Thanks for all the replies so far
To clarify a couple of things that may not be clear in order to help the collective:
House and Starter batteries are sealed Lead Acid (L/A)
Thruster batteries (2 in parallel) are Optima Blue Top AGM
Alternator supply is split in 3 by a Sterling ProSplitR (PSR), zero volt splitter (rated to 180amps). This replaced the twin diode splitter system originally installed which was failing (giving high volt alarms on the engine
control system). Alternator senses the House battery via the PSR.
House battery is monitored using a Nasa Battery Monitor
. Normal charging
voltage under engine is 14.4V to 14.5V. Checked and confirmed by multimeter. This is also seen at the Starter. I do need to verify the voltage seen at the Thruster (plan to install a voltmeter at some point).
I therefore agree that I may be worrying about nothing as the voltage at the AGM could be a couple of tenths of a Volt lower. As it turns out Optima themselves state the following charge voltages:
Alternator: 13.65 to 15.0 volts
Battery Charger: 13.8 to 15.0 volts; 10 amps maximum; 6-12 hours approximate
Float Charge: 13.2 to 13.8 volts; 1 amp maximum; (indefinite time at lower voltages)
Given this data perhaps there is nothing to worry about a 14.4V supply
Cheers and cold beers