New Member with charging issue

VR is grounded, Checked with resistance test.
With key on:
from ground on bat to each VR terminal I get same as battery 12.5.
W/blue disconnected from alt., green at VR reads 4.6V.
Checking with sperry DM4100A multi meter.

No luck testing for amperage.

With grn terminal at alt grounded with key on:
12.5 at Bat.
11.2 blue at alt.
Also have large spark when connecting Bat. ground to green on alt with key on.