OK, I understand. Your original post led me to think that you wanted to power the unit on the controller side of the panels, not the battery side. Now I understand that you have some old controllers that flow both ways.
This type of controller that allows battery voltage on the solar side of it is a poor choice, since this would allow the panels to drain the battery at night unless external diodes were installed. These external diodes would cause a voltage drop during charging that the panels would have to overcome, which would be difficult because they are pulled to battery voltage by design of the controller.
In other words, purposefully using an old, inefficient solar/wind regulator that could add to battery drain just to power a new tech radar would be a questionable choice. Why not just use an efficient controller and power the radar directly from the battery?
Mark