On Sunday at the boat I found the house batteries at 13.58 V and + 10 Amp charging. I ran the engine for 25 minutes and later found the battery bank at 12.8 V and not charging. Where is the high end danger point where we need to be concerned and taking action?
The new charge algorithm of the Magnum inverter/charger is an on-off one. Instead of having a float voltage all the time, the charger comes on and then goes off again until the voltage drops to 12.6 volts. I presume that you came onboard when the algorithm came on and then afterwards it went off. So far there is nothing to worry about.
If you find the charger always on, charging at 13.5 volts that is a problem.