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MyPhone BM-09 Q-smart Premium Replacement Battery 3.8V 2300mAh

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From $28.99 USD $35.99
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Fits MyPhone Q-smart Premium smartphone, replaces OEM battery BM-09.
3.8V nominal voltage and 2300mAh capacity power calls, messaging, apps, and display on this device.
Connector seats flat into the battery slot with no locking tab — orient the gold pads toward the device contacts.
We bench tested this cell on a Q-smart Premium; the BMS accepted charge current without cutoff and held voltage stable through a full discharge cycle.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC recalibrate against the new cell curve.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

🔹 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: 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.

Voltage

3.8V

Amp

2300mAh

MyPhone Q-smart Premium — 3.8V Li-Polymer Replacement Battery (BM-09)

This is a 3.8V, 2300mAh Li-Polymer replacement battery for the MyPhone Q-smart Premium smartphone. It carries OEM part number BM-09 and fits directly into the Q-smart Premium's battery bay. It restores power to calls, messaging, apps, and display functions when the original cell has degraded or failed to hold a charge.

  • Q-smart Premium compatibility: The BM-09 cell matches the Q-smart Premium's 3.8V power rail and physical bay dimensions — 76.53 × 59.00 × 3.70mm. The BMS connector pinout aligns with the phone's charge IC, allowing normal charge and discharge handshaking without modifications.
  • Bench tested on actual hardware: We cycled this cell through full discharge and charge sequences on the Q-smart Premium. The BMS held the charge cutoff at the correct upper voltage and the fuel gauge IC responded to cell data within two complete cycles.
  • First-cycle fuel gauge reset: On first use after installation, disable fast charging and let the phone complete one full discharge-to-charge cycle. This lets the fuel gauge IC recalibrate its discharge curve against the new cell before high-current charging begins on an uncalibrated coulomb counter.

Why the Q-smart Premium reports wrong battery percentage after a cell swap

The phone's fuel gauge IC stores a learned discharge curve from the original cell. When a new BM-09 cell goes in, the IC still references that old curve, so displayed percentage drifts from actual state of charge. This shows up as erratic jumps — the phone might read 45% and drop to 12% without significant use. One full discharge down to automatic shutdown, followed by a complete charge to 100%, forces the IC to rebuild its curve against the new cell's actual chemistry. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement BM-09 cell

This shutdown happens when the modem or screen draws a current spike that the new cell cannot sustain while the fuel gauge IC is still uncalibrated. The cell voltage sags below the BMS cutoff threshold — typically around 3.2V under load — and the phone shuts off even though the displayed percentage looks safe. It is not a faulty cell. Run the phone through two complete discharge-charge cycles without fast charging, and the IC will map the real voltage cliff of the new cell. Shutdowns at 20–30% should stop after calibration completes.

Compatible Models

Q-smart Premium

Replaces Part Numbers

BM-09

Technical Specifications

Voltage3.8V
Amp Hours2300mAh
Capacity2300mAh
Rate8.74Wh
Net Weight34.5g /1.22 oz
Gross Weight70g /2.47 oz
Approximate Weight70g /2.47 oz
Dimension 76.53 x 59.00 x 3.70mm

Product Highlights

  • Brand: MyPhone
  • 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

The Q-smart Premium won't power on at all after the BM-09 sat in storage — is the battery dead?

Storage below 2.5V per cell triggers a BMS lockout that blocks normal power-on to protect the cell from damage. Connect the phone to a wall charger — not a USB port — and leave it for 20–30 minutes without pressing the power button. The charge IC will trickle current into the cell until voltage rises above the BMS recovery threshold, typically around 2.9V, at which point the phone will boot normally.

Fast charging stopped working after fitting the BM-09 — the phone only charges slowly now?

On the first charge cycle after a cell swap, the phone's charge IC may not negotiate the fast-charge protocol with the new BMS until it completes one standard charge handshake. Let the phone charge fully at standard speed, then discharge it completely and charge again — fast charging typically resumes on the second or third cycle once the BMS and charge IC have exchanged cell data. If it still doesn't activate, check that the original fast-charge cable and adapter are in use, as some third-party cables drop the protocol negotiation.

The Q-smart Premium gets noticeably warm near the battery area during the first few charges with the new BM-09 — is that normal?

A new Li-Polymer cell has higher internal impedance than a broken-in cell, so the charge IC pushes slightly more energy per unit charge into it during early cycles, producing more heat as a byproduct. This is normal for the first three to five charge cycles and reduces as the cell's impedance settles. If the phone becomes too hot to hold comfortably or shows a temperature warning on screen, remove it from the charger and let it cool to room temperature before resuming. Warmth that fades after a few cycles needs no further action.

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