Be careful using “Prepare for fast charging”

[SoCal Rob]

We’re in the high desert, the exterior temp says 101° and the battery shows 100°.

I used the new Energy screen “Prepare for fast charging” button to lower the battery temp on the way to charge. I got a little chuckle at a minor coding error when the screen showed “Warming battery for faster charging” since obviously that can’t be what it’s doing.

A couple minutes went by and I checked and this is no status message error: IT HEATED THE BATTERY TO 105°! So I went back to the energy screen, canceled that, and used navigation to route to a charger. When I went to check in the Energy screen I saw something which made more sense: Cooling battery for faster charging.

I don’t know if this is a one-off, so please keep an eye on things if you’re using this and post with your experiences using the new feature. I’ll be providing feedback to Rivian directly about this.

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[mikehmb]

 

[SoCal Rob]

Funny because it’s true.

 

[Wefty]

What temperature do we want the battery for charging?

 

[COdogman]

 

[SoCal Rob]

What temperature do we want the battery for charging?

I think 75°F is the ideal (top or 12 o’clock position) on the battery temp gauge. I don’t think that pre-conditioning actually targets that but maybe tries to get within a range of it. I know our Gen1 would get down to the 80s.
Edit:typo

 

[SeaGeo]

We’re in the high desert, the exterior temp says 101° and the battery shows 100°.

I used the new Energy screen “Prepare for fast charging” button to lower the battery temp on the way to charge. I got a little chuckle at a minor coding error when the screen showed “Warming battery for faster charging” since obviously that can’t be what it’s doing.

A couple minutes went by and I checked and this is no status message error: IT HEATED THE BATTERY TO 105°! So I went back to the energy screen, canceled that, and used navigation to route to a charger. When I went to check in the Energy screen I saw something which made more sense: Cooling battery for faster charging.

I don’t know if this is a one-off, so please keep an eye on things if you’re using this and post with your experiences using the new feature. I’ll be providing feedback to Rivian directly about this.

It will cool the pack. I've seen mine do that. Probably a minor bug in the logic.

 

[Budman]

What temperature do we want the battery for charging?

I've seen it go to 80 to 90F most of the time for optimal fast charging. 100F isn't that much higher.

 

[SoCal Rob]

It will cool the pack. I've seen mine do that. Probably a minor bug in the logic.

Apparently it will heat the pack rather than cool it when manually activated, but cool the pack when a recognized charger is entered as a destination.

While that may be a minor coding error which is easy to fix, the effect on the charging session duration can be very annoying for people on a trip. Also, just how high would it heat the pack? It didn’t stop at 105° so it could be the logic flaw would just keep heating the battery until the manual pre-conditioning timed out.

 

[SoCal Rob]

I've seen it go to 80 to 90F most of the time for optimal fast charging. 100F isn't that much higher.

Right, and going from 100° to 105° wasn’t a huge increase but 100% of the energy used to do it was wasted and it made the charging session last that much longer because I started at 100°, it heated to 105° before I stopped it and it only cooled to 103° by the time I arrived at the charger.

Literally and figuratively: Not cool!

 

[mikehmb]

I genuinely have deep distrust of the system.

Rivian, if you're reading - please just give us a "target temperature" readout on the dash so we know what to expect. Also, publish the optimal battery temps for DCFC as well as for range upon departure.

 

[DuoRivians]

I think I rather leave this alone and let the car handle it. It’s been rare that the car hasn’t heated up the battery—often the issue is that it happens too soon.

 

[Kidentist]

Perhaps this is a feature best used in cold winter days???

 

[SoCal Rob]

I think I rather leave this alone and let the car handle it. It’s been rare that the car hasn’t heated up the battery—often the issue is that it happens too soon.

In hot weather the battery needs to be cooler rather than warmed and letting the car handle it isn’t always an option. Some of us use chargers which aren’t recognized as changers by the Rivian navigation and don’t trigger the automatic preconditioning.

 

[SoCal Rob]

Perhaps this is a feature best used in cold winter days???

I think it’s safe to say that the expectation was that it would do the same thing as the automatic pre-conditioning: cool or heat the battery to optimize charging time. Tapping on the button doesn’t say anything about heating only and, even if it did, then it shouldn’t blindly heat the battery regardless of what the battery temperature is. This is clearly a bug, which is why I wanted to warn people about it and why I reported it to Rivian via the app.

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