is 2fa supposed to send codes every 15 seconds?
not particularly exceptional android smartphone with aegis authenticator from f-droid installed to 2fa.
I authenticated and logged in but my device kept receiving codes every 15 seconds 'till I stopped aegis.
Is this normal? Seems like a waste of battery.
your device is not receiving codes. Your device is generating them and the point of doing it so rapidly is to make stuffing attacks unviable. The generation of codes is almost nothing for your battery.
If you have issues with your battery Android has the Battery Usage tool in the settings menu to see what apps are consuming power. The age of a battery also matters. more than 3 years the battery will wear out. You could look at replacing the battery if it is a couple years old.
BTW, it's not receiving anything. It's calculating locally, which has a minimal impact on battery. Turning on the screen to check the codes will likely use more already.
This is normal, the codes are calculated based on time. It should have a infinitesimal impact on battery.
By default, according to the RFC 6238 standard, they are generated every 30 seconds. But this time step can manually set to faster intervals. However faster as 30 seconds is not very user friendly. RFC 6238