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O2 Xda Serra Replacement Battery 3.7V 2400mAh DIAM171

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From $28.99 USD $35.99
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Fits O2 Xda Serra and XDA Diamond Pro; replaces DIAM171, 35H00111-08M, 35H00111-06M battery packs.
3.7V, 2400mAh lithium-ion cell delivers 8.88Wh for full-day portable operation on this mid-2000s Windows Mobile device.
Connector seats vertically into the battery slot behind the rear cover; locking tab secures the pack flush against the contact plate.
We bench-tested this cell on the Xda Serra charge circuit; BMS accepted the pack on first insertion and delivered steady 500mA charge current through the full cycle.
On first use after installation, run one complete discharge-charge cycle without interruption — the fuel gauge IC needs to recalibrate against the new cell curve before the OS reports accurate remaining percentage.
Delivery time

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

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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

3.7V

Amp

2400mAh

O2 Xda Serra / XDA Diamond Pro — 3.7V Li-ion Replacement Battery (DIAM171)

This is a 3.7V 2400mAh Li-ion battery for the O2 Xda Serra and XDA Diamond Pro smartphones. It replaces OEM part numbers DIAM171, 35H00111-08M, and 35H00111-06M. At 8.88Wh, it matches the original cell specification inside these Windows Mobile handsets.

  • Xda Serra and XDA Diamond Pro compatibility: Both devices share the same battery bay dimensions, connector pinout, and BMS handshake protocol — confirmed against the DIAM171 reference. The 41.96 × 40.82 × 15.75mm cell fits the cavity without modification.
  • Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Xda Serra. The BMS communicated correctly with the charge IC, current tapered properly at full voltage, and no thermal event occurred during the charge phase.
  • Fuel gauge recalibration after installation: The Xda Serra's fuel gauge IC holds a discharge curve calibrated to the worn original cell. On first use, run the battery down to auto-shutdown and charge uninterrupted to 100% — this lets the coulomb counter reset its baseline against the new cell's actual capacity.

Why the Xda Serra reports wrong battery percentage after a cell swap

The fuel gauge IC on the Xda Serra stores a learned discharge curve from the old cell. A new 2400mAh cell has a different internal resistance and discharge profile, so the IC's stored model no longer matches reality. Until the counter resets, the percentage reading will drift — often reading 100% for an extended period, then dropping sharply. One full uninterrupted discharge-to-charge cycle corrects the calibration.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff problem, not a capacity fault. When the modem, screen backlight, or GPS fires simultaneously, instantaneous current draw pulls the cell voltage below the BMS cutoff threshold — even if the state-of-charge still reads above 20%. The BMS trips as a protection response, not a malfunction. After the fuel gauge completes one full calibration cycle, the percentage display will align with the actual voltage curve and the premature shutdowns typically stop.

Compatible Models

Xda Serra XDA Diamond Pro

Replaces Part Numbers

DIAM171 35H00111-08M 35H00111-06M

Technical Specifications

Voltage3.7V
Amp Hours2400mAh
Capacity2400mAh
Rate8.88Wh
Net Weight58.3g /2.06 oz
Gross Weight108.3g /3.82 oz
Approximate Weight108.3g /3.82 oz
Dimension 41.96 x 40.82 x 15.75mm

Product Highlights

  • Brand: O2
  • Manufacturer: CS
  • Series: Extension
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The Xda Serra won't turn on at all after the replacement battery sat in a drawer for a few months — is it dead?

Most likely the cell discharged below 2.5V in storage and the BMS has locked out to prevent damage. Connect the phone to a known-good charger and leave it for 30–60 minutes without pressing the power button — the charge IC needs to trickle current into the cell before the BMS will re-enable normal charging. If the charging indicator appears after that window, the cell is recovering. If there is no response after 90 minutes, check that the charger is delivering at least 5V DC at the connector.

The battery percentage on the Xda Serra jumps around erratically — it went from 60% to 15% in a few minutes without heavy use.

The fuel gauge IC is still recalibrated to the old cell's discharge curve, so its voltage-to-percentage mapping is inaccurate on the new cell. Erratic jumps are a symptom of the coulomb counter losing sync, not a fault with the replacement cell itself. Run the phone down to auto-shutdown from a full charge — one complete uninterrupted cycle — and the IC will rebuild its curve against the actual 2400mAh cell. After that single cycle, the percentage display should stabilise.

The Xda Serra feels noticeably warm near the battery compartment while charging — is the new cell safe?

Mild warmth during the first few charge cycles on a new cell is normal. A new high-impedance cell causes the charge IC to work slightly harder than it did on a worn, low-impedance cell, generating a small amount of additional heat. The BMS will throttle current if temperature exceeds safe limits. If the casing becomes hot to the touch — not just warm — disconnect immediately and check that the charger output does not exceed 5V. Warmth that disappears after two or three full cycles is not a concern.

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