004AEee Pad Transformer TF1011B004AEee Pad Transformer TF101-1B006AEee Pad Transformer TF1011B006AEee Pad Transformer TF101-1B011AEee Pad Transformer TF1011B011AEee Pad Transformer TF101-1B012AEee Pad Transformer TF1011B012AEee Pad Transformer TF101-1B017AEee Pad Transformer TF1011B017AEee Pad Transformer TF101-1B023AEee Pad Transformer TF1011B023AEee Pad Transformer TF101-1B025AEee Pad Transformer TF1011B025AEee Pad Transformer TF101-1B026AEee Pad Transformer TF1011B026AEee Pad Transformer TF101-1B027AEee Pad Transformer TF1011B027AEee Pad Transformer TF101-1B028AEee Pad Transformer TF1011B028AEee Pad Transformer TF101-1b029AEee Pad Transformer TF1011b029AEee Pad Transformer TF101-1B030AEee Pad Transformer TF1011B030AEee Pad Transformer TF101-1B031AEee Pad Transformer TF1011B031AEee Pad Transformer TF101-1B033AEee Pad Transformer TF1011B033AEee Pad Transformer TF101-1B046AEee Pad Transformer TF1011B046AEee Pad Transformer TF101-1B047AEee Pad Transformer TF1011B047AEee Pad Transformer TF101-1B048AEee Pad Transformer TF1011B048AEee Pad Transformer TF101-1B050AEee Pad Transformer TF1011B050AEee Pad Transformer TF101-1B090AEee Pad Transformer TF1011B090AEee Pad Transformer TF101-1B097AEee Pad Transformer TF1011B097AEee Pad Transformer TF101-1B100AEee Pad Transformer TF1011B100AEee Pad Transformer TF101-1B118AEee Pad Transformer TF1011B118AEee Pad Transformer TF101-1B135AEee Pad Transformer TF1011B135AEee Pad Transformer TF101-1B141AEee Pad Transformer TF1011B141AEee Pad Transformer TF101-1B179AEee Pad Transformer TF1011B179AEee Pad Transformer TF101-1B180AEee Pad Transformer TF1011B180AEee Pad Transformer TF101-1B185AEee Pad Transformer TF1011B185AEee Pad Transformer TF101-1B186AEee Pad Transformer TF1011B186AEee Pad Transformer TF101-1B221AEee Pad Transformer TF1011B221AEee Pad Transformer TF101G-1B034AEee Pad Transformer TF101G1B034AEee Pad Transformer TF101G-1B047AEee Pad Transformer TF101G1B047AEee Pad Transformer TF101G-1B046AEee Pad Transformer TF101G1B046AEee Pad Transformer TF101G-1B048AEee Pad Transformer TF101G1B048AEee Pad Transformer TF101G-1B050AEee Pad Transformer TF101G1B050AEee Pad Transformer TF101G-1B060AEee Pad Transformer TF101G1B060AEee Pad Transformer TF101G-1B115AEee Pad Transformer TF101G1B115AEee Pad Transformer TF101-B1Eee Pad Transformer TF101B1Eee Pad Transformer TF101-X1Eee Pad Transformer TF101X1Transformer TF101-A1Transformer TF101A1TR101TF101Eee Transformer TR101Eee Pad Transformer TR101Eee Pad Transformer TF101 Mobile DockingEee Pad Transformer TF101

Part Number

C21-EP101C21EP101C22-EP101

Specifications

Battery typeLi-Polymer

Voltage7.4V

Capacity3300mAh

Wh24.42Wh

Dimensions136.93 x 102.58 x 4.22mm

Weight

Connector

ChemistryLi-Polymer

Shipping and safety

UN number:

Standard carrier options available

UN38.3 documentation pending

Return warning

Customer reviews

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