please help . voltage drop test on alt and batt.

so i've been doing a lot of research on voltage drop and used on a 09 tahoe and im wondering if anyone can suggest a reason for my findings.

while running and all avalible loads on, i had

14v on alt. pos and neg connections 
14v on battery pos and neg connections
and the part im not understanding is
50v for alt ground(mount) to batt neg.
250v on alt pos to battery pos

adding a 0gage wire between the block and batt. neg lowered the 50v to 15v
(i work in an audio/ remote start shop and this came in for an different issue and was told about what another shop had done and charged him so after i did what he was here for, i did this just out of curiosity thinking i would find normal or non-problematic readings)

where im confused is how im getting such high numbers for - to -  and from + to + 
 

Can you post a pic of your meter?

My best guess is that your meter is auto-scaling.  Are you sure it isn't reading milli-volts, mV?

 

thanks thats most likely the case, im new to asking questions on the interwebs so i did not think to get photos. will keep in mind for next time. thanks again for the response