Pushed the limit too far today towing long distance

[Dark Helmet]

Had to throw the white flag today about 2/3 of the way home from a family vacation. 6.5hr/418 mile one way.

tl;dr: heat soaked battery couldn’t get me home.

Ambient temps were in the mid 90’s all day, and I was 2 DC charger stops in before things started to get a little odd. First issue was with some fussy charging initiation but as usual I blamed the network. Later on during a charge session I watched the charge rate tank from about 150 to under 1. Throttle was limited, and the pack was showing 136 degrees.

After about 10 minutes of sitting off the charger it cooled about 5 degrees and let me continue with normal throttle range, but I kept accel light and maintained a 55-60 mph interstate speed. It went as low as 120 at one brief point, but otherwise hovered between 132-136. There was nothing I could do that seemed to help reduce the pack temps. Had a very friendly Rivian roadside service rep on the phone at one point, though the solution was basically to let it sit until the numbers were closer to 125-130.

After 12 hours of driving I was tired of nursing it along and figured it needed an overnight to cool down. Safer to rest than drive fatigued from problem solving.

The truck pulled wonderfully on the way to our vacation spot. The extra 2 or 3 degrees must have been just enough to stress the thermal management. Weather otherwise was very pleasant. Sunny and very little wind. Had no problems maintaining between .9 to 1.2 mi/kwH pulling that aero nightmare.

I share all this with you for general awareness of Gen2 dual motor large pack performance in higher heat scenarios. The truck’s estimated towing weight was 3500 lbs. Even with some margin of error I think I’m well within the towing capacity. Curious if any of my fellow towers out there are seeing thermal issues like this in our hotter summer days?

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[2kwik4u]

What were the ambient temps where you were towing?!? Just curious as a data point.

What did you do to resolve? Grab a hotel and extend the trip by a day?

I tow with a G1 dual large, but haven't fought any thermal issues yet. Also haven't strayed for enough from home to need multiple charges while towing.

That's not a heavy load, but is certainly very poor from an aero perspective. Good friend and I both had 5.3L GM trucks, and went on vacation to TN with them a few years ago both towing boats. Same weight between his 26ft tritoon and my 20ft fiberglass. He got 8-9mpg and I got 12-13mpg. Roughly the same weight, but his was like a big parachute back there!

 

[Dark Helmet]

On the trip down, ambient temps ranged from 67-90 degrees. Coming back home, we started at 80 and drove most of the trip between 90-94 degrees. So definitely hot, but not like southwestern US hot.

And yes, got a hotel for the night. Ambient temp dropped to 75, battery was 109 degrees indicated when I got in the truck. Currently taking a charge just fine at the nearby DC charger. This particular ChargePoint charger peaks at ~85 kw and the truck maintained that to about 75% SoC, and it’s starting to reduce normally as I get higher in the SoC. So hopefully today I can finish this journey.

 

[2kwik4u]

On the trip down, ambient temps ranged from 67-90 degrees. Coming back home, we started at 80 and drove most of the trip between 90-94 degrees. So definitely hot, but not like southwestern US hot.

Gotcha. Doesn't sound like absurdly bad towing conditions.

What kind of efficiency were you getting?

Was the A/C keeping up in the cabin or did you turn that off to help the battery?

 

[electruck]

This sounds like a problem with the truck that Rivian needs to investigate.

 

[JacobAZ]

Although I was not towing, just drove back to Arizona from California along I-8. The ambient temperature at El Centro was 116. Battery temp was about 110. The cabin was comfortable with temp set to 75. We preconditioned to charge in Yuma. Yuma ambient temp was about 110 degrees. The battery cooled a little down to 107 for charging. Charging in Yuma went normal. The next day driving from Phoenix up to Payson on 87 we passed a half dozen ICE vehicles pulled over with their hoods up. Ambient temperature 108 - 100. The R1T had no issue. Although I don't tow, I have been very happy with the R1T battery temperature management and cabin air. At these temperatures it looks like it uses about 8% of the energy to keep things cool driving highway speeds.

 

[Smeek]

i don't tow anything, so this might be really naive, but is it typical to block so many chargers when you are charging while towing something? can you unhook it to charge?

 

[flybone89]

I tow a 6,000 pound Airstream with a Gen1 Max pack - and readily admit the Airstream is definitely more aerodynamic so it’s hard to compare. But since getting the trailer last August I have not had any overheating problems similar to yours. That includes 90+ temps and high humidity on trips around Ohio and Kentucky.

Efficiency has averaged a solid 1.2 with a 1.35 to Columbus this week to camp for the holiday - my best so far! When I head home tomorrow it will be 90 and I am expecting a headwind so will keep an eye on it and let you know if I see the kind of temps you saw but I don’t anticipate it.

