You should definitely get a battery that is about 1.3v for the big wall clocks. The much larger hands take loads of Power so a much better battery will very last extended. Lithium batteries are reported to last a long time in clocks. Please begin to see the video https://embroidery-hoop-stand-in66543.iyublog.com/37379760/a-review-of-hand-embroidery-home-decor-clock