I have been using Energizer 312 batteries from Sam’s Club. I notice my aids are just slightly louder after replacing the batteries. Today I found a manual for the battery that shows the discharge curve.
On that curve, the voltage is just under 1.4 volts at the start, then after about 5% discharge, the voltage is just under 1.3 volts until over 90%. So I think I hear just slightly louder at first just after replacement, then I don’t notice it.
I can’t post links, but here is an incomplete link:
data.energizer dotcom /PDFs/zincair_appman.pdf
I read that manual more and learned something I did not know: It says to wait 30 seconds after removing the tab before using.
Here is a paragraph for the manual:
The key to miniature zinc air battery shelf life is the tab seal. This seal should not be removed until the battery is put into service. Miniature zinc air batteries stored at room temperature with the tabs left in place and subjected to typical hearing aid service tests show 95% of initial service after one year and 90% after two years. Accelerated testing indicates that room temperature service maintenance at three years should exceed 85%.
To activate air cell battery remove tab. For maximum power, allow the battery to be aired for 30 seconds before placing in device.
The activated (tab off) air cell batteries have an expected fresh capacity maintenance, depending on cell size, of 50% after 3-12 weeks at 20oC (68oF). Beyond 20 weeks, at 20oC (68oF), fresh capacity maintenance drops to 0-10%. It is therefore very important to keep the tab seal in place until usage.