Using the auxiliary pin in the 7-pin tow connection to provider 12 volt power to a small trailer

[TheHuskyOrionGoesElectric]

Hey all,

I tow a small homemade trailer and use a ecoflow 800 wt solar battery to power a cooler, lights and water pump. I have solar panels to recharge the system when off grid as well as a 110 input to charge at home or with the Rivian R1T 110 outlets. I was thinking I could use the auxiliary pin on the 7 pin trailer connection to run the trailer if the onboard trailer battery was dead, IE pass through the 12 volt and bypass my trailer battery.

My concern is would that drain the Rivian 12 volt batteries or are they maintained by the main batteries even when parked? How much power would that supply, the same as the standard 12 volt outlets? I have been searching the forums about the subject without luck so far.

I know I can make a 12 volt cable to do the same thing and use the 12 volt outlets in the truck but it would be much simpler to just have it pass through the wiring harness.

The plan is to eventually have a fully electric camp kitchen in the trailer that can use both 12 volt and 110. Though it does look like for cooking I’ll need the 110 with my budget.

Any thoughts, insights appreciated
Eric

Sponsored

 

[HaveBlue]

A Bargmann supplies a maximum of 30A. It will do this while the truck is running. A typical RV battery stores 100Ah at 12V or 200Ah at 6V which is roughly 1Kwh. The Rivian joke of a battery is likely 30Ah at best with very little reserve capacity. The HV pack constantly has to recharge it which is why The Rivian has so much Vampire drain that it can only make it 3 hours standby while parked before the 12V wakes the car back up.

 

[WSea]

As others have mentioned on the forum, it’s best to power off truck and use your ecoflow. If it Needs more charge use the trucks 120 receptacle for an hour or so and then turn 120 receptacle off.

 

[LongJoSilver]

I'm also interested in tapping into this power for lighting and other camp things without keeping the AC inverter powered on via camp settings.

One experiment I've considered running is just powering something off the 12v batteries in my driveway to just see what happens. Does it fully drain? Does the HV battery replenish it? I just haven't done it because of lack of time and fear of killing the 12v-- but at home should be minimal risk. I would like to think if the voltage gets to some value like 11v it would notice and charge up. If you have the time, maybe you can run with this and take one for the team?

One thought I have on the connection point is that the trailer connection might power down when the truck sleeps or lights are off. You might need to tap into something that is directly connected to the battery if you don't want it to time out. You could probably figure this out with a multimeter while the truck is sleeping.

 

[mindstormsguy]

I have an Aerovault trailer that has its own battery for interior lights and a winch. It’s wired from the manufacturer directly to the 7 pin connector as well, so it will charge from the tow vehicle.

I’ve been using this trailer with the Rivian for a while, and haven’t had any problems. The Rivian will use the HV battery to keep the 12V system topped off even if the Rivian is “off”.

I actually have a GPS in my trailer too, and I can monitor the 12V system voltage using telemetry from the GPS. It’s actually quite interesting. The rate of battery discharge with the trailer disconnected is pretty low (it’d probably last 1-2 months without being charged). But with the Rivian plugged into the trailer, the 12V voltage decreases 2-4x as fast (so the trailer battery is actually supplementing the Rivian 12V system). But I can see the HV system be used to top off the 12V periodically to keep things charged.

 

[mindstormsguy]

Here’s a capture of the battery voltage.

On the left region is where the trailer was connected to the Rivian, but parked. You can see the spikes while charging, and a pretty steep slope discharging between charges. Then on the vast majority of the plot, you can see what the trailer battery discharge looks like without the Rivian connected.

 

[katisaun]

A Bargmann supplies a maximum of 30A. It will do this while the truck is running. A typical RV battery stores 100Ah at 12V or 200Ah at 6V which is roughly 1Kwh. The Rivian joke of a battery is likely 30Ah at best with very little reserve capacity. The HV pack constantly has to recharge it which is why The Rivian has so much Vampire drain that it can only make it 3 hours standby while parked before the 12V wakes the car back up.

What's a Bargmann?

 

[HaveBlue]

The 7 pin trailer receptacle

Sponsored