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 same voltage as traditional disposable alkaline batteries, which are commonly used in various devices such as remote controls, flashlights, and small electronic devices. However, please note that battery technology is continuously evolving, and there may have been advancements or changes since then. It's always a good idea to check with the latest sources or manufacturers for the most up-to-date information on flexible zinc-carbon batteries.