Sorry not a very good drawing.
Jan[ Parent ]
That doesn't explain why the controller would show 13.8V while the battery was at 12.6V. Might double check the connections with a volt meter. G-[ Parent ]
I have my doubts about the controller. Not rated for full load of inverter. Connect the inverter directly to the battery. Most inverters will shutdown on low voltage, making the controller redundant. Keep the other loads connected to the controller.
Your wire is thinner than I would use, but its what you have. Lengths are short, making the above changes should allow it to work.
Have fun, Scott.[ Parent ]