Charging rates (vs Tesla)

[Nimar]

Trying to understand the reason for the difference in charging rates between the R1S and the Model Y. When you’re at home, both home chargers are 11.5 kW but the Rivian quotes 25miles/charged hour and the Tesla gets 44miles/charged hour.

What’s the reason for the difference? Can Rivian catch up with a software update or some hardware limitation?

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[emoore]

Because the Tesla is more efficient.

 

[teddyang]

Rivian needs more energy to go the same distances as the Tesla (i think it's about double so that 25 vs 44 mil range for the same energy is about right. Also the Rivian battery pack is almost double that of a Tesla 135 kwh vs 77 kwh(i think) so it takes longer to get the same percent gain in charge too.

 

[Nimar]

Interesting. So if the battery is twice the size in the Rivian, is it half as efficient in using the energy (different vehicle weight, etc). Because talking about how many miles you get after one Hour of charging (battery size shouldn’t affect this)

 

[jjswan33]

Interesting. So if the battery is twice the size in the Rivian, is it half as efficient in using the energy (different vehicle weight, etc). Because talking about how many miles you get after one Hour of charging (battery size shouldn’t affect this)

A model Y gets something like 3.8 mi/kWh and a R1S (depending on tires) gets around 2.2 mi/kWh

So using them numbers 11.5kW for 1 hour gives you (3.8 mi/kWh * 11.5 kWh) or 44 miles for the Model Y. While for the Rivian (2.2 mi/kWh * 11.5 kWh) or 25 miles.

The battery size is only relevant in weight but mostly the difference is in the aerodynamics of the vehicle.

 

[SANZC02]

Interesting. So if the battery is twice the size in the Rivian, is it half as efficient in using the energy (different vehicle weight, etc). Because talking about how many miles you get after one Hour of charging (battery size shouldn’t affect this)

It does effect that and that is the answer.

You are charging at around 11 kWh and hour if you are using a 48 amp level 2 charger. If you are getting 4 miles per kWh in the Tesla that is 44 miles, the Rivian gets around 2.2 miles per kWh so you are only getting 24.2 miles for the same 11 kWh.

 

[electruck4x4]

Think of 11.5 kW like 11 gallons of gas. The truck will get fewer miles per watt than a Tesla will, hence why it appears to charge slower.

 

[teddyang]

Interesting. So if the battery is twice the size in the Rivian, is it half as efficient in using the energy (different vehicle weight, etc). Because talking about how many miles you get after one Hour of charging (battery size shouldn’t affect this)

i know, but that's why double the battery size half the efficiency but you get similar range.

I also bring the battery size up because some ppl may wonder why charging 10-80 percent on a tesla is faster then 10-80 percent on a Rivian (taking all the complexities of charge curves out of the equation and just based off of battery size) takes longer too.

 

[silkyjohnson]

A 40 gallon gas tank takes longer to fill than 15 gallon gas tank

 

[CharonPDX]

Interesting. So if the battery is twice the size in the Rivian, is it half as efficient in using the energy (different vehicle weight, etc). Because talking about how many miles you get after one Hour of charging (battery size shouldn’t affect this)

You have it sort of backwards.

Because the Rivian is a larger, heavier, less aerodynamic vehicle, it is less efficient, and needs a battery that is nearly twice as large as the Tesla to go the same distance.

Much as how a Ford Expedition needs a fuel tank that is twice as large (or more) as a Honda Civic to go the same distance.

So you're adding the same amount of "fuel", but only able to go half as far on it. Since you're "adding fuel" at the same rate, the distance added per hour of adding fuel is less. It takes longer to fill the bigger "tank".

If you drove the Rivian 100 miles and the Tesla 50 miles, they would take about the same time to recharge on the same power charger.

 

[Nimar]

Thanks all for the explanation. Helps a lot.

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