I am considering buying one of these for a road trip I am planning this Winter: https://www.amazon.com/gp/product/B07LF6P8D3 It looks like it draws around 20 amps. I assume that would come from the Tesla's 12V battery. Will that be a problem? I am unclear on how the Tesla 12V battery is charged. Is it charged while driving, or only when the main battery is charging? I have seen references to the 12V battery being "deep cycled" which indicates to me that it is only charged when it is pretty much depleted. It would be a real bummer if using such a kettle resulted in a dead 12V battery!
My reading of the Model 3 manual states the 12 volt port is rated at max of 16 Amps so using the port would not be a good idea (this may be related to the gauge of the wires). It does look like the pot does draw about 21 amps when drawing 250 watts. Also the port is only active when the screen is illuminated. Usually the main traction battery has a special DC to DC charger for keeping the 12 volt battery charged. It works intermittently by my guess. I tried something similar to this on a Ford C-Max Energy. I made a direct connection to the 12 V battery (large gauge wires) however and I had to keep the vehicle in accessory mode (radio works etc) to keep the battery being charged from the larger traction battery. Tesla however is VERY good at spotting unexpected current drains and this approach would likely not work but I have not tested it. Some device not using more than 10 A would be a better bet IMO.
Good thought on reading the manual. I had not thought to check that. For the Model X, the manual states it can handle up to 33amps. I hope that means it would be okay, as long as the high voltage battery can keep the 12V charged. For my plan, it only be active while driving would be fine. I would start it up about 30 minutes before the next stop and then transfer the tea to my Yeti style tumbler.
Not going to get hot if it draws 20A, the car will shut it down. And 20A on a lighter plug is pretty much well beyond the capacity of anything.
Right. I read the wrong specification from the manual. The socket is only cable of 15A. A lot more expensive, but this (or something like it) is probably a safer option: https://www.amazon.com/YETI-Rambler-Vacuum-Insulated-Stainless/dp/B07CRGWDSZ
How about something like this. It is 15A and looks like it fits in the cupholder. If you keep it hot, then you avoid the frequent large draw and it probably runs at minimal power. https://www.amazon.com/Spardar-Insulated-Stainless-Automatic-Cigarette/dp/B06XVR831N/ref=sr_1_3?keywords=water+warmer+12v&qid=1569685798&s=home-garden&sr=1-3