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ZTE Nubia Z40 Pro Compatible Battery 3.89V 4900mAh Li3949T44P8h886554

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From $38.99 USD $47.99
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Fits ZTE Nubia Z40 Pro, Z40 Pro 5G, Z40S Pro, Z40S Pro 5G — replaces OEM part Li3949T44P8h886554.
Outputs 3.89V at 4900mAh capacity — supplies 19.06Wh to sustain processor, display, and modem draw under load.
Connector slides into the battery slot at top-left of the mainboard with flat-pin JST contact — locking tab sits flush against the plastic housing lip.
We ran full-discharge cycles on the Nubia Z40 Pro platform; the BMS accepted the new fuel gauge handshake without fault codes or early cutoff events.
On first use after installation, disable fast charging for one complete discharge-charge cycle — this recalibrates the coulomb counter against the new cell discharge curve before high-current USB-PD pushes into an uncalibrated BMS.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

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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.

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⚠️ 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

3.89V

Amp

4900mAh

ZTE Nubia Z40 Pro Series — 3.89V Li-Polymer Replacement Battery (Li3949T44P8h886554)

This is a 3.89V, 4900mAh (19.06Wh) Li-Polymer cell for the ZTE Nubia Z40 Pro, Nubia Z40 Pro 5G, Nubia Z40S Pro, and Nubia Z40S Pro 5G. It replaces the original OEM cell when the existing battery has degraded and can no longer hold charge through a full day of use. The OEM part number is Li3949T44P8h886554.

  • Z40 Pro and Z40S Pro cross-compatibility: Both the Z40 Pro and Z40S Pro lines share the same physical footprint (86.40 × 64.90 × 5.30mm), connector pinout, and BMS handshake protocol — so the same cell fits all four variants without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Z40 Pro unit. The BMS accepted the cell on first connection, voltage stabilised at 3.89V nominal, and charge termination triggered correctly at full capacity without overcharge events.
  • Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard speed. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging is introduced to an uncalibrated cell.

Sudden shutdown at 20–30% on the Nubia Z40 Pro after cell replacement

The Z40 Pro's Snapdragon platform draws a sharp current spike during 5G modem handoffs and high-refresh display activity. A new cell with an uncalibrated fuel gauge IC can report 25% remaining while actual cell voltage has already dropped below the BMS cutoff threshold under that load. The BMS reads a real undervoltage event and shuts the device down — even though the percentage shown looked safe. One full discharge-charge cycle at standard charge speed recalibrates the coulomb counter and eliminates most of these false-floor shutdowns.

USB-PD or proprietary fast charge not activating on the first cycle after swap

ZTE's fast charge protocol negotiates between the charge IC on the motherboard and the BMS in the battery. On a fresh cell, the BMS starts in a conservative low-current mode until it has completed at least one full charge cycle and confirmed cell integrity. Plugging in a fast charger immediately after installation often results in standard 5V/1A charging only — this is normal BMS behaviour, not a fault with the charger or the cell. After the first complete cycle, reconnect the fast charger and the protocol negotiation will proceed at full current.

Compatible Models

Nubia Z40 Pro Nubia Z40 Pro 5G Nubia Z40S Pro Nubia Z40S Pro 5G NX701J NX702J

Replaces Part Numbers

Li3949T44P8h886554

Technical Specifications

Voltage3.89V
Amp Hours4900mAh
Capacity4900mAh
Rate19.06Wh
Net Weight70g /2.47 oz
Gross Weight120g /4.23 oz
Approximate Weight120g /4.23 oz
Dimension 86.40 x 64.90 x 5.30mm

Product Highlights

  • Brand: ZTE
  • 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 Nubia Z40 Pro shuts off around 25% even though the new battery is fully charged — what's causing that?

This is a voltage cliff issue. The new cell's discharge curve hasn't been mapped by the fuel gauge IC yet, so the phone's percentage reading lags behind the real cell voltage. Under 5G modem load or screen-on bursts, the actual voltage drops below the BMS cutoff while the display still shows 25%. Run one full discharge down to automatic shutdown, then charge to 100% without interruption at standard speed — this recalibrates the coulomb counter and fixes the false-floor shutdowns.

The phone was stored with the new battery installed for a few weeks and now it won't turn on at all — is the battery dead?

Li-Polymer cells self-discharge in storage, and if the cell dropped below approximately 2.5V the BMS enters lockout mode to prevent damage — the phone will not respond to the power button. Connect the original ZTE charger (not a fast charger) and leave it for 20–30 minutes without attempting to power on. The charge IC will trickle current into the cell until voltage rises above the BMS recovery threshold, after which normal charging resumes and the device will boot.

After fitting the replacement cell, the battery percentage jumps around — it reads 60%, then drops to 40%, then climbs back up without charging. Is the battery faulty?

The fuel gauge IC on the Z40 Pro's motherboard was calibrated to the old cell's specific impedance and discharge curve. When a new cell is installed, the IC has no accurate reference data yet, so it estimates state-of-charge poorly and percentage readings swing erratically. This is not a cell defect. Complete two full discharge-charge cycles at standard charge speed — by the end of the second cycle the fuel gauge IC will have enough data to track the new cell accurately and the jumping will stop.

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