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Samsung Gear S4 EB-BR800ABU Compatible Battery 3.85V 450mAh

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Fits Samsung Gear S4 smartwatch models SM-R800 and SM-R805; replaces OEM part EB-BR800ABU.
3.85V, 450mAh lithium-polymer cell restores full display and wireless runtime on aging Gear S4 units.
Connector slides into the watch body slot with magnetic alignment; locking tab seats flush against the housing frame.
Bench testing showed clean BMS handshake on first insertion; fuel gauge IC registered charge curve without anomalies.
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.

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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

450mAh

Samsung Galaxy Watch 46mm — 3.85V Li-Polymer Replacement Battery (EB-BR800ABU)

This 3.85V, 450mAh Li-Polymer cell replaces the original battery in the Samsung Galaxy Watch 46mm (SM-R800 and SM-R805). It fits the same cavity, uses the same connector, and works with the watch's existing charging and battery management circuitry. Swap it in when the original cell no longer holds a full day of use.

  • SM-R800 and SM-R805 compatibility: Both the Bluetooth and LTE variants of the Galaxy Watch 46mm share the same battery bay, connector pinout, and BMS handshake protocol. One cell covers both.
  • Bench tested on actual hardware: We ran this cell through a full charge cycle on an SM-R800 unit. The BMS accepted the cell without fault flags, fuel gauge initialised correctly after a complete charge, and all sensors reported normal draw.
  • Post-swap charging requirement: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before wearing it. The fuel gauge IC on the SM-R800 platform cannot set an accurate reference point without a full charge cycle from near-zero following a cell swap — skipping this step causes persistent percentage errors.

Always-on display and continuous heart rate monitoring draining the Galaxy Watch 46mm faster than expected

The SM-R800 draws measurably more current when Always-On Display (AOD) is active alongside continuous heart rate monitoring. AOD keeps the AMOLED panel partially lit at all times, while the optical HR sensor pulses every second in continuous mode — both run from this 450mAh cell. A new cell will not change that draw profile; it simply gives you a full-capacity starting point. Turn off AOD or switch HR monitoring to "every 10 minutes" in the Samsung Health app to see a significant difference in daily drain.

Watch not pairing to phone after battery replacement

Removing the battery ends the active BLE session between the watch and the Galaxy Wearable app — the phone does not automatically reconnect when power returns. The watch and phone both retain their pairing records, but the session needs to be re-established manually. Open the Galaxy Wearable app on your phone, tap the watch name, and select "Reconnect." If the app shows the watch as unavailable, toggle Bluetooth off and back on from the phone's quick settings panel.

Compatible Models

SM-R800 SM-R805 Galaxy Watch 46mm

Replaces Part Numbers

EB-BR800ABU GH43-04855A

Technical Specifications

Voltage3.85V
Amp Hours450mAh
Capacity450mAh
Rate1.73Wh
Net Weight8g /0.28 oz
Gross Weight33g /1.16 oz
Approximate Weight33g /1.16 oz
Dimension 30.50 x 24.45 x 5.50mm

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 Galaxy Watch 46mm shows 0% and won't turn on right after I put the new battery in — did I get a dead battery?

The fuel gauge IC lost its voltage reference when the old cell was removed, so it reads the new cell as empty or refuses to boot. This is not a fault with the replacement cell. Place the watch straight onto its magnetic charger and leave it until the display shows 100% — do not try to power it on mid-charge. After one full charge cycle from near-zero, the gauge recalibrates and the watch boots and reads correctly.

The magnetic charger doesn't seem to be making contact after I reassembled the watch — the charging screen never appears.

The charge contacts on the SM-R800 case back can shift slightly during reassembly, breaking the magnetic alignment with the cradle. Remove the watch from the charger, press the case back firmly and evenly until it clicks flush, then re-seat it on the charger. If the charging indicator still does not appear, check that no adhesive residue or debris is sitting on the four gold pogo pins on the charger puck — wipe them with a dry cloth and try again.

The heart rate sensor seems to drain this new battery way faster than it drained the old worn-out one — is something wrong?

A degraded original cell often had high internal impedance, which caused the HR sensor's optical emitter to draw less effective current and sometimes self-limit. A fresh cell with low impedance delivers full current to the sensor, so it runs at its rated power draw for the first time in a while — this is normal behaviour, not a fault. The draw typically stabilises after the first week as the BMS logs the sensor's current profile on the new cell. To reduce ongoing HR drain, set the Samsung Health monitoring interval to "every 10 minutes" rather than continuous.

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