Hearing aid batteries should be changed about every 7 to 14 days based on 16 hours per day use cycle.
The exact schedule for changing batteries depends on the amount of time the hearing aids are worn and the power consumed over time.
Most new digital hearing aids have battery warning indicators. Before the battery goes out, the hearing aid will beep to indicate that it needs to be changed.
Batteries are inexpensive, costing often less than 50 pence each. Generally, the smaller the battery size, the shorter the battery life.