I have a simple alcohol filled one that I bought from Wal-Mart for under $5. Know why? Because the stupid battery was ALWAYS dead when I needed the battery powered one. Guaranteed. Sure it takes 2-3 minutes to get a reading, but it's never wrong and will still be working 100+ years from now, long after the batteries have died and the manufacturer stopped supporting the fancy smartphone app for that $50-100 digital thermometer (which sell for $5-10 at CVS without all the "app" crap).