Quote:
Originally Posted by Mister B
With my power disconnect turned off, my Magnum was on and registering 13.1V. However nothing showed when I hit the aux battery switch on the master control panel.
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Assume you are talking about when plugged into 120VAC shore power. That would be normal when plugged in as the Magnum is automatically on. Now the challenge is to determine if the batteries are getting charged with disconnect off.
With the original Interstate wiring starting in 2010 you could run the inverter in disconnected mode. You would also get battery charging when plugged into shore power.
Then around 2015 Airstream realized this set-up was draining batteries quicker than desired when in disconnected mode. They came up with SB-164 that added a solenoid to turn off 12VDC power to the Magnum inverter when the batteries were disconnected by the switch. This however had the unintended side effect of draining the batteries even faster when batteries were connected since it took more power to connect the solenoid. It also prevented Magnum battery charging when in disconnected mode.
Then with 2017 models Airstream dropped the SB-164 solution and added a second disconnect switch for the 12VDC going to the Magnum inverter/charger.
With either SB-164 or the second disconnect switch for Magnum inverter/charger when the disconnect switch near the sliding door is turned to disconnect mode the charger function of the Magnum inverter/charger will not charge the coach batteries since the 12VDC line from Magnum to batteries is disconnected.
As Pahaska suggested you can determine if you have either SB-164 solenoid or the second disconnect switch by trying to use the Magnum inverter function with battery disconnect switch in disconnect mode and of course not plugged into shore power. If you have either solution I listed above the Magnum display will be blank since no 12VDC is provided to the Magnum unit.