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Huawei Band 7 Replacement Battery HB351731EFW 3.87V 180mAh

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From $33.99 USD $41.99
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Fits Huawei Band 7, Band 6, Band 6 Pro smartwatches; replaces OEM part HB351731EFW.
Rated 3.87V at 180mAh; this lithium-polymer cell powers display, heart rate sensor, and activity tracking on your Band.
Connector is a two-pin pogo pad; align flat contacts straight into the watch housing socket without forcing.
We bench tested this cell on Band 7 firmware; the fuel gauge IC initialized correctly after seating and showed stable voltage under continuous HR monitoring load.
After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before wearing—the fuel gauge cannot calibrate without a full initial charge cycle from the new pack.
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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

3.87V

Amp

180mAh

Huawei Band 7 / Band 6 Series — 3.87V Li-Polymer Replacement Battery (HB351731EFW)

This is a 180mAh (0.7Wh) 3.87V lithium-polymer cell that replaces the OEM HB351731EFW battery in the Huawei Band 7, Band 6, and Band 6 Pro. It restores power to the display, optical heart rate sensor, and activity tracking modules. Physical dimensions are 29.40 × 16.30 × 3.40mm — confirm clearance before ordering if your unit has been previously repaired.

  • Band 7, Band 6, Band 6 Pro compatibility: All three models share the HB351731EFW cell format, the same 3.87V charging rail, and an identical footprint. The BMS termination voltage and charge curve are consistent across the group, so one cell covers all three.
  • Bench tested on actual hardware: We ran the HB351731EFW on the Band 7 platform and confirmed the BMS accepted the cell without a fault flag. Charge termination triggered correctly at 4.35V, and the fuel gauge IC updated its state-of-charge reading after a full charge cycle.
  • Post-swap charge requirement: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on this platform loses its calibration reference when the original cell is disconnected. Without a full charge cycle from near-zero, the percentage readout will be unreliable.

Smartwatch showing 0% immediately after battery swap

This happens because the fuel gauge IC — a small dedicated chip separate from the main SoC — stores a learned charge table for the old cell. When the cell is swapped, that reference is gone and the IC defaults to 0% or shows a flat, incorrect readout. The fix is straightforward: connect the watch to its charger right after reassembly and let it charge to 100% without interruption. Once the gauge IC completes a full cycle from near-zero, it recalibrates against the new cell's actual capacity. After that first full charge, the percentage display will track correctly.

Watch not pairing with the phone app after battery replacement

Removing the battery cuts power to the Bluetooth controller and clears its active session keys. The Huawei Health app holds the old session in memory and may show the device as connected while the watch itself sees no active pairing. Open the Huawei Health app, go to device settings, tap "Unpair device," then initiate a fresh pairing from the Band's Bluetooth menu. The watch must be fully powered on — not just showing the boot logo — before the pairing handshake will complete.

Compatible Models

Band 7 Band 6 Band 6 Pro

Replaces Part Numbers

HB351731EFW

Technical Specifications

Voltage3.87V
Amp Hours180mAh
Capacity180mAh
Rate0.7Wh
Net Weight5g /0.18 oz
Gross Weight30g /1.06 oz
Approximate Weight30g /1.06 oz
Dimension 29.40 x 16.30 x 3.40mm

Product Highlights

  • Brand: Huawei
  • 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

My Huawei Band 7 battery drains completely within a single day after the swap — is something wrong with the new cell?

A new cell on a smartwatch platform often draws more current in the first few days because the fuel gauge IC is still profiling the cell's impedance. Check whether always-on display and continuous heart rate monitoring are both enabled — those two features together pull significantly more current than interval-based tracking. Turn continuous HR monitoring to interval mode (every 10 minutes) and see whether multi-day drain returns within 3–5 charge cycles. If drain remains unusually fast after a week, check that the charge contacts are seated flush and the battery reached a full 4.35V termination on the first charge.

The magnetic charger doesn't seem to be charging the watch after I put it back together — the charge indicator never appears.

This is almost always a contact alignment issue from reassembly. The magnetic charger pads on the Band 7 require the rear housing to sit flush; even a 0.5mm shift from a slightly unseated battery can lift the charge contacts out of range. Power the watch off, press the rear cover firmly until it clicks, then re-seat the charger. If the charging screen still doesn't appear, clean the gold pogo contacts on both the watch and charger with a dry cotton swab and try again.

The heart rate sensor seems to run constantly and gets warm on my wrist — did the replacement battery trigger this?

The optical HR sensor does not change its behaviour based on which cell is installed. Continuous or elevated HR sensor activity is controlled by the watch firmware and the settings in the Huawei Health app. If the sensor is running non-stop, check that "Continuous heart rate monitoring" is set to interval mode rather than real-time in the app's health monitoring settings. A factory reset of the band is not necessary — adjusting that single setting in the app is enough to return the sensor to its normal duty cycle.

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