About this replacement
LG Watch R / Watch Urbane 3G — 3.85V Li-Polymer Replacement Battery (BL-S2)
This is a 3.85V, 280mAh Li-Polymer cell replacing the BL-S2 battery in the LG Watch R (W100) and Watch Urbane 3G. Both watches use the same connector, cell footprint, and BMS handshake, making this cell a direct fit across the platform. Swap it when the original cell can no longer hold charge through normal daily use.
- Watch R and Urbane 3G compatibility: Both models share the same 3.85V rail, physical cell dimensions (38.30 × 23.20 × 3.20mm), and BL-S2 connector. The BMS on each platform negotiates the same charge termination voltage, so one cell covers the full lineup without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Watch R platform. The BMS accepted the cell without fault flags, charge termination triggered correctly at 4.35V, and the fuel gauge IC re-calibrated after one full charge cycle from near-depleted.
- Fuel gauge calibration after swap: Place the watch on its magnetic charger immediately after fitting this cell and charge it fully to 100% before first use. The LG Watch R's fuel gauge IC loses its state-of-charge reference when the cell is removed. Without a full charge cycle from near-zero, the gauge will report inaccurate percentages — often showing 0% or jumping erratically.
Why the Watch R's charge contacts stop delivering current after reassembly
The Watch R charges through a magnetic pogo-pin cradle that requires precise rear-case alignment. If the rear cover is even slightly off-centre after reassembly, the spring contacts miss their pads and the watch receives no charge current. The watch will show the charging animation briefly — triggered by magnetic attachment — then stall at the same battery percentage. Re-seat the rear cover, confirm it clicks flush on all sides, then place it back on the charger and watch for a steady charge indicator within 30 seconds.
Watch R not pairing to the phone after battery replacement
Removing the battery cuts power to the BLE controller, which drops the active pairing session stored in the watch's volatile memory. The phone retains the old device record, but the watch no longer has a matching session key. Go into your phone's Bluetooth settings, forget the LG Watch R entry, then re-pair from scratch through the LG Watch Manager or Android Wear app. Do not attempt a re-pair until the watch has completed its first full charge cycle post-swap.