Thanks for all the replies. I have done some more problem determination. Based on the input I have received so far I think the data shows my big problem is at the battery isolator where there is about a 1.5 volt drop. Then each of the switches seem to lose between 0.1 and 0.3 volts, then further down the line it is fairly consistent throughout the rest of the circuits.
I wasn’t able to get inside the battery charger
to figure out its starting voltage, but I measured the voltages across the other elements the same as with the alternator.
My course of action will be to disassemble and clean all battery connections between the isolator, switches and batteries, then re-measure what we have. While I am doing this I will also measure any drop across the switches & depending on time might dismantle and clean them as well.
Any other recommendations would be appreciated …. Thx
Here’s the data
Alternator Batt Charger
Voltage out of Alternator 14.21
Voltage at Starting Battery 12.98 13.98
Voltage at House Battery 12.85 13.39
Voltage at Garmin
Battery Isolator middle -- directly from Alternator 14.28 13.03
Batt Isolator Top -- to Starter Batt 13.12 -
Batt Isolator Bot -- to House Batteries 12.94 13.30
Battery Switch 1 (Starter) Top 13.22 13.90
Battery Switch 1 (Starter) Bot 13.10 13.95
Battery Switch 2 (House) Top 12.95 13.36
Battery Switch 2 (House) Bot+A16 12.90 13.37
425 Amp inline Fuse In 12.95
425 Amp inline Fuse Out 12.95
At 70amp DC Circuit Breaker in Panel In 12.98 13.18
At 70amp DC Circuit Breaker in Panel Out 12.98
Volts at largest Red Wire coming into Panel 13.00 13.39