The Model X has a 7-pin trailer connector, and one of those pins (#4) supplies +12V which, if connected properly, can charge the trailer's battery during travel. In an ICE, this power is supplied by the alternator and vehicle's 12V battery. On the Tesla, I'm assuming it's provided by the 12V battery and that battery's charger from the vehicle battery. This got me thinking. If I'm boondocking/dry camping with a travel trailer, and I have significant energy available in my vehicle battery, but limited availability in my travel trailer, can I just draw off of that pin 4 as needed to charge the travel trailer battery? My research shows that this is done with ICE vehicles from time to time. One important step is to size up the conductor between that pin and the travel trailer's battery to #10 - this limits resistive losses along the length. But it raises a few questions. Is that pin hot when the Tesla is shut down and locked? That is, does it work like an accessory switched outlet would work on an ICE, or is it always on? Will the Tesla lead-acid 12V battery deep cycle too often and become even more likely to be replaced? Does indeed the 12V system get charged even when the Tesla is "off"? I can probably answer the first question with my multimeter here shortly. I am curious about this situation, though, because if one can get a high SOC before finding a nice dispersed/dry camping spot, it could really take away any need for solar or other charging methods while camped. I can't imagine the draw from the trailer would impact the SOC very much on the Tesla, considering the size of most trailer batteries. Mine will have a single 80Ah 12V lead-acid battery, which only supplies 50% before needing to be recharged. That's less than half a kWh. I'd love thoughts on this and explanations why I might be missing something crucial. I recognize limitations in getting to and from dispersed camping sites, and not having a charge available while parked. The question is more about the technical feasibility of this configuration.