Well designed As noted on https://git.lekensteyn.nl/ltunify/tree/registers.txt, the "07" register shows the battery status. If you want to learn more about the technical side, you can read my article about reverse engineering the protocol. SOURCE: mouse dead and wont charge. is there a battery to change? When opting for rechargeable batteries, choose high-quality rechargeable AA or AAA batteries with sufficient capacity (mAh) to ensure extended usage between charges. It's essential to recharge them regularly to maintain consistent mouse performance and prevent unexpected battery depletion. Many users find rechargeable batteries to be a convenient and eco-friendly choice for powering their Logitech ergonomic mice, offering the same reliable performance as disposable batteries while being more sustainable in the long term.