amp meter needle is crazy

When i notice that problem I was going back home with kids and wife didn't took time to verify the voltage that going out the alternator or going in the battery

Will try tomorrow if time let me do it
going for a ride and will bring multi meter and few wrench

The guy. I bought it from told me it could be a regulator problem
He told me to be sure its the alternator the problem I should disconnect it
When it does the problem if the light stay at the same intensity and gage stay calm
In the discharge zone that will be it...��