Mini Keyboard RT-MWK08 Replacement Battery 3.7V 900mAh

Mini Keyboard RT-MWK08 — 3.7V Li-ion Replacement Battery (SL-1102A)

This 3.7V 900mAh (3.33Wh) Li-ion cell replaces the internal battery in the Mini Keyboard RT-MWK08 compact Bluetooth keyboard. The RT-MWK08 pairs wirelessly with smartphones and tablets, and this replacement restores the charge capacity lost in degraded or failed original cells. Dimensions are 53.00 x 34.00 x 4.80mm — measure your existing cell before fitting.

• RT-MWK08 fitment: The RT-MWK08 uses a single-cell flat pack with a specific footprint. The SL-1102A matches the physical envelope and connector orientation so the keyboard's charge circuit sees the correct cell topology without modification.
• Bench tested on actual hardware: We cycled this cell through the RT-MWK08's charge circuit and confirmed the BMS accepted the charge without triggering cutoff. Discharge behaviour stayed within spec across Bluetooth active-pairing and idle standby states.
• Fuel gauge recalibration after swap: After fitting the SL-1102A, run one complete discharge down to auto-shutoff and then charge fully without interruption. The keyboard's fuel gauge IC needs one full cycle to map the new cell's discharge curve — skipping this causes erratic percentage readings from the paired device.

Why the RT-MWK08 shows wrong battery percentage on the paired device after a cell swap

The RT-MWK08 reports battery level to the host device over Bluetooth using a value calculated by the onboard fuel gauge IC. That IC was calibrated against the original cell's discharge curve. A new cell has a slightly different internal resistance profile, so the coulomb counter reads high or low until it re-anchors. One full discharge-to-shutoff followed by an uninterrupted charge to 100% resets the reference points. After that cycle, reported percentages track the actual cell state accurately.

RT-MWK08 not powering on after the battery sat discharged in storage

Li-ion cells that drop below approximately 2.5V trigger a BMS lockout to prevent damage from deep discharge. If the RT-MWK08 was stored unused for months, the cell may have self-discharged past this threshold and the BMS will block normal charging. Connect the keyboard to a USB power source and leave it for 15–20 minutes — some charge controllers include a trickle pre-charge mode that slowly brings the cell back above the 2.5V floor before switching to standard CC/CV charging. If the device still shows no sign of life after 30 minutes, the original cell has likely failed below recovery voltage and the SL-1102A replacement is the correct next step.