Can we limit charge rate at a DC fast charger like not more than 200kw?

[VA99]

Just curious…

just like the state of charge % limitation, if there is a way to limit max rate (for example: not more than 200kw just not to heat up the battery fast and get it throttled then, etc)

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[Donald Stanfield]

The truck’s battery management software takes care of that for you.

 

[Mcdoo]

or, just connect to 150KW instead, but yes trucks BMS will take care of it and it will progressively get better with OTA.

 

[Guy]

or, just connect to 150KW instead, but yes trucks BMS will take care of it and it will progressively get better with OTA.

Well they have had over a year of experience and people still say the thermal throttling happens often so I can see the OPs point about self selecting.

 

[VA99]

Thank you. Yes, user selected rate may be helpful in some situations.

 

[WSea]

Kyle Conner is currently driving to Michigan in his R1T and doing short (extremely short for him) charging updates along the way. Trying a few different things.
Kyle Conner (@itskyleconner) / Twitter

 

[Dark-Fx]

I noticed that the Rivian seems to wait too long to start cooling the pack in reaction to high temperatures in it. If I DC charged regularly I'd probably experiment with flipping the AC on in the truck to start the system cooling before it even gets to the thermal throttling point with the pack.

 

[Riviot]

or, just connect to 150KW instead, but yes trucks BMS will take care of it and it will progressively get better with OTA.

This

After my July/August hot AF road trip with most 350KW EA chargers dead, and seeing Rivian pull 175KW from a 150KW charger, I'm sticking with less is more.

 

[WSea]

I noticed that the Rivian seems to wait too long to start cooling the pack in reaction to high temperatures in it. If I DC charged regularly I'd probably experiment with flipping the AC on in the truck to start the system cooling before it even gets to the thermal throttling point with the pack.

I agree! and the cooling/fan startup is never the same even though in similar conditions. It should come on earlier to anticipate the heating instead of playing catchup with throttled speeds. Yesterday the fan came on after I unplugged.

 

[Cosmacelf]

I agree! and the cooling/fan startup is never the same even though in similar conditions. It should come on earlier to anticipate the heating instead of playing catchup with throttled speeds. Yesterday the fan came on after I unplugged.

That’s insane. The fan should come on when fast charging regardless. Yeah, the software needs to anticipate the cooling load, not react to it when it’s too late. Sounds like a software update is sorely needed.

Here’s Kyle Corner’s latest video where he notices the same thing, which results in thermal throttling (watch first, and then second linked 30 second video)

 

[MoreTrout]

This

After my July/August hot AF road trip with most 350KW EA chargers dead, and seeing Rivian pull 175KW from a 150KW charger, I'm sticking with less is more.

https://www.rivianforums.com/forum/...h-350kw-vs150kw-station-actually-matter.9367/

At least in Branden's testing, for longer charges there was essentially little to no difference between the 150kW or 350 kW.

For those that don't want to sit through the video from that thread or read through the discussion that deteriorated into a bitch session about Youtubers, here are the cliff notes.

He compared 4 charging sessions from 5%-85%. Two were 350kW/500A, one a 150kW/350A and the last a 184kW/400A. Bottom line, all four sessions were just under an hour and the time difference for the entire charge among all 4 was LESS THAN 1 MINUTE.

My takeaway is that the faster initial rates result in much more overheating which then requires increasing throttling for battery cooling to a level below what the lower power charger can maintain throughout the curve, so they catch up.

 

[Cosmacelf]

Here's another theory about what's going on with Rivian fast charging. A lot of these odd results started occurring as winter approached and temperatures got low.

Rivian has an unusual battery pack structure where one layer of cells is at the bottom of the vehicle close to the road. Then there's a shared cooling/heating plate, then above that there's a second layer of cells. In the winter, the bottom cells are going to be very cold, while the top layer, close to the cabin are going to be much warmer. So when fast charging, the bottom layer is not going to want to accept any cooling since it is cold enough already, whereas the top layer will get hot much more quickly, and will require cooling at some point. The two layers, especially in winter, are going to be fighting each other, one layer wanting to be heated up to accept fast charging, while the other will want cooling to accept a fast charge.

Just a thought...

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