Hi I have and old wheel horse and it has a fin like unit mounted to the firewall, I see it is called a Rectifier / Regulator, can anyone tell me what this does and when it or if fails how do I test it and what are the symptoms?

Thanks

this unit changes a/c to d/c testing depends on the engine and each manufacture has specific proceedure kohler briggs onan the biggest symtom of a malfunction in the charging system is a battery that is not getting a charge good luck