I removed the Inverter switch to the battery bank. I had the switch and a ANL fuse with Holder about 8 inches from the switch. I just made a new 4/0 cable it only added about 5 inches to the run.
During the test the Microwave shut down. I'm pretty sure it was at 12 or just under. I will check the manual and see what it says. I'm going to try the test again after removing the switch.
As far as the batteries go I think I am going to live with them this year and next spring I will replace all four with 6 volts. I will have to stay lead acid can't afford the more high tech batteries. 6 volts will take me from 340ah to 4440ah. That will be a pretty good improvement.
Speaking of cost.. My $1000 system had grown to $1900. My biggest mistake was buying a KIT. A kit is fine if you put it where they designed for it to go. They give you X amount of wire for panel to Charge Controller. If your run is longer as mine was you have to buy new and heavier cable. Also the cable provided for Charge Controller to batteries was only 3 feet that is way unrealistic. Again I had to upgrade to longer heavier cable.
I also had to buy several special tools. A large cable cutter to for a nice clean cut on the 4/0 cable. A crimper able to crimp 4/0. MC4 connectors and special MC4 crimper plus a Multimeter that measures more than 10 DC amps.
All in all I have learned allot. I think I am going to like it when I'm Dry Camping in Wyoming this summer.
Thanks for all the help.