I finally tested my Yeti 400 in the truck. Sorry it took so long but I got distracted with motorcycles. :wings:
My Yeti 400 is NOT drawing down the vehicle battery in the way you describe. I tested with a 12v LED light and with the charge port connected the light will not light unless the Yeti 12v socket is turned on. This is of course the way we would expect it to be. Perhaps there is a problem with some of the Yetis.
Do you guys have solar panels to test with? Conventional wisdom says that you should be able to power an LED light with the 12v socket turned off and solar plugged in; just like you are currently doing with the vehicle battery.
I think you should all hit up GZ for a warranty. Getting power from a 12v socket that is supposed to be off is a pretty scary proposition to me.
Best regards,
Matt Crawley