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Constant Unswitched Power on 12V outlet

Pezmc

Nomad
Apr 26, 2016
10
0
London, UK
I'm looking for a way to keep the 12v outlet powered in our TM3, even when the car is parked and/or in deep sleep, while wasting as little power on other functions of the car.

I spend a significant amount of time away from chargers, or mains outlets, wild camping in the countryside, and use my car to charge my laptop and other devices, but right now, the 12v outlet turns off after ~15 minutes of inactivity.

The only workaround I've found so far is to enable sentry mode or camp mode, but that leads to a not insignificant drain on the battery that I'd prefer to avoid given I can only charge infrequently.

I've tried:

- Leaving the door slightly ajar, car still went to deep sleep after ~30 mins
- Searching the forums/reddit for possible fuses that can be jumped or other tricks
- Leaving a weight on the drivers seat and getting out from the passenger door

Are there any tricks to keep it powered either software or hardware (like jumping a fuse)? Or another source of power (capable of 12A continuous) I can wire a cigarette lighter to?

Edit: FWIW I also have a "solar generator" I use, the car is mostly a backup for when there's not much sun and that's running low
 

grmdl3

Member
Apr 21, 2020
154
106
Oregon
Given the small size of the stock 12V battery, and the fact that discharging it to low voltages makes it really hard to get inside, let alone drive away, this seems like a bad idea. How about just putting in a second 12V source somewhere that is independent of the car?
 

RyanT

Member
Sep 9, 2014
388
158
Portland
When I did my trailer lights I wired it directly to the battery. It's not hard to run a line from the front into the trunk of the car.
 

grmdl3

Member
Apr 21, 2020
154
106
Oregon
When I did my trailer lights I wired it directly to the battery. It's not hard to run a line from the front into the trunk of the car.

...but it's a little, itty battery with known issues unless it has been replaced by the user with something more substantial. To me, it's risky to rely on it to do what the OP is asking. Up to you, though.
 

P3dStealth

Member
Nov 12, 2019
932
993
USA
Option 1. Run a wire to the 12v battery and add a plug somewhere to your car. Obviously if you use it a lot it's going to put some wear on the 12v. I ran a 12v for my trunk it's really easy.

Option 2. Buy a 12v portable power station. Lota of them on Amazon but they are far cheaper on aliexpress. They look pretty cool actually I want one now.
 

RyanT

Member
Sep 9, 2014
388
158
Portland
...but it's a little, itty battery with known issues unless it has been replaced by the user with something more substantial. To me, it's risky to rely on it to do what the OP is asking. Up to you, though.
It's my understanding that the penthouse turns on periodically to keep it charged up. I think if it's drained too much the car can throw errors? I'm not completely sure. You would run into the issue with any connection to get a 12v constant though since it would have to come from that battery.
 

RyanT

Member
Sep 9, 2014
388
158
Portland
Option 1. Run a wire to the 12v battery and add a plug somewhere to your car. Obviously if you use it a lot it's going to put some wear on the 12v. I ran a 12v for my trunk it's really easy.

Option 2. Buy a 12v portable power station. Lota of them on Amazon but they are far cheaper on aliexpress. They look pretty cool actually I want one now.

Option 2 doesn't sound bad. You could be more mobile with this solution too. For example take the power station to the tent or whatever. You would just have to remember to plug it in to charge while you're driving.
 

Pezmc

Nomad
Apr 26, 2016
10
0
London, UK
Given the small size of the stock 12V battery, and the fact that discharging it to low voltages makes it really hard to get inside, let alone drive away, this seems like a bad idea.

This is exactly why I want to keep the car awake when charging. If the relay to the high voltage battery is connected, then the 12v battery is supplied from the high voltage battery using a DC/DC converter.

When I did my trailer lights I wired it directly to the battery. It's not hard to run a line from the front into the trunk of the car.

Option 1. Run a wire to the 12v battery and add a plug somewhere to your car. Obviously if you use it a lot it's going to put some wear on the 12v. I ran a 12v for my trunk it's really easy.

If I wire a supply straight to the 12v battery, it's going to drain and not be topped up until the car turns on, assuming the voltage doesn't drop so low that the car won't even wake or unlock. For something that draws a low current like a dashcam or lights this is probably a non issue, but it's not going to work for my use case!

Yeah, I'd just get a big power bank if you want to charge your laptop and other USB devices.

Option 2. Buy a 12v portable power station. Lota of them on Amazon but they are far cheaper on aliexpress. They look pretty cool actually I want one now.

Thank you for the suggestion, I already have one, in fact, that's actually what I'm charging (when not charging my laptop directly) using the car. My 900Wh external battery only lasts a few days.

--------------

Does anyone know of a way to keep the 12v socket powered when the car is "sleeping", but keep the high voltage battery engaged?
 

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