I recently got my first battery "maintainer / charger". It is a CTEK MXS 5.0 and works great so far. But, I wanted to find an easier way to hook it up. I know that there are several ways to make a connection inside the frunk, but I really didn't want to have to open my frunk every time I wanted to hook up the charger. So after doing a little research I found a really cool magnetic connection from a company called MagCode. In addition to being a simple magnetic connection, there is only 12 volt power at the connection point when the magnet is in place. So that means it doesn't need to have a cover because there is no power unless it is connected to the charger. I wanted to find a place at the front of the car that was easy to access and would be easy to return to stock if I ever wanted to. What I decided to do is mount it to one of the blanks that is used for the headlight cleaners. I am very happy with the results. It is very easy to use and if I ever forgot it was connected and pulled away the magnet would just pull loose and wouldn't cause any issues. I have to admit that I was a little concerned that it wold be visible and disrupt the aesthetics of the car, but when you are looking at the car it really isn't noticeable. If you know what to look for you can see it, but 99% of people will never notice it.
Here are a couple of pictures.