Had an ordinary wall clock with "disappointing" battery life. I could remember that I'd "only just" changed the battery ie within the last year. Measuring the battery gave a reasonable 1.2/1.3 V but the clock wouldn't run, the gears would twiych but not drive. Investigation found corrosion at an internal pressure contact cleaned that up and the clock would run with the same battery and has been running for a good month or three since.