High Charging Rate. Found Voltage Drop Need Guidance Please

Mattax said

There is one variable not mentioned so far, but Kit's caution about the battery reminded me.
When the engine was running and the voltage fluctuating, did you notice what was the ammeter showing?
If the battery is drawing a lot of current, that will increase voltage drops on the feed lines.

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@Mattax

My ammeter is no longer accurate. I am running crackedback's "wire around" to take some of the load off the bulkhead. Installing that wire is why I then installed a voltmeter and crapped when I saw the high voltage. Likely not a new development yet the battery is 10 years old and seems fine? Gotta leave the car now to go out. I'll do the tests both you and KitCarson have recommended tomorrow and advise. Really appreciate your guidance.