Hearing aid batteries last anywhere between five and 14 days depending on the above factors. You will know it's time to replace your hearing aid batteries when the aids start beeping. One solution to save money and make batteries last longer is to purchase rechargeable batteries.
To clarify: you have a main panel with a 60A breaker. That breaker feeds a subpanel which has a 100A main breaker and then some smaller circuit breakers in the sub-panel. If more than 100 coulombs of charge per second flow through the sub-panel main breaker, it will trip and cut power to the subpanel breakers.
A dryer for instance, on the 30 amp breaker, is typically 5000 watts, which is 20.8333 watts, you must oversize the breaker for motors. You can connect more load to your panel than it is rated for, because of diversity (not all are on at once). if you overload it, the main breaker will trip.