Sulz said:
You had any issues?
From what I have now read it seems its to prevent sparking which could ignite gasses .
But Ctek doesnt do this anyway.
I would recommend trying to find a way to keep the Ctek unit outside the car not in the 'frunk' as you will not know if it is ok or not, or if it is overheating which they don't ( often do ....)
Maybe fab up some type of frame to keep it off the ground, its rated for outside anyway so can in theory stand an outdoor winter Insulation class: IP65
Ambient temperature: -20°C to +50°C, output power is reduced automatically at high temperatures
( I have had mine outside over winter on my RR sport , admittedly improvised with a large flowerpot over the charger and yards of 3m self amalgamating tape though)
Under Frunk method:
Buy a comfort connecter that connects to the battery using eyelets
http://www.vertar.com/ctek/CTEK-battery-charge-indicator-wire-attachment/
You can cut at one point with snips and make it suitable to squeeze under the terminal once you slacken the terminal bolt. Fit both + & - to the batter terminals like this and leave it forever. Connect your Ctek comfort lead male to the female ( stop sniggering you lot !)
You can buy a 'Ctek comfort extension lead' and run into the ' Frunk' leave lid on mechanical latch, not fully closed.
http://www.vertar.com/ctek/CTEK-battery-charger-conditioner-extension-lead/
Locate Ctek outside in safe place or in a suitable enclosure under/near ' the car. Switch on to ' Car ' mode....check after a short while that battery anf charge function is still ok.
Alternative set up is still with Ctek unit outside the car and use the extension lead and the 12v socket connection, you can close the door fully ( gently) on the lead as the seals do not compress the Ctek extension lead , check by pulling slightly once the door is closed....
The sparking comment is only relevant if you use the croc clips onto the terminals but if you do ever use these, its always advisable to switch off the Ctek prior to disconnect the clips anyway.
Modern batteries, and certainly the AGM type, do not gas off like the old type Lead acid batteries did ...