Why do Rivians charge so slow?

[jwanderson88]

Recently I've noticed a study done by Edmunds. It rates EV's according to charging speed. The fastest was a Hyundai Ioniq 6 at 868 miles per hour. Rivian R1T was number 37 at 316 miles per hour. That's less than half as fast. That is a significant difference. Why is that? I'd like to point out that the rating number can depend on minor differences that you wouldn't think would affect charging, like tire size. 20- and 21-inch Rivians have separate ratings (37 and 38). If you eliminated these things, the list would be way shorter.

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[COdogman]

Ioniq 5/6 are 800v systems. It’s a nice feature but overall there aren’t that many chargers that can actually support it at that speed. in a few years that will be a different story, but not yet…

 

[jjswan33]

Because in miles/hour the least efficient cars are going to rate the slowest.

I also have an Ioniq 5 and it doesn’t receive much higher power in kW, the technology isn’t much different. The Hyundai is an 800V class vehicle but still only really charges faster because it has a smaller battery. Both vehicles can charge at >200kW.

 

[Electrified Outdoors]

Larger battery and more power hungry truck makes for a slower charge rate when you use miles per hour. If you want to compare apples to apples on charging speed use kw and not miles per hour.

 

[azbill]

Larger battery and more power hungry truck makes for a slower charge rate when you use miles per hour. If you want to compare apples to apples on charging speed use kw and not miles per hour.

From a road tripping standpoint, miles per hour is apples to apples. Time to get to the next charging stop. I actually like the comparison of time to add 100 miles.

 

[jjswan33]

From a road tripping standpoint, miles per hour is apples to apples. Time to get to the next charging stop. I actually like the comparison of time to add 100 miles.

Yep it’s about as relevant as comparing fuel economy between a Prius and an F350. Yes its going to be cheaper to fuel the Prius but the person who bought the truck bought it for a reason (presumably) so most likely would want to compare to vehicles in the same class.

It’s also misleading because miles added by various computers could mean very different things.

 

[sub]

Remember that miles don't come out of the wire, electricity does. A small, efficient, vehicle that goes 2x as far on one unit of electricity will have 2x the MPH charging even with identical battery, charger, ect.

A lower MPH number often just means the vehicle is bigger or less efficient, and Rivian is obviously much bigger than that Hyundai. That is also why the tires impact the numbers you are looking at. Obviously tires don't change how long it takes to fill up the battery, but since it changes how many miles you will go, It will change the MPH number.

Charging rates in MPH is what you care about when you are sitting at a charger waiting. But from a technology point of view it is not the relevant number.

If you're wanting to put a number on charging rates that is more telling about the technology being used and the design/build quality , the number you want is how many minutes it takes to charge from 20% to 80%. (The C rate is an even better metric, but I rarely see any EV charging data using those units. C rate is charging speed in kw divided by battery size in kwh, the number you would want just the average C rate on a 20% to 80% charge)

Rivian isn't doing great there either, but at least when looking at that number, it's a fair comparison vs smaller vehicles.

As far as why Rivian doesn't do great there, it is a combination of things.

Rivian's peak charging rate is limited by its use of a CCS charging port and the 400 volt battery architecture.

A CCS charging cable is limited to 500 amps, so even if the battery could handle more, the charging cable cannot give it more than 500a X 400v = 200 kw.

Tesla's charging cable does not have that 500 amp limit which is why Tesla can exceed 200 kW on their 400 volt system. Some other vehicles get around this by using higher voltages. An 800v system doubles the amount of energy you can push through the CCS connector.

But the peak rate is only part of the story. Rivian can only maintain that peak rate for a few minutes before it starts slowing down. The slow down is caused by several factors, The big ones are overheating, battery chemistry, and willingness to stress the batteries.

The easiest of those to control is overheating. If Rivian improved its ability to cool the battery It could maintain the peak speed longer and charge the battery faster. Other companies may also be willing to stress the battery more, but that could reduce the battery life span so it's not necessarily a bad thing if Rivian is somewhat conservative there.

Although the peak charging rate is the number most talked about, improving how long it can maintain that peak rate has a bigger overall impact. Rivian needs better cooling.

 

[Electrified Outdoors]

From a road tripping standpoint, miles per hour is apples to apples. Time to get to the next charging stop. I actually like the comparison of time to add 100 miles.

Good point, however it's not good to gauge charging speed between vehicles. For that I would expect to see how much energy I can get into the battery within a set period of time. That along with efficiency will tell you how good of a road tripper a car is.

I suppose if you were comparing trucks it may be ok to use miles per hour as an easy way to combine both charging speed and efficiency into one number. It not good when comparing different types of vehicles as it can be misleading.

Battery size, efficiency, and charging speed are all factors I look for. And then I would look at what type of vehicle I want. Obviously a larger truck or SUV is going to be a little bit slower on road trips because it's got a larger battery and it's less efficient. Then you have a car like the Chevy Bolt which is very efficient. However, it's extremely slow on DC fast charging at only 55 kW max. Not many folks charge for an hour. Anyway. The typical charging stop is probably closer to 20 to 30 minutes and you can't just divide the miles per hour in half because of charging curve so it's misleading.

Sorry, thinking out loud again.

 

[jwanderson88]

Edmunds is claiming to have to have created an "industry standard". I'm having a hard time believing that. From what I've learned of charging, the less charge the battery has, the faster it will charge. To make a useful comparison, you'd have to have a uniform starting point, like 20% charge. That's a reasonable level to arrive at a charging station. Then there is the problem that the size of the battery affects how fast it will add 100 miles, or any other number of miles. In short, it looks like Edmunds has failed to create a meaningful industry standard and their test is pretty meaningless. Is an industry standard even possible?

 

[Throwdown]

Ioniq 5/6 are 800v systems. It’s a nice feature but overall there aren’t that many chargers that can actually support it at that speed. in a few years that will be a different story, but not yet…

I think there are a bunch of 800v capable charger, issue is they are mostly EA and rarely work

 

[Riviot]

To answer your Title question, to get to the other side. /s

 

[mikehmb]

Edmunds is claiming to have to have created an "industry standard". I'm having a hard time believing that. From what I've learned of charging, the less charge the battery has, the faster it will charge. To make a useful comparison, you'd have to have a uniform starting point, like 20% charge. That's a reasonable level to arrive at a charging station. Then there is the problem that the size of the battery affects how fast it will add 100 miles, or any other number of miles. In short, it looks like Edmunds has failed to create a meaningful industry standard and their test is pretty meaningless. Is an industry standard even possible?

There are several metrics by which you can rate the speed of charging. I use the most simple, and also because I’m a EE by training, the most technically accurate: charge rate in terms of kW measured over a curve with current SOC. IMO - all other measurements are relatively meaningless since you can radically change the number of miles per kWh based on drive modes, length of drive, starting battery soak temp, and your driving style, especially on the Rivian.

You will see that published here pretty regularly as a comparison point against other vehicles.

Also - relevant:

 

[Polar]

No inclusion of mouse over/alt text? Booooo

Edit - I searched about found it -

Standards - Fortunately, the charging one has been solved now that we've all standardized on mini-USB. Or is it micro-USB? Shit.​

 

[mikehmb]

No inclusion of mouse over/alt text? Booooo

AHH sorry - I’m on my ipad so that’s hard to put in. Here you go …

 

[Throwdown]

I think there are a bunch of 800v capable charger, issue is they are mostly EA and rarely work

Also in my experience if there is a working 350kw a Chevy bolt or an id4 is at it.....

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