Logitech K810 Illuminated Keyboard Replacement Battery 3.7V 1500mAh

Logitech Illuminated Keyboard K810 — 3.7V Li-Polymer Replacement Battery (533-000114)

This 3.7V, 1500mAh Li-Polymer battery replaces OEM part 533-000114 in the Logitech K810 Bluetooth keyboard. It restores power to the keyboard's wireless connectivity and backlit keys. The K810 is a slim multi-device Bluetooth keyboard, and this cell matches its flat-profile battery bay exactly at 85.00 x 49.80 x 3.90mm.

• K810 platform fit: The K810 uses a single flat Li-Polymer cell rather than replaceable AA or AAA cells. The BMS on the K810 mainboard monitors cell voltage directly, so the replacement cell must match the 3.7V nominal rail — a mismatch here prevents the firmware from reading state-of-charge correctly.
• Bench tested on actual hardware: We ran this cell on the K810 mainboard and confirmed the BMS accepted charge handshake without fault codes. The backlight and Bluetooth radio both initialised normally across all three device-pairing slots.
• Backlight draw management on the K810: The K810 backlight adjusts brightness automatically in low-light conditions, which increases current draw. Keeping backlight at mid-level rather than maximum noticeably extends charge cycles on the replacement cell — the firmware does not throttle this automatically until the cell drops below 3.0V.

Pairing lost after battery swap on the K810

When the K810 loses power completely — as it does during a battery swap — the keyboard's Bluetooth pairing data can drop from memory on some firmware versions. This happens because the pairing table is held in volatile memory backed by the cell voltage. After fitting the new battery, hold the Easy-Switch button for the relevant channel until the LED blinks rapidly, then re-pair from your device's Bluetooth settings. All three device slots may need to be re-paired individually.

K810 shows charging but battery percentage stays stuck

After a full discharge, the K810's battery reporting can freeze at a low percentage even while the USB charge cable is connected. This is a BMS recalibration issue — the fuel gauge loses its reference point when the cell drops below 3.0V. Charge the keyboard uninterrupted for at least two hours without powering it on, then power cycle it fully. The percentage should reset to an accurate reading once the BMS completes one full charge sweep.