External wiring

[Drmouse]

Hi all

I go camping fairly regularly. In every car I've had previously, I've added an external connector to supply 12v (and sometimes 240v using an inverter) for running lights etc in my tent.

However, I'm struggling a bit with doing so on a Model 3. I'm considering connecting to the 12v under the rear seat (carefully, with good fuses and circuit breakers), adding a 12v connection in the boot, then wiring that up to an inverter (with protection) and bringing both 12v and 240v to connectors outside the car. However, I can't seem to find a decent way to route the cabling for it.

Anyone have any ideas on the simplest way to bring the wiring out of the boot?

 

[Watts_Up]

@Drmouse I would be very skeptical making any change or splicing to any Tesla wires,
especially if you are still under warranty !!!

Those wires are very thin and aluminium type.​

​

Better would be finding an identical male and female connector​

to build an easy to insert or remove homemade junction harness.​

Instead of accessing the 12 V directly under the rear seat I would recommend:

1. You could access inside the car to an always on 12V line,​

even when the car is in slip mode, using the OBD2 connector.​

​

There are specially made ODB2 harness available for the Model 3,​

depending of your model year.​

​

Search TMC threads talking about the 'Scan My Tesla' Bluetooth App.​

​

2. Why not adding a fused line directly to the 12 V battery?​

​

The bolts clamping the battery terminal are long enough,​

that you can add an additional Stake Eye terminal and nut​

without the need and risk to disconnect the 12V battery terminal.​

​

I would recommend at the same occasion to plug on top of the​

battery a Bluetooth 12 V monitor to check the battery voltage.​

​

​

About the 240 V, I would be very careful using it for camping.

I would recommend keeping the inverter and the device connected​

to it inside the car, as I assume that you would like to recharge a laptop.​

​

Why not in this case using a DC-DC Step Up Voltage Converter (12 V to 18 V)​

instead of a DC-AC (12 V to 240 V) and AC-DC (240 V to 18 V) inverters?​

​

Try avoiding the risk to have a 240 V wire running on the ground​

and the plug possibly exposed to moist and people or kids​

walking on top of it.​

​

If you really need to have a 240 V inside a tent, I would​

recommend using a GFCI outlet with the ground wire​

plugged if possible to a grounding rod.​

​

Note: Please use upper case for units like V, A, W...
as they are used to honor the inventor.

​

​

 

[Drmouse]

So, what I have done in the past with ICE cars is connect to the battery or fuse box, with an appropriate fuse in place.

Connecting to the battery on a Tesla isn't a good idea for anything but very small loads due to the tiny size of the battery, whereas on an ICE vehicle it's fine to draw tens of Amps for a fair amount of time. I've quite happily run a 1kW load from a car battery terminal before: You have to be careful not to drain the battery, and be very careful with the wiring used, fuses etc, but it's doable. You couldn't do that with a connection to the Tesla battery.

I'm not aware of a connection point other than under the seat which would allow such a load to be drawn. I'd be open to suggestions of anywhere else.

As for running mains, I generally get a mains connection from the site where possible. We have suitable, suitably-protected wiring to do so. However, these are not always available, which is why I used to have an inverter in the car. I always used it with the correct protection: Fused with thick cables on the 12V side, RCD and breaker on the mains side in the car, and the same cabling used for site-provided EHU.

The other possibility I've considered is adding an auxiliary 12V battery in the Tesla. However, this would still need me to be able to run the cabling out of the car somehow, and would still need a way to charge it at a decent rate (if the ICE battery started running low, I could always just start the engine and it would both provide the power needed and charge the battery). Plus, that adds significant additional cost and weight.