Some weird electrical stuff alternator related

[BillBerner]

Yup, me again.
I ran a direct wire from the alternator output to house battery bank b4 launching this season.
Also added a dedicated starting battery.
Batteries are connnected for charging through an Acrs
They are totally isolated from each other normally otherwise.
Noticed 2 weird things today.
When battery monitor at nav station was set to batt 1 (starting) while mororing the monitor read 9 volts. At the battery terminals it was around 12.9. Getting stranger, the tach read 0 rpm's. The acrs said it was under voltage. Voltmeter at engine panel read 12v but I find it's usually about 1 v under
When the battery monitor was off or turned to Batt 2, the house bank, the tach came back to life. Should have checked the acrs to see If anything changed there, but didn't.
So, bunch of questions.
1. What the heck is miswired?
2. Is the alternator actually charging anything. Doesn't look like the starting battery is getting anything through the acrs since it says undervoltage. I'm going to
Check voltage at alternator
Output tmrw.

As a finl piece of the puzzle-I'm also
Seeing low voltage, around 9, at the glow
Plug solenoid with key turned to mentary position. Getting the solenoid to
Work by giving it a light whack while the key is turned.

Some weird electrical mojo going on here.

Thoughts?

The good news is I'm ony first long weekend On the water of the season. May 4, not bad
Thanks

Bill Berner
Hull 66
Spartina
Stamford ct