R1T Limited Regen Warning: What's normal?

[tcole]

I got my R1T on June 7th, and I live in Tahoe and pretty quickly noticed I was getting the "Regen Limited' warning.

We just took a long weekend to Mammoth Lakes, and the road into town from where we're staying turned out to be a pretty good and consistent regen test.

We are staying at Tamarack Lodge, which is at 8500 feet, and it's about 2.4 miles from the first stop light in Mammoth Lakes at 7,800 feet. Every time we go down the hill, I get the "limited regen" warning near the bottom. This about matches my experience in Tahoe.

It seems I can only do about a 600 - 700 foot vertical drop before the regen warning comes on, and I can see the limited regen indicator.

I got here with a 49% State of Charge and got down to about 29% before I went and charged. Every time we went down the hill I got the warning. So this is NOT an issue of the battery being too full.

I did have a brief conversation with someone at the Rivian service number, but they didn't know if this was normal or not, and we were mostly focused on addressing another issue.

Is this normal? Or should I try to get Rivian service to take a look?

It sure seems pretty annoying. My Volvo C40 certainly doesn't do this.

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[WSea]

Cold soaked battery?

 

[tcole]

Cold soaked battery?

I don't think so.

I went down the hill twice yesterday, the first time was in the morning, and yeah it was coldish then. I think there was some frost overnight. We drove to the Mammoth Mountain main lodge, about 6.8 miles away, down and then up again. So I could see cold being an issue this time.

But then it sat in the sun all afternoon, though temps were probably at most the low to mid 60s. Then we went down the hill again around 5pm, and I'm pretty sure it did the Limited Regen warning that time also.

 

[WSea]

L2 charging just prior? This seems contrarian but during cool weather and charging at home I’d get limited regen coming down our hill which is 140’ drop over about 2 blocks

 

[VNCR1S]

I have the same problem as well. I don’t even get to get more than 1 percent going downhill. I get the limited regen warning which I have not experience with my other ev.

 

[tcole]

L2 charging just prior? This seems contrarian but during cool weather and charging at home I’d get limited regen coming down our hill which is 140’ drop over about 2 blocks

Nope, last charge was at an Electrify America on Friday.

 

[tcole]

I have the same problem as well. I don’t even get to get more than 1 percent going downhill. I get the limited regen warning which I have not experience with my other ev.

Ok, so maybe normal. Thanks for the reply.

 

[usulio]

I get this issue too in the R1S, assumed it's normal, but still a bummer. I was counting on regen to get me farther down I-70 in Colorado but we'll see.

 

[zefram47]

Ok, so maybe normal. Thanks for the reply.

Sadly normal. Seems to depend a little on how hard you're romping on it downhill, but I get it less around 40-50 mph than at higher speeds. Really just depends how many corners require bleeding off speed. Descending Berthoud Pass here in Colorado I was surprised to not get any limited regen warnings, and similarly no warnings coming down into Grand Lake from the top of Trail Ridge Rd in Rocky Mountain National Park. But if I drive up a canyon road and come back down enthusiastically, it doesn't last long before I get limited regen. It does seem like they've improved it a bit and I only seem to lose about half the potential regen where before it was more like 80-90% disappeared.

 

[jjswan33]

It didn’t used to be this way but they did a software update to improve regen and this is what we got. It does depend a lot on the temp of the battery.

The example I would give is near me on Mt Hood. Going from Government camp down to Rhododendron it’s about 3000ft of vertical drop. If I drive it directly after a day of snowboarding I get the regen warning pretty quickly. On the other hand if I am coming over the mountain from the other side and doing the same descent I don’t always get limited regen.

 

[Mathme]

I drove from San Jose to Santa Cruz the last 2 weekends. In about 20 miles, that trip goes over a twisty pass from 0 to about 2000’ elevation and back to 0.

driving to that section of road was about 25 miles on the freeway. Going over last weekend I got no regen warning. Yesterday on the same stretch I got a regen warning. Both times in Sport/high regen.

temps on both days was only in the 60s.

I’ll be curious what Tahoe has in store this weekend

 

[Greg Chick]

I live on a hilltop, whenever I leave my house, it is a 1,000' decline for the first 3 miles. I leave at 85%, the regen limit light comes on at same spot every time. I wanted to harvest the power as I went down so I tried 15 MPH decent, did not work, same battery regen notice. Then I tried the min. speed for cruse control, 25 MPH. Bingo, the regen limit notice did not come on! The 25 MPH was not too fast for the curves and I gained 3 miles as I drove down.
There is one spot where the road is steep, and the road ahead is interpreted by the auto braking function as something to slow for. The truck auto slows to 17 MPH, I do not mind since the curve is sharp. I then reset the speed to 25 MPH and finish the decent!

 

[Electrified Outdoors]

Normal.... probably. Regen can be limited for a number of reasons.

1) high state of charge
2) low ambient temps consistently
3) large amount of Regen (e.g. long down hill or aggressive on/off driving)
4) sustained high ambient temps usually have a higher impact on #3

In your case I don't think high ambient temps are an issue I think it's just normal Regen limitation. 2.4 miles is a long stretch of full Regen.

If your above 85% it will probably come on sooner. If reasonable, only charge to 70% of you want to capture max energy coming down.

 

[Greg Chick]

Yea, it does it even at a 50% charge, so it isn't a high charge limitation. I guess the computer is trying to protect the charger or the battery. But I fooled it! I just do not want to use the brakes! no need when I can re harvest the power spent climbing the hill.
What goes up, must come down, but I may not recover the cost.

 

[Electrified Outdoors]

This is a good article on how Regen works and it's limitations. It's a long read but will help understand the limitations of Regen.

https://chargedevs.com/features/reg...oser-look-at-the-methods-and-limits-of-regen/

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