Why is alternator slow to charge battery?

[Amphibiographer]

Yesterday I started the engine after securing the postive cable from the starter to the battery in a better position. This is all I did but there was no whine audible when engine was in low idle. I could not get out of the harbour to test the engine in gear under load so I will do that tomorrow. Also will take photos of the installed new alternator.

[amizerin]

I recommend to check the orange wire with voltmeter. Recently, I had a similar issue with the alternator not charging batteries at all. I purchased a brand new alternator and it did not help. Then I started checking the orange wire going from the alternator output to ammeter. When engine not running it showed only 2V while it was supposed to show about 12.5V. I disconnected the old orange wire completely and ran a brand new 8 gauge wire from the alternator to ammeter positive. Now it's charging just fine.