Low charge to no charge issue pulling hair out

. Is that ok or not ok thats the first change of signal from what battery had
1.5v voltage drop. Is excessive. Even my 0.4 is more than I would like.

Path...

Battery to headlights

From the battery to the starter relay
From relay to fusable link
From fusable link to bulkhead
From bulkhead to main splice
From main splice to ignition switch
From ignition switch to dimmer switch
From dinner switch to bulkhead connectors
From bulkhead connector to headlight bulb ( might be another connector along the way)

Battery to alternator

From the battery to the starter relay
From relay to fusable link
From fusable link to bulkhead
From bulkhead to main splice
From main splice to the ammeter
Through the ammeter
From other side of ammeter to the bulkhead
From the bulkhead to the alternator post.

A quick test would be to get a proper jumper wire and bypass the ammeter.

If the voltage drop goes down you could part or all the problem.