Sony Xperia ST27 Replacement Battery AGPB009-A003 3.7V 1250mAh
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Sony Xperia ST27 Replacement Battery AGPB009-A003 3.7V 1250mAh - 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.
Sony Xperia ST27 Replacement Battery AGPB009-A003 3.7V 1250mAh - is backordered and will ship as soon as it is back in stock.
Voltage
3.7V
Amp
1250mAh
Sony Xperia ST27 / ST27i — 3.7V Li-Polymer Replacement Battery (AGPB009-A003)
This 3.7V, 1250mAh Li-Polymer battery replaces the original AGPB009-A003 cell in the Sony Xperia ST27 and ST27i (also sold as the Xperia go and Lotus). It fits the same footprint as the factory cell at 67.40 × 32.55 × 4.50mm and connects to the same three-pin flex connector on the motherboard.
- ST27 / ST27i / Xperia go platform: These variants share the same battery bay geometry, connector pinout, and 3.7V nominal rail. The BMS handshake is handled by the phone's charge IC, not a chip embedded in the battery, so the cell seats and registers without modification.
- Bench tested on actual hardware: We cycled this cell through the ST27i's charge IC and confirmed the BMS accepted charge without triggering an error state. Voltage at full charge held at 4.19–4.20V, consistent with the phone's cutoff threshold.
- Fuel gauge recalibration on first use: On the first discharge cycle after installation, run the phone from 100% down to automatic shutdown — do not interrupt it. This lets the fuel gauge IC map the new cell's discharge curve before Android begins reporting percentage data to the status bar.
Why the Xperia ST27i reports wrong battery percentage after a cell swap
The ST27i uses a coulomb counter integrated into the phone's power management IC, not the battery itself. When you install a new cell, the counter still holds calibration data from the old, degraded cell. That mismatch causes the percentage displayed to jump, stall, or land nowhere near the real state of charge. One complete uninterrupted discharge-to-shutdown followed by a full charge resets the learned curve and brings the readout back in line with actual capacity.
Sudden shutdown at 20–25% on the replacement cell
This happens when the phone's modem or display draws a current spike that the new cell cannot sustain at its present voltage. Li-Polymer cells have a steeper voltage cliff in the lower charge range during the first few cycles — the phone's low-battery cutoff triggers before the gauge catches up. It is not a faulty cell. After two or three full discharge-charge cycles, the cell's internal resistance stabilises and the voltage cliff flattens. If shutdowns continue past the third cycle, check resting voltage — a healthy cell should read above 3.6V when the phone shows 20%.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Sony
- 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
The Xperia ST27i powers on but shuts off the moment I open an app — is the new battery causing this?
Yes, and it is a voltage sag issue on an uncycled cell. A fresh Li-Polymer cell has slightly higher internal resistance than a broken-in one, so a sudden current draw from the modem or GPU pulls the terminal voltage below the phone's cutoff threshold. This typically resolves after two to three full discharge-charge cycles as the cell's internal resistance drops. If it persists after three cycles, measure resting voltage with a multimeter — it should read 3.7V or above after a full charge.
My phone shows 100% immediately after installing the new battery, then the percentage drops to 60% within minutes — what's wrong?
Nothing is wrong with the cell itself. The ST27i's fuel gauge IC is still calibrated to the discharge curve of the old, worn-out cell it just replaced. The coulomb counter is feeding the OS stale reference data. Run the phone from a full charge all the way down to automatic shutdown without interruption, then charge it fully in one unbroken session. That single full cycle gives the fuel gauge IC the data it needs to remap percentage against the new cell's actual capacity.
The phone gets noticeably warm near the battery compartment during the first few charges — is that normal?
It is common on the first one or two charge cycles with a new high-impedance cell. The charge IC has to work harder to push current into a cell that has not yet been conditioned, which generates more heat than usual at the board level. Warmth that fades after the second or third charge is not a concern. If the phone becomes hot to the touch or the charger disconnects and reconnects repeatedly, remove the phone from charge and let it cool to room temperature before continuing.
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