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.
The breakers should have a 30 amp rating. In order to diagnose if the dryer is at fault or if it's the breakers/electrical supply circuit is to check the current draw of L1 (Line One) and L2 (Line Two) voltage supply using a clamp on amperage meter while the dryer is running and heating.