About this replacement
Asus ROG STRIX IMPACT II — 3.7V Li-Polymer Replacement Battery (FT802535P)
This 3.7V 700mAh (2.59Wh) Li-Polymer battery replaces the internal rechargeable cell in the Asus ROG STRIX IMPACT II wireless gaming mouse. OEM part number FT802535P. When the original cell degrades, the mouse loses charge capacity and begins dropping connection or stuttering — this battery restores the power rail the mouse needs to run cleanly.
- ROG STRIX IMPACT II fit: The IMPACT II uses a compact Li-Polymer cell at 3.7V with a specific footprint of 38.50 × 24.60 × 8.00mm. The BMS inside the mouse manages charge cutoff and low-voltage protection — the replacement cell must match this voltage and physical envelope exactly or the board won't seat correctly.
- Bench tested on actual hardware: We cycled this cell through the IMPACT II's charge circuit and confirmed the BMS accepted full charge termination without tripping a fault state. Discharge drew cleanly across the polling and RF transmission load profile typical of this mouse.
- Post-swap power cycle: After fitting the new cell, hold the mouse power button off for five seconds before switching it back on. The IMPACT II's firmware reinitialises the battery gauge on a cold start — skipping this step can leave the on-screen charge indicator reading incorrectly for the first few sessions.
Why the ROG STRIX IMPACT II pointer stutters before the battery fully dies
The IMPACT II reduces its wireless polling rate when cell voltage drops below a threshold — typically around 3.4V — to conserve power. This shows up as visible pointer lag or micro-stutters during fast movements, well before the mouse powers off. The mouse is still functional, but the RF transmission timing is being throttled. Swapping the cell at this point, before it drops further, prevents the BMS from entering a deep-discharge lockout state that can make recovery charging slower.
Mouse not reconnecting to USB receiver after battery replacement
A full power loss — which happens during a battery swap — can break the IMPACT II's active pairing state with the USB receiver. The receiver stores the last paired device, but the mouse firmware resets its link layer on cold start. Unplug the USB receiver, wait ten seconds, then plug it back in. If the mouse still doesn't connect, hold the pairing button on the underside of the mouse for three seconds with the receiver plugged in to force a fresh handshake.