It's very easy to swap out the batteries. I hit the battery disconnect button. I open the box containing the exhausted batteries and remove the wing nuts holding the wires to the posts.
I lift out the dead or tired battery and stick in the other one. Spin the wing nuts, pull the battery disconnect button, and it's done. Takes me about 90 seconds. I could have a switch do the job -- that would be more elegant than my current setup, which is pretty primitive.
The other advantage of having a spare battery is that when we park the trailer in the shade (which is often), I can take the depleted spare into a nearby patch of sunshine with my portable solar panel. We often do exactly that.
And this little snafu with my batteries reinforces my desire to have "one and a spare." If the two batteries were always together, and one dies catastrophically, the remaining good battery would be quickly drained.
I'm a very risk-averse person. Belt and suspenders. ;)
