R2 10-80% charge test (by State Of Charge)

[Proxy]

How about an “800”v vs “400”v real world comparison with a very efficient RWD fast charging sedan vs an inefficient slow charging AWD pickup? Same 640 miles in one day trip in very similar conditions mostly on Hwy 101 SoCal to far north NorCal. Keep in mind Hwy 101 is windy and has lower speed limits once it is not a freeway. Ioniq 6 SE with 18” wheels and efficient tires had two stops. One at 25 minutes and one at 23 minutes. R1T quad with 21” wheels and efficient tires had three stops. One at 25 minutes, one at 14 and one at 41 minutes. Yes, I had to ration my liquid intake. So 48 minutes charging and 12 hours vs 80 minutes charging and a 12.5 hour day. Significant? You decide.

The 400 is in quotes because the Rivian tops out close to 450 volts. Edit: 800 volts in quotes since the Ioniq 6 tops out close to 700 volts.

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[mkhuffman]

How about an 800v vs “400”v real world comparison with a very efficient RWD fast charging sedan vs an inefficient slow charging AWD pickup? Same 640 miles in one day trip in very similar conditions mostly on Hwy 101 SoCal to far north NorCal. Keep in mind Hwy 101 is windy and has lower speed limits once it is not a freeway. Ioniq 6 SE with 18” wheels and efficient tires had two stops. One at 25 minutes and one at 23 minutes. R1T quad with 21” wheels and efficient tires had three stops. One at 25 minutes, one at 14 and one at 41 minutes. Yes, I had to ration my liquid intake. So 48 minutes charging and 12 hours vs 80 minutes charging and a 12.5 hour day. Significant? You decide.

The 400 is in quotes because the Rivian is between 400 and 500 volts.

I bet you could have dropped that second charge if you spent 40 minutes at the first one. Personally I prefer longer, less frequent stops.

Trip time may have been a little shorter since you would not have the time need to exit, find the charger, and then get back on the road. Maybe save 5 minutes?

 

[macb00kemdanno]

“Let him cook!”

 

[Jeremy3292]

I don’t plan on ever using a CCS1 adapter personally, even though I own one from Tesla. Plenty of native NACS options. Adapters should be a thing of the past.

 

[junglebird]

I don’t plan on ever using a CCS1 adapter personally, even though I own one from Tesla. Plenty of native NACS options. Adapters should be a thing of the past.

Until you're out in the boonies of Colorado or Wyoming where it's mostly CCS, or Tesla v2 that are Tesla-only. It's improving but probably at least a few years before a non-Tesla can go adapterless out here.

 

[Jeremy3292]

Until you're out in the boonies of Colorado or Wyoming where it's mostly CCS, or Tesla v2 that are Tesla-only. It's improving but probably at least a few years before a non-Tesla can go adapterless out here.

East coast bias of course here

 

[fxo]

Is an 800 volt architecture better? The most widespread DC fast charger is the Tesla version 3 Supercharger. Charging an 800 volt car typically only can reach 150 kW at a version 3 Supercharger while the 400 volt Rivian R2 reaches 230 kw. On an Electrify America fast charger an 800 volt car can charge much faster although these chargers often have issues that lower the charging speed or fail to charge at all. So while 800 volt architectures can charge faster in theory in practice they often charge slower. There are version 4 Tesla Superchargers and other newer DC fast chargers that will support the full charging speed of 800 volt architecture.

https://www.bozy.com/2025-hyundai-ioniq-5-charging-vs-tesla-supercharger/

You hit on the correct analysis here. The reason companies such as Hyundai and BMW have moved to 800V here is the truly difficult part of the game here. Battery longevity, the state of the thermal management system, issues with safe enough adapters if you want to use CCS based charging points.

It all reeks of a compromise at Rivian, not to mention long term *(hidden costs) of owning the Rivian. Rivian pads its ridiculous salaries for its MIT class executives, but gives the customer 400V which is not "better" ... go ask an EE what you would want to throttle Volts over Amps.

Melting class 1 adapters is not my idea of a great first row experience from a "luxury brand". God help you if you burn your house down for some reason.

<<from AI>>
So what is safer for battery thermal management and overall long term health of the battery system to add kw's using amperage or voltage?



For a given amount of power, adding it through voltage (higher volts, lower amps) is the gentler path for both thermal management and long-term battery health. The reason is one of the cleanest relationships in the whole system, and as an EE you'll recognize it instantly:
Power is P = V × I, but heat is I²R.

 

[mkhuffman]

You hit on the correct analysis here. The reason companies such as Hyundai and BMW have moved to 800V here is the truly difficult part of the game here. Battery longevity, the state of the thermal management system, issues with safe enough adapters if you want to use CCS based charging points.

It all reeks of a compromise at Rivian, not to mention long term *(hidden costs) of owning the Rivian. Rivian pads its ridiculous salaries for its MIT class executives, but gives the customer 400V which is not "better" ... go ask an EE what you would want to throttle Volts over Amps.

Melting class 1 adapters is not my idea of a great first row experience from a "luxury brand". God help you if you burn your house down for some reason.

<<from AI>>
So what is safer for battery thermal management and overall long term health of the battery system to add kw's using amperage or voltage?



