Here is how I have gone about installing the battery tender extension on my CanAm Spyder F3T SM6 (2016). I think this should work for any F3s, where-in the battery is located in the front, behind the frunk.
Step 1 is to remove the plastic frunk container. Its held down by 4 plastic plugs. Using a flat head screw-driver, pull up the top part of the plug and then the bottom part and finally take the plug off from the hole.
Then remove the cover as shown above. I slid my fore-finger in the 2 slots shown by the 2 red arrows in the above picture and then slowly pulled the plastic piece up. A center part of the frunk container is held down by this plastic cover marked by the red rectangular area in the above picture.
Frunk container and the cover off, as shown above.
Then ran the battery tender extension cable as shown in the picture below. As my cable is colored black I have outlined it in red color so that the path of the cable is visible in the picture.
There is a fuse on the positive terminal of the cable which is connected to the positive terminal of the battery (red) and the other one to the negative (black) terminal. I detached the negative terminal first and then the positive terminal. Attached the battery tender cable plus the regular cable to the positive terminal first and then did the same at the negative terminal. I was able to string the positive end of the cable through the rubber cover that covers the positive terminal of the battery, so finally its all concealed and safe.
Fished the other end of the cable through the top and let it stay as shown above. Once the plastic cover is put on its snug in place and does not move around.
That’s it. Whenever I had to put the battery tender on, I open the frunk, slight open up the right side of the top plastic cover in order to slide the connector out, connect it and can safely close the frunk back without any issues.