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Apple Watch Series 6 44mm Compatible Battery A2327 3.85V 300mAh

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From $38.99 USD $47.99
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Fits Apple Watch Series 6 44mm, replaces OEM part A2327.
3.85V, 300mAh lithium-polymer cell powers fitness tracking, heart rate monitoring, notifications, and Siri on this smartwatch.
Connector seats flat against the watch's internal dock with magnetic alignment — no locking tab, requires precision seating.
We ran a full charge cycle on test hardware; the fuel gauge IC initialized correctly and held voltage stable under mixed load.
After fitting this cell, place the watch on its charger immediately and charge to 100% before first use — the fuel gauge cannot calibrate without a full charge cycle from near-zero after a swap.
Delivery time

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

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

3.85V

Amp

300mAh

Apple Watch Series S6 44mm — 3.85V Li-Polymer Replacement Battery (A2327)

This 3.85V, 300mAh Li-Polymer cell is a direct swap for the Apple Watch Series 6 44mm. It replaces part number A2327 — the original cell Apple fits at the factory. Voltage, dimensions (27.70 × 20.10 × 4.40mm), and connector all match the OEM specification.

  • Series 6 44mm platform fit: The S6 44mm and 40mm share the same chassis generation but carry different cell footprints and capacities. This cell is sized and rated for the 44mm case only — the 40mm uses a different part.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Series 6 44mm unit. The BMS accepted the cell, reported state-of-charge correctly after a full charge cycle, and held voltage under continuous heart rate and GPS polling without dropping below the BMS cutoff threshold.
  • Post-swap charging requirement: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before use. The fuel gauge IC loses its reference point when the original cell is removed. Without a full charge cycle from near-zero, watchOS will report inaccurate battery percentages — sometimes 0% on a charged cell.

Why the Series 6 fuel gauge IC loses calibration after a cell swap

The Apple Watch Series 6 uses a coulomb-counting fuel gauge IC to track battery state. This IC holds a learned capacity model built from the original cell's charge and discharge history. When the cell is physically removed, that reference is lost — the IC starts with no baseline. A single full charge cycle from near-zero allows the IC to re-anchor its model to the new cell's actual capacity, after which percentage readings stabilise.

Watch not pairing with iPhone after battery replacement

Removing power during a swap terminates the active Bluetooth Low Energy session between the watch and the paired iPhone. The watch does not automatically re-establish this session on reboot — it presents as an unpaired device. To fix this, open the Watch app on the iPhone, go to My Watch → All Watches, tap the watch name, select Unpair Apple Watch, then re-pair from scratch. This resets the BLE handshake and restores full connectivity.

Compatible Models

Watch Series S6 44mm

Replaces Part Numbers

A2327

Technical Specifications

Voltage3.85V
Amp Hours300mAh
Capacity300mAh
Rate1.16Wh
Net Weight5g /0.18 oz
Gross Weight30g /1.06 oz
Approximate Weight30g /1.06 oz
Dimension 27.70 x 20.10 x 4.40mm

Product Highlights

  • Brand: Apple
  • 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 Apple Watch Series 6 shows 0% and won't turn on after fitting the new A2327 battery — did I get a dead cell?

The cell is almost certainly fine. The fuel gauge IC on the Series 6 loses its charge reference the moment the old cell is disconnected, so it reads 0% regardless of actual cell voltage. Place the watch flat on its magnetic charger without pressing any buttons and leave it for at least 30 minutes — the watch should boot and begin reporting charge normally. If the screen stays dark past that point, check that the charge contacts on the back of the watch are fully seated against the charger puck.

Battery on my Series 6 is draining in a single day after the swap — the old one used to last two days.

Always-on display combined with continuous heart rate monitoring creates a sustained current draw that will expose any fuel gauge miscalibration as apparent rapid drain. Run the watch through two complete charge cycles — charge to 100%, use normally until low, then charge to 100% again — before drawing conclusions. After the second cycle the IC recalibrates to the new cell's actual 300mAh capacity and drain rate reports will stabilise. If drain remains abnormal after two full cycles, check that Background App Refresh and Always-On Display are not both active simultaneously in Watch settings.

The magnetic charger keeps losing contact with my Series 6 since I replaced the battery — is the back cover not sitting flush?

A back cover that is not fully re-adhered after a battery swap sits fractionally proud of the case, shifting the charge coil position enough to break the magnetic charger's alignment. Press the back cover firmly around its full perimeter and confirm it clicks flush with the case before placing it on the charger. If the gap reappears, the adhesive gasket needs replacing — reusing the original adhesive after a swap rarely holds reliably. Once the cover is flush, the puck should snap to centre and hold without adjustment.

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