Telstra Galaxy S III GT-i9300T Replacement Battery 3.8V 2100mAh
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Telstra Galaxy S III GT-i9300T Replacement Battery 3.8V 2100mAh - 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.
Telstra Galaxy S III GT-i9300T Replacement Battery 3.8V 2100mAh - is backordered and will ship as soon as it is back in stock.
Voltage
3.8V
Amp
2100mAh
Telstra Galaxy S III GT-i9300T — 3.8V Li-ion Replacement Battery
This is a 3.8V, 2100mAh Li-ion replacement battery for the Samsung Galaxy S III GT-i9300T smartphone. It fits the standard battery bay without modification and connects directly to the phone's charge IC and fuel gauge circuit. Capacity is sourced from the product specification — 7.98Wh total energy.
- GT-i9300T, Galaxy S III, Galaxy S3 fit: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 63.20 × 50.40 × 5.40mm cell slots flush against the contact rail, and the three-pin connection supplies voltage, ground, and the NTC thermistor line the charge IC needs to regulate current.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a GT-i9300T unit. The BMS accepted the charge current without tripping, the thermistor line reported correctly, and the fuel gauge IC registered a completed charge cycle by the end of the first run.
- Fuel gauge recalibration on first install: Disable fast charging and run one complete discharge-to-charge cycle after fitting this cell. The fuel gauge IC on the GT-i9300T is calibrated to the discharge curve of the old cell. One full cycle lets the coulomb counter reset its reference points against the new cell before high-current charging begins.
Sudden shutdown at 20–30% on the GT-i9300T after a cell swap
This is a voltage cliff issue, not a capacity fault. Under modem radio or screen load, the new cell's voltage drops faster than the fuel gauge expects at that state of charge. The phone's power IC sees voltage fall below the cutoff threshold and shuts down before the percentage reaches zero. Run one full discharge cycle — draw the battery down to automatic shutdown from 100% — and the coulomb counter recalibrates its curve against actual cell behaviour.
GT-i9300T not powering on after the replacement battery sat in storage
Li-ion cells in storage self-discharge over time. If the voltage drops below approximately 2.5V per cell, the BMS enters lockout mode and the phone will not respond to a normal power-on press. Connect the phone to a wall charger — not a PC USB port — and leave it for 15–20 minutes without attempting to power it on. The charge IC on the GT-i9300T will trickle current into the cell to recover voltage above the BMS re-enable threshold, after which normal charging resumes. If the charge indicator never appears after 30 minutes on wall power, check that the battery connector is fully seated against the three contact pins.
Compatible Models
Technical Specifications
Product Highlights
- Brand: Telstra
- Manufacturer: CS
- Series: X-Longer
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The GT-i9300T shows 100% on the new battery but drops to 15% within an hour of light use — is the cell faulty?
The cell is not faulty. The fuel gauge IC on the GT-i9300T is still running the discharge model it built against the old, degraded cell. It has no accurate reference point for the new cell's voltage curve, so percentage readings jump erratically until recalibration happens. Run one complete cycle — charge to 100% uninterrupted, then use the phone until it shuts itself off automatically — and the coulomb counter will rebuild its curve against the new cell. After that cycle, percentage reporting stabilises.
Fast charging stopped working after I fitted the new battery in my GT-i9300T — the phone just trickle charges now.
On the first cycle after a cell swap, the GT-i9300T's charge IC sometimes withholds high-current charging because the BMS on the new cell has not yet completed a handshake with the phone's charge controller. The phone defaults to trickle charge as a safety measure. Let the phone complete one full charge from near-empty to 100% on standard charge — not fast charge — using a wall adapter. After that cycle completes, the charge IC recognises the new BMS and fast charging re-enables on the next session.
My GT-i9300T gets noticeably warm near the battery compartment while charging the new cell — is that normal?
Some warmth on the first few charge cycles is expected. A new cell has slightly higher internal impedance than a broken-in one, which means the charge IC dissipates a small amount of extra energy as heat while pushing current into it. This should reduce noticeably after two or three full charge cycles as the cell's impedance settles. If the phone becomes hot to the touch — not just warm — or the charge indicator disappears mid-cycle, remove the battery and check that the NTC thermistor pin on the connector is making clean contact with the phone's battery bay terminal.
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