Kevin

 

[DCFC]

That pontoon boat is about the equivalent of towing a parachute. Aside from that, I'd check to see how dirty the radiators are. Depending on where you live, they could be caked up in bugs.

 

[Captblue]

I just completed a 800 miles round trip in the south 90-94f towing a airstream with no issues. Gen1 quad truck large pack. Looks like a service appointment to me.

 

[Dark Helmet]

Yeah the A/C was doing great. Efficiency was also normal for that boat, about .9 to 1. Something else that I remembered about yesterday was that I didn’t remember hearing the front cooling fan running. When it’s really cookin’ it is loud, but I didn’t hear that. Maybe the fan had a temporary problem?

I did end up making it home today with no issues. Temps stayed down, all was normal.

@Smeek the unit I was blocking in that pic wasn’t working. If I can’t safely keep my trailer somewhere out of the way I’ll unhook it. Takes me all of 30 seconds. This charger was in the back corner of Buc-ee’s and there were several other stalls open in front. If I ever find myself in a weird position I’ll leave a note on my dash with my number in case someone needs me to move. I love my EV friends and don’t want to be a nuisance!

 

[MountainBikeDude]

Yeah the A/C was doing great. Efficiency was also normal for that boat, about .9 to 1. Something else that I remembered about yesterday was that I didn’t remember hearing the front cooling fan running. When it’s really cookin’ it is loud, but I didn’t hear that. Maybe the fan had a temporary problem?

I did end up making it home today with no issues. Temps stayed down, all was normal.

@Smeek the unit I was blocking in that pic wasn’t working. If I can’t safely keep my trailer somewhere out of the way I’ll unhook it. Takes me all of 30 seconds. This charger was in the back corner of Buc-ee’s and there were several other stalls open in front. If I ever find myself in a weird position I’ll leave a note on my dash with my number in case someone needs me to move. I love my EV friends and don’t want to be a nuisance!

Full disclosure, have never towed with my Rivian, but have seen how it handles hot weather and road trips, and have also seen nearly every out of spec video on the subject.

The unfortunate engineering quirk of a Rivian, is it's not the best at both cooling the battery and maintaining cabin temps on more strenuous drives, like towing, and repeated DCFC sessions. Truch drives for around 2 hours at high amp output, the rocks up to a DCFC charges aggressively for 45-70 minutes only to run the gauntlet again.

Best thing you can do is turn off the cabin HVAC, and let the vehicle focus on charging and maintaining battery temps. This diverts all the cooling capabilities directly to the battery.

Until Rivian steps up it's battery cooling strategy, and potentially dumps in a second AC compressor (like the lightning) then I feel like these summer misadventures are going to become more the norm.

 

[Dark Helmet]

Full disclosure, have never towed with my Rivian, but have seen how it handles hot weather and road trips, and have also seen nearly every out of spec video on the subject.

The unfortunate engineering quirk of a Rivian, is it's not the best at both cooling the battery and maintaining cabin temps on more strenuous drives, like towing, and repeated DCFC sessions. Truch drives for around 2 hours at high amp output, the rocks up to a DCFC charges aggressively for 45-70 minutes only to run the gauntlet again.

Best thing you can do is turn off the cabin HVAC, and let the vehicle focus on charging and maintaining battery temps. This diverts all the cooling capabilities directly to the battery.

Until Rivian steps up it's battery cooling strategy, and potentially dumps in a second AC compressor (like the lightning) then I feel like these summer misadventures are going to become more the norm.

Given the ambient temps that would make sense, though we did park on an off-ramp, turned off the hvac and let it sleep (to see if doing zero work would cool the battery) and it didn’t drop the temp at all. Your point still stands though, sounds like there’s room for improvement!

 

[MountainBikeDude]

Given the ambient temps that would make sense, though we did park on an off-ramp, turned off the hvac and let it sleep (to see if doing zero work would cool the battery) and it didn’t drop the temp at all. Your point still stands though, sounds like there’s room for improvement!

Yeah, parking and sitting is just going to make the truck think it's done working, and can just passively allow the thermal mass that is the battery pack, to just cool gradually as heat dissipates. A better approach might have been to hit the manual precondition button, and hang out? Honestly, its all just drawing straws on that front.

 

[Dark Helmet]

Yeah, parking and sitting is just going to make the truck think it's done working, and can just passively allow the thermal mass that is the battery pack, to just cool gradually as heat dissipates. A better approach might have been to hit the manual precondition button, and hang out? Honestly, its all just drawing straws on that front.

We actually did try the manual precondition option and it wouldn’t allow it. I can’t recall the exact message it gave us but it was not going to let it happen. As you mentioned this though I do wonder if the camp mode would have done anything different. Hope I never have to find out, but in the event it happens again maybe I’ll try that!

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