I like your thinking. This will be a great experiment! We’ll see how this works out. If nothing else I should get more use and not be wasteful with the good battery.
I also wear an insulin pump. The battery challenge was easier to determine. The pump manufacturer supplied 2 Energizer AAA batteries. I decided to try Durocell’s once to see how long they would last. The Durocell’s lasted about a two weeks and the Energizer’s last at least a month. So Energizer’s it is. Also when the low battery alert happens on an onsulin pump, you have time to install new batteries. The pump doesn’t immediately shut down like a HA does.