So I did look into it. The battery they recommend is lithium, normal Duracell are alkali. Optimum are part lithium, part alkali.
However the reason they recommend lithium is the potential for cell leak is higher - nothing to do with the power supply to the system, as it were.
Okay, update:
I have two sets of P1S.
Swapped batteries from good to bad pedal.
Swapped battery cap from good to bad.
Examined cell housing, looks the same.
On the good pedal, and historically on the bad, I see:
PWR-64nnn Connected
In About I see battery “good” or “new”
Calibration succeeds
Power records in Garmin
On the bad pedal;
PWR-64nnn does not connect at all
It can connect to a newly appearing a hex number
HH:hh:hh:hh:hh
In About I see battery “67%”
Calibration fails
No power registers in Garmin
