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Samsung Gear S2 3G Replacement Battery 3.7V 300mAh EB-BR730ABE

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Fits Samsung Gear S2 3G smartwatch and replaces OEM battery EB-BR730ABE.
This 3.7V, 300mAh Li-Polymer cell restores full charge capacity for fitness tracking and notifications.
Connector seats into the watch housing with alignment pins; magnetic charger contacts must align flush.
Bench testing showed the BMS fuel gauge required a full charge cycle to recalibrate after swap.
After fitting the new cell, place the watch on its charger immediately and charge to 100% before first use — the fuel gauge IC on smartwatch platforms cannot calibrate without a full charge cycle from near-zero after a cell swap.
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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

300mAh

Samsung Gear S2 3G — 3.7V Li-Polymer Replacement Battery (EB-BR730ABE)

This is a 3.7V, 300mAh Li-Polymer cell that fits the Samsung Gear S2 3G smartwatch. It covers SM-R730, SM-R730A, and related variants sharing the EB-BR730ABE form factor. Capacity matches the original spec at 1.11Wh — no upsizing claims, no inflated figures.

  • SM-R730 series fit: The SM-R730 and SM-R730A share the same battery bay dimensions, connector orientation, and BMS handshake. Swapping between these variants does not require any firmware change — the cell seats identically and the charge controller sees it as a valid source.
  • Bench tested on actual hardware: We cycled this cell through the Gear S2 3G charge controller and confirmed the BMS accepted the cell without fault codes. Charge termination triggered cleanly at full voltage — no float-charge stall observed.
  • Post-swap charge requirement: After fitting the new cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on the Gear S2 3G cannot calibrate its state-of-charge reference without a complete charge cycle from near-zero after a cell swap.

Why the Gear S2 3G charge controller rejects a new cell on first connect

When cell voltage drops below approximately 2.5V during storage or shipping, the Gear S2 3G BMS treats the cell as faulted and refuses to begin a standard charge cycle. The magnetic charger appears to sit idle — no vibration, no charge icon. Placing the watch on the charger for 10–15 minutes allows trickle pre-charge to bring the cell above the 2.8V threshold, after which normal CC/CV charging resumes automatically.

Watch showing 0% and refusing to boot after battery swap

This happens because the fuel gauge IC lost its reference voltage when the original cell was removed. The new cell is physically charged, but the IC has no stored baseline to map capacity against — it reads zero. Do not attempt repeated reboots. Place the watch on the charger and leave it connected until the display reports 100%. Once that full-charge reference point is written to the IC, the percentage readout will track accurately on subsequent cycles.

Compatible Models

Gear S2 3G Galaxy Gear S2 3G SM-R730 SM-R730A SM-R730T SM-R730S SM-R730V SM-R735

Replaces Part Numbers

EB-BR730ABE GH43-04538B

Technical Specifications

Voltage3.7V
Amp Hours300mAh
Capacity300mAh
Rate1.11Wh
Net Weight8g /0.28 oz
Gross Weight33g /1.16 oz
Approximate Weight33g /1.16 oz
Dimension 31.35 x 19.90 x 5.00mm

Product Highlights

  • Brand: Samsung
  • 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 Gear S2 3G battery is draining completely in one day — why is this happening after the swap?

A new cell on the Gear S2 3G can show elevated drain in the first few days because the fuel gauge IC is still building its capacity reference after the swap. Check whether always-on display and continuous heart rate monitoring are both active — those two features together pull consistent current and will drain a 300mAh cell significantly faster than intermittent-use settings. Disable continuous HR monitoring in the Samsung Gear app and switch the display to gesture-on mode. Drain should stabilise after two to three full charge cycles once the fuel gauge has calibrated.

The heart rate sensor seems to be running constantly and killing the battery — is the new cell at fault?

The new cell is not at fault. On a fresh cell with a higher resting impedance than a degraded original, the Gear S2 3G's sensor firmware can interpret the voltage response as an unstable read and increase sampling frequency to compensate. This typically self-corrects within the first week as the cell settles. Open the Samsung Health app on the paired phone, set HR monitoring to "manually" rather than "auto," and check again after five full charge cycles — sensor current draw should drop to normal polling intervals by then.

My Gear S2 3G won't pair with my phone after replacing the battery — Bluetooth just keeps searching.

Removing the battery ends the active BLE session between the watch and the Galaxy Wearable app, and the session token is not automatically re-established on power-up. On the phone, open the Galaxy Wearable app, go to About Watch → Disconnect, then remove the watch from the phone's Bluetooth paired devices list entirely. Restart the watch, open the Galaxy Wearable app, and pair from scratch as a new device. The watch will reconnect and sync normally once a clean pairing handshake is completed.

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