Days in Inventory. The formula to calculate days in inventory is the number of days in the period divided by the inventory turnover ratio. This formula is used to determine how quickly a company is converting their inventory into sales.
How long do hearing aid batteries typically last? A standard hearing aid battery lasts anywhere from 3 to 22 days, depending on the hearing aid type, battery type and capacity, and the amount of hearing aid use. How do I know if I should change batteries? Change your batteries if sounds become distorted or you have to turn up the volume more than usual.
In theory, it should be easy to estimate the expected battery life of the hearing aid. Given that a size 312 battery has a capacity of 145 milli-Amp-hours (mAh), one merely divides 145 mAh by 1.3 mA to arrive at an estimated battery life of 111.5 hours.