Many of the people have observed that while operating the Magic Mouse, they face some significant problems. It has been seen that in first generation Magic Mouse, charge lasts for a very short period and Bluetooth connection problems are plenty of the time present. And an issue like not being able to charge the mouse at the time of using it in Magic Mouse 2 is faced. Unfortunately, Bluetooth connection problem is encountered by it too.
Source: Solve Magic Mouse Disconnect Issues on Mac