> The device has to last 5 years on a battery and I didn't want
> to spend time calculating which would be the best solution

As I found out/realised recently, diodes use power. If you
drop the 6V battery voltage by ~15%, that's  ~15% of battery
power wasted. Are you able to get the micro (eg an LF) to
run on just one battery that requires no voltage dropping ?

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