Preconditioning - Paying Twice?

[KBabione]

A little background to what prompted this....Starting with 89% battery, we drove our R1S 85 miles to Philadelphia for the day. We changed parking locations twice but still had 52% of our battery left for the 82 mile drive home last night. We put "Home" in as the destination and, thankfully, my wife saw the "Battery Preconditioning" message telling us that the nav system wasn't taking us home but was draining our battery and directing us about 15 miles out of our way to the nearest L3 charger. We stopped nav immediately and put in a closer destination that would direct us back to roads we know. We arrived home safely with 18% SOC. I realized that we could have lowered the destination SOC to 10% and it probably would have taken us directly home (where it still doesn't realize we have a charger), but we're new enough to EV's that we didn't think of that. Anyway, it got me thinking...

What is the real cost and time savings of preconditioning the battery? For example:

• Leave the house with 90%
• At 40% (knowing that there's a L3 charger en route), the Riving starts preconditioning the battery, reducing my percentage from 40% to 20% by the time I get to the charger (it would have been 5% without the preconditioning, so preconditioning cost me 15%)
• At the L3 charger I get back up to 80% - enough to reach my destination

The way I see it, I'm paying for the preconditioning twice: Once at the house when I charged to the initial 90% and again at the L3 charger (to get me from 20% back up to the 35% I would have had without preconditioning). How much time do I really save by preconditioning? I haven't had my Rivian long enough to know! I know other people put an address close to the charger in their Rivian nav system to prevent preconditioning, but that's extra work to get around about the only feature of the nav system that seems to work well. Thoughts?

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[Throwdown]

Ain't no way in hell it needs to use 15% battery to precondition, that's almost 19kwh.

 

[Donald Stanfield]

Your usage number for preconditioning is way off.

 

[KBabione]

Sorry - I don't have actual numbers...It just seems to drain the battery very quickly when it starts preconditioning. Let me restate my questions:

• What is the typical % consumed by preconditioning when it's 50 degrees outside?
• Aren't we paying for that preconditioning twice?

 

[Cycliste]

All I noticed on my road trip was the battery temp went from about 47 C to 25 C before the next charging station

 

[LivingInKaos]

Preconditioning will vary depending on circumstances, but 2-3% would be about normal, 5%+ if you're battery is really cold.

No, you're not paying for it twice. It uses X amount of energy, it's not using it twice, so it only takes 1x charging to recoup it, whether that be on the front or rear.

 

[Tim-in-CA]

All I noticed on my road trip was the battery temp went from about 47 C to 25 C before the next charging station

Where are you seeing battery temp in the UI?

 

[KBabione]

In the new gauges view - Swipe right-to-left on the drive mode screen to bring it up.

 

[LivingInKaos]

Where are you seeing battery temp in the UI?

On the gauges view in the drive mode tab second page, but the battery temp is hidden during charging.

 

[Supratachophobia]

There's also another method, and that's active cooling. I believe that Tesla got rid of "range mode" in later models, but it essentially allowed the HV system rise to a hotter temp; like 100 degrees as opposed to 70 degrees. This required no extra electricity and in fact, as the name implies, saved electricity. Whereas active preconditioning heats the battery up to 120-ish or more I think.

Now maybe things generally run cooler now so organic heating isn't a thing. Or maybe a front axle isn't enough to generate heat. Just some ideas here.

 

[Riviot]

Thoughts?

 

[Craigins]

To each their own. I take about a 20% efficiency hit when the vehicle starts preconditioning. I've seen it start precondition as far out as 60 miles.

60 miles for me is around ~27kWh, or around ~33kWh with preconditioning enabled. It just isn't worth it in my opinion. I've never had my charging speed at a 150kW charger reduced due to the battery being cold (northern IL and WI). Typically the crappy EA chargers are derated anyways so it is just wasting energy by preconditioning.

 

[IGR]

I've been wondering the same thing for a while now and here is what I figured out just now by looking at my recent charge logs:

Method one: Precondition enabled, about an hour drive, outside temperature was 57.
Energy delivered: 70kwh, duration: 28 min

Method two: No preconditioning, 5-10 min driving, outside temperature: 50 (approx.)
Energy delivered 68kwh, duration: 37 min

I only don't remember how much more power it consumed during preconditioning, its hard to quantify. But in my opinion if I can save 10 min at charger, its worth it to me.

 

[R.I.P.]

Charging a warm, happy battery causes less "wear" on it. The engineers at Rivian are trying to protect the battery by getting it to an optimal temperature before forcing huge charges into it.

It is likely you are doing both you and your battery a disservice by trying to defeat the behavior the engineers have programmed into the system.

 

[mtberman]

I am on a road trip in the mountain west right now after traveling for 4 weeks in my 2023 dual motor R1T (0268XX). I have seen the “Preparing Battery” message many times. My experience may not be typical, being a DM.

Mine does preconditioning cooling after I have been either 1. DC fast charging or 2. Level 2 charging for a few hours. Either activity heats the battery up to the mid 90s F and the preconditioning usually cools it down to the mid 70s by the time I arrive at the charger.

I have seen this preconditioning start as far as 140 miles from my destination. It only preconditions in anticipation of a DCFC stop.

When cold, the preconditioning heats the two motors which in turn heats the battery up. This only happened in the AM and not every time. Once it’s warm, the battery never cools down so this warming is a rare, a once per day thing, if that.

Shout out to the Rivian navigation. In addition to doing the preconditioning, it tells you exactly where to stop, how much and how long to charge, etc. and it has been really useful and handy. It has been dead accurate and really builds confidence on the road.

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