Based on your description, it sounds like the alternator is bad. You said the voltage drops when you rev the engine. It should do the opposite.
Also, the idea that you get a click and then it starts normally leads me to believe there is either a loose connection or the starter is going bad.
Lets start simple. I need you to check a couple things. First, make sure the battery terminals on the new battery are clean and tight. Here is a link to help:
Next, I need you to check the alternator output. Here is a link that explains how to do it.
Let me know what you find. Also, at a low idle, it isn't uncommon for the lights to dim and blower to slow a bit.
I will watch for your reply.
Take care and God Bless,
Friday, February 12th, 2021 AT 4:25 PM