As of my last knowledge update in September 2021, flexible zinc-carbon batteries typically have a voltage rating of around 1.5 volts. This is the standard voltage output for most disposable batteries commonly used in household devices like remote controls, toys, and small electronic gadgets. However, battery technology is an evolving field, and there may have been developments or new products released since then. I recommend checking with up-to-date sources or manufacturers for the most current information on flexible zinc-carbon battery voltage ratings.