I made up a XT90 “Y” cable to allow solar input (400 watts) through the standard aviation plug but with the option of manually connecting another source feeding the aviation plug input through the “Y” cable. In this case a 3.3kWh backup battery to recharge the AC200 at night when power is low. The AC200 is primarily used to power a 68.7 qt. VL65 dual zone fridge freezer on my boat.
After a few cloudy days of inadequate solar charging, I plug the backup battery into the XT90 plug of the “Y” cable to bring the AC200’s charge up to a minimum to ensure the fridge is powered through the night. Normally the connection is made at night with no solar power input. The voltage of the backup battery provides 48 volts to the AC200.
This has worked fine for me, but I am not seeing any discussion of this particular configuration. Is their a downside to this configuration and are there protections I should put in place, like a solar on/off switch
in the “off” position when connecting the backup battery to the “Y” cable. Thanks!