SRF StarXtrem 2 Replacement Battery 3.8V 3400mAh Li-Polymer
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SRF StarXtrem 2 Replacement Battery 3.8V 3400mAh Li-Polymer - 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.
SRF StarXtrem 2 Replacement Battery 3.8V 3400mAh Li-Polymer - is backordered and will ship as soon as it is back in stock.
Voltage
3.8V
Amp
3400mAh
SRF StarXtrem 2 — 3.8V Li-Polymer 3400mAh Replacement Battery
This is a 3.8V Li-Polymer cell rated at 3400mAh (12.92Wh) for the SRF StarXtrem 2 and StarXtrem II smartphones. It replaces the original cell when the phone fails to hold charge, shuts down unexpectedly, or shows erratic battery percentage readings. Physical dimensions are 95.35 × 57.17 × 4.19mm — verify against your existing cell before installing.
- StarXtrem 2 and StarXtrem II compatibility: Both model names reference the same hardware platform. The battery connector pinout, BMS handshake voltage, and physical footprint are identical across both variants — one cell fits both.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the StarXtrem 2 platform. The BMS accepted the charge curve without rejection, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
- Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. The fuel gauge IC in the StarXtrem 2 calibrates itself against the new cell's discharge curve — skipping this step causes the percentage counter to read incorrectly against the fresh cell's actual capacity profile.
Sudden shutdown at 20–30% on the StarXtrem 2 after cell replacement
The StarXtrem 2 fuel gauge IC stores a learned discharge curve from the old cell. When a new cell is installed, the IC maps percentage readings against that old curve. A new Li-Polymer cell has a steeper voltage drop in the lower charge band, so the phone's modem and screen load pull the cell voltage below the BMS cutoff threshold before the OS registers critical battery level. The result is a hard shutdown that appears at 20–30% on the status bar. One full slow-charge cycle forces the coulomb counter to resync against the new cell's actual voltage floor.
USB charging stops being accepted immediately after fitting the new cell
On the first connection after a cell swap, the charge IC on the StarXtrem 2 may not negotiate the charge protocol correctly with the new BMS — the handshake between the USB port controller and the replacement cell's protection circuit can time out on the first attempt. Disconnect the cable, power the phone off completely, then reconnect to a standard 5V charger rather than a fast-charge adapter. Once the first charge cycle completes at standard current, the BMS registers as initialised and fast charging resumes normally on subsequent connections.
Compatible Models
Technical Specifications
Product Highlights
- Brand: SRF
- Manufacturer: CS
- Series: X-Longer
- Color: Black
- Product Type: Li-Polymer
- Battery Type: Li-Polymer
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
My StarXtrem 2 powers off by itself when the screen shows around 25% battery — is the new cell faulty?
This is a fuel gauge calibration issue, not a faulty cell. The phone's coulomb counter was mapped to the old cell's discharge curve, and the new Li-Polymer cell hits its BMS voltage cutoff before the OS reaches the low-battery warning. Run one full slow-charge cycle — charge from flat to 100% with fast charging disabled — and the fuel gauge IC will resync to the new cell's actual discharge curve. After that cycle, the shutdowns stop.
The battery percentage on my StarXtrem 2 jumps around erratically after I fitted the replacement — goes from 60% to 45% in seconds.
The fuel gauge IC is recalibrating against the new cell and has no reliable reference data yet. It is reading voltage and estimating percentage from a curve that no longer matches the installed cell. One complete discharge-to-charge cycle at standard current gives the IC enough data points to build an accurate model. Percentage readings stabilise after that first full cycle completes.
The StarXtrem 2 feels warm near the battery during the first charge after replacing the cell — is that normal?
A new Li-Polymer cell has higher internal impedance than a used one, and the charge IC pushes current into that resistance, generating more heat in the first few cycles. This is expected behaviour during initial charging and reduces as the cell breaks in over two or three full cycles. Keep the phone out of a case during that first charge to allow heat to dissipate. If the back becomes uncomfortably hot to hold — above roughly 45°C — disconnect the charger and let it cool before continuing.
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