Strange: Different timekeeping behaviour of 2 WP34S calculators

[burkhard]

(05-22-2019 11:16 AM)rkf Wrote:  "BATT" on this bad behaving WP34S says 2.7V - maybe that's not enough to keep the time? Unfortunately, I don't have the good one with respect to time WP34S at hands for now to check its BATT level.

I think maybe that is the problem. If it says 2.7V under low load, it might drop down further during some extended operation. And maybe that is enough to cause troubles.
My WP34S is likewise reporting 2.7V on BATT as well, but as I key something in, I can see the "low battery" light flashing on... It still has correct time and date (I also have a crystal), but maybe trouble soon?

What does BATT report on the "good" calculator?
Why not try swapping the batteries between them?