Below is a response that I received from Kohler regarding the same question, they also refer to a Joh Deere spec# 27509, where can I find this spec and a wiring diagram?
"So I’ll bet this is a Wide Area Walk Behind (WAWB) mower which has a recoil starter and an electric PTO clutch. In this application, we only use a rectifier, as opposed to a Regulator/rectifier. This uses an Unregulated charging system. It is normal to have a seemingly high amount of voltage in such cases. This is because there isn’t a battery to use as any kind of “power reserve”, so to speak."