For a given amount of power, adding it through voltage (higher volts, lower amps) is the gentler path for both thermal management and long-term battery health. The reason is one of the cleanest relationships in the whole system, and as an EE you'll recognize it instantly:
Power is P = V × I, but heat is I²R.

As a EE, you should know that a typical NMC cell in a pack is 4.2V when fully charged. A LFP cell is typically 3.6V fully charged. The stress on the cells are not any different based on how they are arranged, if you charge each cell at the same rate. Right?

The "V" in your formula is max 4.2 V (or 3.6 V), not 400 or 800.

You might need a new AI.

 

[fxo]

As a EE, you should know that a typical NMC cell in a pack is 4.2V when fully charged. A LFP cell is typically 3.6V fully charged. The stress on the cells are not any different based on how they are arranged, if you charge each cell at the same rate. Right?

The "V" in your formula is max 4.2 V (or 3.6 V), not 400 or 800.

You might need a new AI.

Alone your statement is true, however...

there are other factors to stress, not sure which factor is most "stressful" on battery cells, but one clear one is temperature. Temperatures will be different in the middle of the pack, than on the outside (door frame) for example. Temperature stresses the NMC family of batteries in different ways and differently across architectures. Hence the cryptic but necessary charging curve that we see. And the crux of the battery EV is how well the entire architecture is balanced>

NMC* family of batteries and how they take stress over LFP:
high state of charge - more stressful on NMC
high voltage - more damaging...
high temperatures in varying places along the pack architecture - more sensitive
faster charging - generally more stressful
and so on...

Rivian did what they had to do. Doesn't mean you have to like it, or consider them world class at anything. A solid mid-fielder. That's striving to stay alive.

 

[mkhuffman]

Alone your statement is true, however...

there are other factors to stress, not sure which factor is most "stressful" on battery cells, but one clear one is temperature. Temperatures will be different in the middle of the pack, than on the outside (door frame) for example. Temperature stresses the NMC family of batteries in different ways and differently across architectures. Hence the cryptic but necessary charging curve that we see. And the crux of the battery EV is how well the entire architecture is balanced>

NMC* family of batteries and how they take stress over LFP:
high state of charge - more stressful on NMC
high voltage - more damaging...
high temperatures in varying places along the pack architecture - more sensitive
faster charging - generally more stressful
and so on...

Rivian did what they had to do. Doesn't mean you have to like it, or consider them world class at anything. A solid mid-fielder. That's striving to stay alive.

It seems like you are moving the goal posts.

Of course properly heating and cooling the battery pack makes a difference in battery stress. But there is no reason why you can't properly cool a 400V pack. The cells are not under more stress just because it is a 400V pack, as you originally claimed.

There are drawbacks to using 800V, which have been discussed in this thread already. IMO the best reason to have 800V is to reduce stress on the charging equipment, making it easier for the infrastructure to deliver the power needed to quickly charge the pack.

There is no indication the pack is not properly cooled when charging at 650 Amps.

 

[fxo]

the pack that runs hotter is the one that costs you.

With a melted Class A adapter one can only imagine how hot those cells and the pack overall gets.

Too funny, Mr Rivian really knows how to melt down their clientele don't they...

 

[DuoRivians]

It seems like you are moving the goal posts.

Of course properly heating and cooling the battery pack makes a difference in battery stress. But there is no reason why you can't properly cool a 400V pack. The cells are not under more stress just because it is a 400V pack, as you originally claimed.

There are drawbacks to using 800V, which have been discussed in this thread already. IMO the best reason to have 800V is to reduce stress on the charging equipment, making it easier for the infrastructure to deliver the power needed to quickly charge the pack.

There is no indication the pack is not properly cooled when charging at 650 Amps.

The battery pack is a lot more than just the cells. The copper or aluminum connections between all the cells make up a lot of heat too. If the heat can be dissipated easily, then Rivian should have done so from day one, and so should every EV battery pack manufacturer. But there is a limit based on 400V and all the rest of the components that make up a battery pack.

All else equal, 800V gives you all upside. The downside is the financial cost. Personally, I’m never going to pay for another EV that costs more than $50K and has 400V. Why pay for mediocre tech? The rest of the world is accelerating, and if the US won’t catch up, I don’t want to pay for that.

 

[Jeremy3292]

the pack that runs hotter is the one that costs you.

With a melted Class A adapter one can only imagine how hot those cells and the pack overall gets.

Too funny, Mr Rivian really knows how to melt down their clientele don't they...

Do you think 800v battery packs don’t get to 50-55C? You think the 400kW they’re pulling is “chilly” bc of 800v architecture? Nah man they all get hot, proper cooling is needed at all times, 800v just allows you to charge faster not cooler.

 

[sparked]

Melting class 1 adapters is not my idea of a great first row experience from a "luxury brand". God help you if you burn your house down for some reason.

Did you even follow the circumstances where this person purposefully didn't use the readily available NACS cable? Why would your house burn down at a DC fast charger?

 

[KineticKev]

I feel like this thread isn't what I expected.... Came here looking for a few people to say how fast/slow their 10-80% charge was with R2. Maybe how long it stayed at a higher KW/state of charge, etc.

Instead it got very technical. I'm actually a very technical person that loves specifics however I understand that the average person just needs to know what the average baseline of plugging up with a NACS (no adapter) is like. What is generally the best case scenarios and worst case scenarios.

I should have also known it would roll into an 800V vs 400V conversation.

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