Does your machine have a voltage regulator? If so, check to see if the points inside it are corroded. Clean them with a nail file or some folded emery cloth, then recheck the voltage throughput. If all working properly, you should see something north of 13v at the battery terminals when the engine is above idle.
Maybe someone can provide the specs on the voltage expected, but it should be above the 12v of the battery alone.
Batteries that are more than 4 or 5 years old are always suspects. Especially if stored in off seasons in unheated storage, that seems to shorten their lives. Terminals and ground connections also should be cleaned and reattached just to eliminate that as a problem area. That is a no cost item.
Mark's suggestion of checking the generator output with a multi meter is a very good first step. (If you don't have one, you can get a workable one at Home Depot, they are
useful tools). It is always
better, and a lot cheaper to identify the problem before buying parts.
Not sure what year your 222 is but here is a diagram of the system for the Kohler equipped 222. Maybe it will give you some ideas on tracking down exactly what has failed in the charging system.
View attachment 2578427
Also, here is a link to an MTF charging problem discussion from a while back. Reading through it might give you some ideas and clues.
Good luck and let the forum know how you are making out with the problem.
i have a case 222 with a starter generator its not charging im not sure were to start to test things and also what should the voltage regulator be gaped at? :thanku: