My KS10s are out for repair. To replace the internal, rechargeable batteries before my warranty expires in October…
So, I’m saddled with old tech (ReSound Forte 8) for an out-of-town wedding this weekend. These 2017 ReSound HAs use the 13A battery.
Using the paired ReSound Smart 3D app on my iPhone… Is there anyway to check my remaining battery life realtime?
Or do I just get the 3 Beeps & You’re Screwed™ notification? 
Different model of Resound, but my experience with 4 iterations of Resound and size 13 batteries, it is the 3 beeps and 15 minutes to go. The zinc/air batteries tend to hold maximum voltage to near death. Makes it hard for them to predict.
If they’re your old aids then I guess you know around how long the batteries usually last. If so then change them the morning of the day you expect them to die, or the morning before that to be conservative.
Thanks for the reply! Makes sense.
And what a great role model, the humble zinc-air battery…
Having recently turned 60 years of age, I also aspire to hold maximum voltage to near death! 
Making me likewise hard to predict! 
Thanks for the reply! We made it through the weekend unscathed.
Turned 90 this year, the first 89 are the toughest. 