Yours are new tech. The old ones were "cutting edge" 25 years ago, and absolutely ate batteries. My Federals were one of those. I had a job running glass filled Delrin that absolutely ate up the rack and pinion of indicator calipers, so I bought in to the new digitals at that time. If you got a month out of a set of fairly expensive batteries, you were good. I didn't mind at the time, it was part of the cost of doing business.