Voltage regulator

[Jwhetnall 3]

I was running the 582 today after replacing some fuel system parts.   So the charging system seem not to be working.  Battery voltage @12.38.    Did some wire chasing and found the power wire to voltage regulator was to a constant power post at back of key switch and then to a glass fuse.   My question is  does this unit need to be on a + continuous power supply or can it be to a keyed source?   And the new 15 amp fuse got me 13.58 volts at the battery post.     Regards Joe