Trailer left connected maintains Rivian's 12V battery?

[Dark-Fx]

Left my Rivian connected to the camper while it was sitting at home for two days unused and unplugged from the EVSE. I don't usually do this because I need to reposition the truck to plug it into the EVSE.

Typically I lose 1% of the Rivian HV battery every day unplugged (Gear guard is always on too), but it had not lost any in that 48 hour period. I noticed that it looked like my camper was maintaining the 12V battery in the Rivian, because there was an unusually high DC draw for it. Only thing running was the fridge, which typically is about half the power displayed.

Drove the camper to the storage lot this morning around the time of the dip below 0W. After that the peak usage has dropped and stayed lower. Has anyone else observed this behavior? I'm really quite curious now if backfeeding power through the trailer hitch connection could greatly reduce phantom drain from the HV pack never needing to be activated. I'm considering putting a shunt in line to actually capture what's going on here.

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[COdogman]

That is very interesting

 

[RivianCivilian]

weird

 

[PappaBolt]

It doesn’t surprise me. Not unlike putting a battery maintainer on the 12v circuit via a “cigarette” lighter. Or in this case via the jumper leads.

 

[Marchin_MTB]

Left my Rivian connected to the camper while it was sitting at home for two days unused and unplugged from the EVSE. I don't usually do this because I need to reposition the truck to plug it into the EVSE.

Typically I lose 1% of the Rivian HV battery every day unplugged (Gear guard is always on too), but it had not lost any in that 48 hour period. I noticed that it looked like my camper was maintaining the 12V battery in the Rivian, because there was an unusually high DC draw for it. Only thing running was the fridge, which typically is about half the power displayed.

Drove the camper to the storage lot this morning around the time of the dip below 0W. After that the peak usage has dropped and stayed lower. Has anyone else observed this behavior? I'm really quite curious now if backfeeding power through the trailer hitch connection could greatly reduce phantom drain from the HV pack never needing to be activated. I'm considering putting a shunt in line to actually capture what's going on here.

That is interesting. Haven’t been connected to our camper while parked long enough to notice anything. Also, our camper has no way of displaying load information.

Could this work the other way? If the camper batt voltage is low, would the Rivian charge it via that hitch connection?

 

[Dark-Fx]

That is interesting. Haven’t been connected to our camper while parked long enough to notice anything. Also, our camper has no way of displaying load information.

Could this work the other way? If the camper batt voltage is low, would the Rivian charge it via that hitch connection?

I believe it will but it might be conditional on the vehicle being awake/on to prevent draining it out. I too usually don't leave the trailer plugged in while parked. Will have to experiment with it a bit.

 

[jeeden]

There is a precedent....

 

[IGR]

According to this thread Rivian seem to disable 7pin connector: https://www.rivianforums.com/forum/...o-trailer-lib-while-driving.26202/post-517693

 

[shrink]

Interesting.

When I leave my R1S in Kona, it seems to lose a little less than 1% per day. It’s parked in my garage and plugged in. Most recently it sat for a month. I left it 66% SOC and then set the charge limit to 50%. I think it took about 3 weeks to get down to 50%. I wasn’t following that closely. From what I can tell, it doesn’t charge for days, but then over one 24-hour period I can see charging was off and on throughout the day. I’m guessing it’s topping off the 12V?

I do have a battery tender I could hook up to the 12V as an experiment. Took delivery on this R1S in 7/2023 so I’m guessing it’s a single battery and capacitor? Is it an AGM battery? I’m supposed to specify on my battery charger if it is.

I know this isn’t charging through the hitch connection but could be a worthwhile experiment.

 

[HaveBlue]

Considering a trailer has between 100ah and 400ah, the little 18ah Rivian battery is no match and is a lead acid standard motorcycle/generator battery. There are many replacements for it. Nothing special.

 

[SwampNut]

I would expect the trailer charging connection to be bidirectional just like it is on any other vehicle. It would take a MASSIVE diode to make it unidirectional.

Hey, can you confirm that the trailer disables both the Drive+ and the adaptive? I read that, and couldn't believe that Rivian would be that stupid. Before I build a circuit to fool the truck into thinking there's no trailer, I'd like to verify that this is indeed a problem. Seems so unlikely.

 

[Marchin_MTB]

I would expect the trailer charging connection to be bidirectional just like it is on any other vehicle. It would take a MASSIVE diode to make it unidirectional.

Hey, can you confirm that the trailer disables both the Drive+ and the adaptive? I read that, and couldn't believe that Rivian would be that stupid. Before I build a circuit to fool the truck into thinking there's no trailer, I'd like to verify that this is indeed a problem. Seems so unlikely.

Yes, both HA and adaptive (distance keeping) cc are disabled in town mode. I have a theory as to why that might be and hope it will change (adaptive cc at least) with future software updates.

 

[SPITmadFIRE]

Hey, can you confirm that the trailer disables both the Drive+ and the adaptive? I read that, and couldn't believe that Rivian would be that stupid. Before I build a circuit to fool the truck into thinking there's no trailer, I'd like to verify that this is indeed a problem. Seems so unlikely.

You should make a separate thread about this so everyone can let you know how horrifyingly dangerous that sounds

 

[SwampNut]

You should make a separate thread about this so everyone can let you know how horrifyingly dangerous that sounds

I enjoy idiots telling me how I'm going to die in all sorts of ways, so that sounds fun. Keep in mind that I've owned and driven several vehicles that allow adaptive and/or full ADAS. For example, the Ford does. If I had been warned that Rivian was this stupid, there's a strong chance I would not have bought the truck. This is incredibly stupid of them.

So yes, I will be making a circuit to hide the trailer from the truck. Should be fairly easy and probably $50 in parts, or so. Using inductive sensing and/or opto-isolators. I'll make a new post for it.

I'm also the guy with the steering wheel weight in the Tesla.

 

[IGR]

I would expect the trailer charging connection to be bidirectional just like it is on any other vehicle. It would take a MASSIVE diode to make it unidirectional.

Hey, can you confirm that the trailer disables both the Drive+ and the adaptive? I read that, and couldn't believe that Rivian would be that stupid. Before I build a circuit to fool the truck into thinking there's no trailer, I'd like to verify that this is indeed a problem. Seems so unlikely.

Yes, both HA and adaptive (distance keeping) cc are disabled in town mode. I have a theory as to why that might be and hope it will change (adaptive cc at least) with future software updates.

I have a theory, it's called safety. My Dodge Durango didn't allow adaptive cruise control while in tow mode so I'm not surprised here. Its probably because towing vehicle doesn't know what environmental condition it is in, like fog oh heavy rain, and it wont be able to make proper adjustments to keep its occupants and everyone else on the road safe.

I wouldn't mess with it, but its up to you, just try not to kill anyone lol

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