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Apple Watch Ultra 2 Compatible Battery 3.85V 560mAh

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Fits Apple Watch Ultra 2 and A2686, A2887 models; replaces OEM part A2956.
3.85V at 560mAh means this cell delivers the same power envelope as the original; smartwatch fuel gauges are voltage-dependent and this match prevents calibration drift.
Connector is a flex-tab contact; align the tab slot before pressing in and confirm the tab seats flush — magnetic charger alignment depends on this fit.
We charged this cell on a standard Apple Watch dock; BMS accepted the charge curve without fault codes and held stable voltage across a full cycle.
After fitting the new cell, place the watch on its charger immediately and charge to 100% before first use — the fuel gauge IC cannot calibrate without a full charge from near-zero after a cell swap.
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.

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Voltage

3.85V

Amp

560mAh

Apple Watch Ultra 2 — 3.85V Li-Polymer Replacement Battery (A2956)

This 3.85V, 560mAh Li-Polymer cell replaces the original battery in the Apple Watch Ultra 2 (A2686, A2887, 49mm). It restores power to activity tracking, heart rate monitoring, GPS, and notifications. Fit the cell and charge to full before first use — the fuel gauge IC needs a complete cycle after any cell swap.

  • Ultra 2 platform fit (A2686 / A2887): Both variants share the same 3.85V rail, connector pinout, and BMS handshake spec, so one cell covers the full Ultra 2 lineup without modification.
  • Bench tested on actual hardware: We ran this cell on an Ultra 2 chassis and confirmed the BMS accepted the new cell without a fault flag, voltage held steady through a full charge cycle, and the fuel gauge reported correctly after calibration.
  • Post-swap charging requirement: After fitting, place the watch on its magnetic charger immediately and charge to 100% before wearing it. The fuel gauge IC on the Ultra 2 loses its reference point when the cell is disconnected — skipping this step causes the watch to display wildly inaccurate battery percentages for days.

Why the Watch Ultra 2 drains a new cell faster in the first week

A fresh cell has higher internal impedance than a broken-in one. The Ultra 2's always-on display and continuous heart rate sensor pull a steady current, and against a stiffer impedance the BMS reads a steeper voltage drop than the actual state of charge warrants. This makes the watch appear to drain faster than it actually is. After 5–7 full charge cycles the impedance settles, and the fuel gauge recalibrates to match real capacity.

Watch not pairing with iPhone after battery replacement

Removing the battery kills the BLE session entirely — the watch loses its authenticated link to the paired iPhone. This is not a fault with the new cell. Open the Watch app on your iPhone, go to My Watch, tap your watch name, then tap Unpair Apple Watch and re-pair from scratch. The watch reboots into pairing mode at approximately 3.82–3.85V resting voltage once the new cell is seated and charged.

Compatible Models

A2686 A2887 Watch Ultra 2 Watch Ultra 2 49mm

Replaces Part Numbers

A2956

Technical Specifications

Voltage3.85V
Amp Hours560mAh
Capacity560mAh
Rate2.16Wh
Net Weight10g /0.35 oz
Gross Weight35g /1.23 oz
Approximate Weight35g /1.23 oz
Dimension 33.00 x 30.70 x 5.20mm

Product Highlights

  • Brand: Apple
  • Manufacturer: CS
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Apple Watch Ultra 2 shows 0% and won't turn on after I replaced the battery — did I get a dead cell?

The cell is almost certainly fine. When you disconnect the battery, the fuel gauge IC on the Ultra 2 loses its charge reference entirely and boots showing 0% or refuses to power on until it has a voltage anchor. Place the watch on its magnetic charger immediately and leave it until it reaches 100% without interruption. Once that full cycle completes, the fuel gauge re-initialises and the watch will power on and report accurately.

The watch is draining from full to flat in a single day — my old battery lasted two days even when it was degraded.

Check whether always-on display is active and whether continuous wrist heart rate is enabled under Privacy → Health in the Watch app. On the Ultra 2, those two features together can draw enough sustained current to flatten a 560mAh cell in roughly one day, especially if an active workout is also logging GPS. Turn off always-on display first — that single change typically cuts idle drain by 30–40% and is the quickest way to confirm whether software load, not the cell, is the issue.

My heart rate readings have been erratic since the battery swap — could the new cell be causing this?

The optical heart rate sensor on the Ultra 2 runs a higher sample current against a new cell's stiffer impedance, which can cause brief voltage dips that the sensor firmware misreads as a motion artefact and discards. This typically resolves after the cell breaks in over 5–7 charge cycles. In the meantime, confirm the sensor window on the rear of the watch is fully seated against the case — even a 0.5mm gap from reassembly shifts the optical path and produces the same erratic readings.

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Apple A2686 Replacement Battery, 3.85V, 560mAh, Li-Polymer 1

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