I have had a new narrowboat delivered with a Cyrix CT linking the engine start battery to the bow thruster battery. When the engine is started, the alternator is delivering 14.4V (as normal) but the voltage on the two battery terminals of the Cyrix are typically 13.8V to 13.9V and the two batteries the same voltage (although the bow thruster is down around 0.1V - long wire run to front of boat). In the two weeks we have been off-line only once did the voltage reach 14.0V. Voltage is reported on the Victron BMV712 smart and also checked on my calibrated multimeter. Voltage recorded via my Rasp Pi running the victron software.
Anyone got ideas why the Cyrix is dropping the voltage (or is anything else likely to be dropping it)?