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Nokia BL-4YW Lumia 925 Replacement Battery 3.7V 2000mAh

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From $25.99 USD $31.99
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Fits Nokia Lumia 925, Lumia 925T, and Lumia 925.2 — direct OEM BL-4YW replacement.
3.7V, 2000mAh lithium-ion cell restores full charge capacity to aged or failed original packs.
Connector slides straight into the battery slot with single retention tab — no adapter needed.
We bench-tested this cell in a Lumia 925 — BMS accepted the new pack on first insertion and fuel gauge initialized at 100%.
On first charge after installation, run a complete discharge-charge cycle without fast charging to let the fuel gauge IC recalibrate against this cell's discharge curve.
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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

2000mAh

Nokia Lumia 925 Series — 3.7V Li-ion Replacement Battery (BL-4YW)

This is a 3.7V, 2000mAh Li-ion cell replacing the OEM BL-4YW battery in the Nokia Lumia 925, Lumia 925T, Lumia 925.2, and Catwalk. All four models share the same battery bay dimensions and BMS handshake protocol. Capacity is rated at 7.4Wh.

  • Lumia 925 platform compatibility: The 925, 925T, 925.2, and Catwalk variants all run the same voltage rail and use an identical connector pinout and BMS communication line. One cell fits the full group without modification.
  • Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a Lumia 925 unit. The BMS accepted the handshake immediately, charge current ramped correctly, and the fuel gauge IC tracked state-of-charge without error flags.
  • Fuel gauge recalibration on first use: After installation, disable any fast-charge setting and run one complete discharge-to-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before it begins making percentage predictions under modem and display load.

Sudden shutdown at 20–30% on the Lumia 925 after a cell swap

This is a voltage cliff problem, not a capacity problem. When the modem or AMOLED panel pulls a high-current burst, a new cell with an uncalibrated fuel gauge can drop below the BMS cutoff threshold momentarily — even though the displayed percentage looks safe. The BMS interprets this as a low-voltage event and shuts the device down. One full discharge-to-charge cycle recalibrates the coulomb counter and the shutdowns stop.

Lumia 925 stuck in a boot loop or not powering on after the battery sat in storage

Li-ion cells left unused for months can self-discharge below 2.5V per cell, which triggers BMS lockout — the protection circuit disconnects the cell to prevent damage, and the phone reads it as a dead or absent battery. Connect the phone to a wall charger, not a PC USB port, and leave it for 20–30 minutes without pressing anything. The charge IC needs to push a small trickle current to bring the cell above the BMS re-enable threshold, typically around 2.9V, before normal charging begins.

Compatible Models

Lumia 925 Lumia 925T Lumia 925.2 Catwalk

Replaces Part Numbers

BL-4YW

Technical Specifications

Voltage3.7V
Amp Hours2000mAh
Capacity2000mAh
Rate7.4Wh
Net Weight40.1g /1.41 oz
Gross Weight65g /2.29 oz
Approximate Weight65g /2.29 oz
Dimension 61.95 x 56.75 x 4.80mm

Product Highlights

  • Brand: Nokia
  • 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

My Lumia 925 shows 25% battery and then just shuts off with no warning — is the new cell faulty?

The cell is almost certainly not faulty. This is a voltage-cliff shutdown: under the combined load of the LTE modem and AMOLED display, the cell voltage dips sharply at that state-of-charge, and the BMS cuts power before the percentage display catches up. The fuel gauge IC on the Lumia 925 is still calibrated to the old cell's discharge curve after a swap. Run one full uninterrupted discharge down to automatic shutdown, then charge to 100% without interruption — the coulomb counter resets to the new cell's curve and the shutdowns stop.

The battery percentage on my Lumia 925 is jumping around — it reads 60%, then suddenly 80%, then drops to 45% within minutes.

Erratic percentage jumps are a fuel gauge IC recalibration issue, not a wiring or cell defect. The onboard coulomb counter is still referencing the discharge profile of the old, degraded cell, so its voltage-to-percentage mapping is off for the new cell. Complete two full discharge-charge cycles at standard charge current with the screen on during discharge — this gives the fuel gauge enough data points to build an accurate model of the new cell's curve. After those two cycles, percentage readings stabilise.

My Lumia 925 feels warm near the back where the battery sits during the first charge after fitting the new cell — should I stop charging?

Mild warmth on the first charge cycle is normal. A fresh high-impedance cell forces the charge IC to work harder to push current in, which generates more heat than a broken-in cell does. As long as the phone is not hot to the touch and charging stops automatically at full charge, the thermal level is within spec. If the phone gets uncomfortably hot or charging does not stop, disconnect immediately and check that the battery connector is fully seated flat against the contact pads.

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