What happens if you disable HV + 12V battery and close everything?

[Dolemite]

Of course it works lol. That’s how it was designed. Even the manual states this.

The thing is the manual is not always right and doesn't always apply to every version. It's still helpful to test things to verify.

And the question was whether it will still work with the high-voltage battery disconnected, considering it appears there's some amount of "intelligence" in place to recognize a charged vs. discharged 12V battery.

 

[android04]

Good to know for sure that it works, but I didn't doubt. When the car is asleep or the 12v battery is dead, the HV battery is disconnected from everything by the contractors. That's pretty much the same as unplugging the harness under the rear seat. But in case anybody is ever unsure or doubts, we can link them right to this thread so they can see that Dolemite tested it and it worked.

 

[smatthew]

And the question was whether it will still work with the high-voltage battery disconnected, considering it appears there's some amount of "intelligence" in place to recognize a charged vs. discharged 12V battery.

It's been a while since I stared at the circuit board for vcfront but I seem to recall seeing the parts needed for an aux power supply and watchdog - all Tesla would need to perform/validate a "dead 12V, but 9V present at terminals" situation

 

[BlkM3]

Does anyone know what happens if you disconnect the 12V battery, disable the high voltage battery, and shut the doors & hood? Does this mean you're SOL? I haven't managed to do this (yet).

Not sure how the dead 12V + auxiliary frunk opening "works." I know you can only open the frunk when 12V is dead, but must there be secondary power from HV for the car to "know" this? Also, not sure if "dead" = "gone" - would the frunk open if it's just... not there?

So many interesting new ways to screw yourself over with this car.

I cannot open the frunk with 12 volt power source if the battery in the frunk is disconnected. Basically I tried to change the battery, disabled HV, removed the old battery, put the new battery but did not connect the wires to new battery and accidentally closed the frunk. I did not receive pencil post to SAE adaptor along with Ohmmu battery. I tried to open frunk connecting 9V, 12V to front bumper wires, enabling and disabling HV did not work. Called Tesla CS, they said I have to tow vehicle, I scheduled mobile appointment for tomorrow.

 

[brkaus]

Contact ohmu? Maybe they have more experience with that situation?

 

[puckpurnell]

OHMMU is a terrific company and they'll give you excellent service advice.

 

[android04]

I cannot open the frunk with 12 volt power source if the battery in the frunk is disconnected. Basically I tried to change the battery, disabled HV, removed the old battery, put the new battery but did not connect the wires to new battery and accidentally closed the frunk. I did not receive pencil post to SAE adaptor along with Ohmmu battery. I tried to open frunk connecting 9V, 12V to front bumper wires, enabling and disabling HV did not work. Called Tesla CS, they said I have to tow vehicle, I scheduled mobile appointment for tomorrow.

I've read a few reports of 9V not working anymore to jump open the frunk, but 12V still working. You may be in a more unique scenario that causes your car to not pop open the the frunk, but what are you using as the 12V source to power the wires behind the tow hook cover? If you are using a jump starter or battery charger, they probably don't output anything unless they detect at least a weak voltage from a 12V battery (so they would never work to jump the frunk because those two wires don't go to the 12v battery). That is part of the "reverse polarity protection" that most jump starters and battery chargers have nowadays. If that's what you are using, instead try to find some sort of battery or wall wart that outputs 12v instead. You could even line up 8 AA or AAA batteries and use that, but that could be tricky.