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thrill

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Interesting. From what I’ve read and watched to date, which apparently were the wrong sources if what you’re saying is correct, even 32A would be mostly sufficient. FYI. I’m not looking to fill the vehicle from empty every night. I highly doubt I’d be even 1/3 to half empty 95 percent of the time.

Would you be willing to provide some layman’s terms/examples? This would be my first EV so I’m sure there are some factors I’m excluding. Thanks.
I'm not DucRider (I ride an HP4), but my charging needs are simple enough for my current EV (an i3s, range about 120 miles) that I just plug it into the 110 outlet every night. It takes 2 nights to fill from empty. Daily use is probably 40 miles. When we need to go farther we hit a local DC fast charger for an hour-ish, or take the smog generator (the other BMW). After getting comfortable with EVs you do the slightly more necessary refuel planning without much effort.
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Fenwayfan77

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I'm not DucRider (I ride an HP4), but my charging needs are simple enough for my current EV (an i3s, range about 120 miles) that I just plug it into the 110 outlet every night. It takes 2 nights to fill from empty. Daily use is probably 40 miles. When we need to go farther we hit a local DC fast charger for an hour-ish, or take the smog generator (the other BMW). After getting comfortable with EVs you do the slightly more necessary refuel planning without much effort.
Good to hear some real world scenarios. Thanks. I'm planning to go the Level 2 house route, so I think I'll definitely be fine with the 40A for my particular needs (unless there are some crazy things I'm not contemplating), which are definitely not the same as most. I do use a work vehicle (only for work use) which significantly changes the landscape.
 

ElectricTrucking

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Interesting. From what I’ve read and watched to date, which apparently were the wrong sources if what you’re saying is correct, even 32A would be mostly sufficient. FYI. I’m not looking to fill the vehicle from empty every night. I highly doubt I’d be even 1/3 to half empty 95 percent of the time.

Would you be willing to provide some layman’s terms/examples? This would be my first EV so I’m sure there are some factors I’m excluding. Thanks.
Duckrider is blowing smoke. If 40 amp or 48 amp doesn't fill his needs he will have to use a fast DC charger or just stay with an ICE. At the moment I'm charging my Bolt with my Level 2. It only excepts 32 amps and it is just fine. Everyone's needs are different.
 

Fenwayfan77

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Duckrider is blowing smoke. If 40 amp or 48 amp doesn't fill his needs he will have to use a fast DC charger or just stay with an ICE. At the moment I'm charging my Bolt with my Level 2. It only excepts 32 amps and it is just fine. Everyone's needs are different.
Another interesting take. Thanks. I'm currently firing up the popcorn maker before the show commences on this topic!! lol.
 

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DucRider

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Interesting. From what I’ve read and watched to date, which apparently were the wrong sources if what you’re saying is correct, even 32A would be mostly sufficient. FYI. I’m not looking to fill the vehicle from empty every night. I highly doubt I’d be even 1/3 to half empty 95 percent of the time.

Would you be willing to provide some layman’s terms/examples? This would be my first EV so I’m sure there are some factors I’m excluding. Thanks.
I'm not DucRider (I ride an HP4), but my charging needs are simple enough for my current EV (an i3s, range about 120 miles) that I just plug it into the 110 outlet every night. It takes 2 nights to fill from empty. Daily use is probably 40 miles. When we need to go farther we hit a local DC fast charger for an hour-ish, or take the smog generator (the other BMW). After getting comfortable with EVs you do the slightly more necessary refuel planning without much effort.
Plugging into a standard 120V outlet:
This will likely be enough for at least some to cover their daily use, but you will (almost certainly) get only 1.4 kW when doing so. The Rivians will be much less efficient than the i3 of @thrill , so the range you gain overnight will be less. Until we get some actual numbers, a conservative estimate would be 2 miles for every hour you plug in to a standard 120V outlet. It is likely to be a bit more than that under ideal conditions, but could actually be less than that in cold weather (efficiency and range both decrease). Often there are other drawbacks to 120V (Level 1) charging as well. Heating/cooling the battery while charging is sometimes limited (necessary under some conditions) and further slows the charging process. Also, one of the strategies to maximize cold/hot weather range (or purely for comfort) is to precondition the cabin while connected to "shore power" without using the vehicles battery and this is often not possible when connected to 120V.

Advantages to 240V:
In addition to faster speed, the ability to precondition the cabin and heat/cool the battery while charging (a very good thing) is greatly enhanced. New owners of EVs are often worried when they hear all kinds of fan and coolant noise while their vehicle is "off" but charging - most often on hot days if charging starts immediately after driving but can occur anytime.
As to speed and how "big" of an EVSE and circuit you need?
Ballpark numbers at this point look like between 2 and 2.5 miles per kWh.
A 30A circuit can support a 24A EVSE (multiply breaker size by .8 to get the maximum amperage of the EVSE it can handle). A 40A circuit a 32A EVSE, etc. The maximum the Rivians will support is 48A.
How to convert that to approximate miles?
32A x 240V = 7.7 kW
If you charge for 10 hours, that would be 77 kWh (8 hours would be ~62 kWh)
77 kWh times 2 miles per kWh equals about 150 miles of range. If you figure 2.5 miles/kWh that would get you about 190 miles.
These range numbers are based off of conditions close the the EPA testing parameters. If you drive in cold or hot weather, at elevated speeds or are towing, those will all have an impact.

Even if you don't need the added overnight range a 240V EVSE can provide, I do recommend one for not only the preconditioning and battery conditioning benefit, but also the ability to schedule your charging for non-peak hours and have it completed in that window. If you have a Time of Use plan, this can have a big financial benefit. Even if you don't have TOU, it is "better for the grid" to charge when other demand is low.
 

DucRider

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Duckrider is blowing smoke. If 40 amp or 48 amp doesn't fill his needs he will have to use a fast DC charger or just stay with an ICE. At the moment I'm charging my Bolt with my Level 2. It only excepts 32 amps and it is just fine. Everyone's needs are different.
I think @DucRider 's point was simply that there aren't too many use cases where 48A is enough, but 40A isn't.
Exactly.
A 32A EVSE will likely be more than adequate for 90% of the people 90% of the time (and the OEM charge cord included with the vehicle will do just that)
 

Fenwayfan77

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Plugging into a standard 120V outlet:
This will likely be enough for at least some to cover their daily use, but you will (almost certainly) get only 1.4 kW when doing so. The Rivians will be much less efficient than the i3 of @thrill , so the range you gain overnight will be less. Until we get some actual numbers, a conservative estimate would be 2 miles for every hour you plug in to a standard 120V outlet. It is likely to be a bit more than that under ideal conditions, but could actually be less than that in cold weather (efficiency and range both decrease). Often there are other drawbacks to 120V (Level 1) charging as well. Heating/cooling the battery while charging is sometimes limited (necessary under some conditions) and further slows the charging process. Also, one of the strategies to maximize cold/hot weather range (or purely for comfort) is to precondition the cabin while connected to "shore power" without using the vehicles battery and this is often not possible when connected to 120V.

Advantages to 240V:
In addition to faster speed, the ability to precondition the cabin and heat/cool the battery while charging (a very good thing) is greatly enhanced. New owners of EVs are often worried when they hear all kinds of fan and coolant noise while their vehicle is "off" but charging - most often on hot days if charging starts immediately after driving but can occur anytime.
As to speed and how "big" of an EVSE and circuit you need?
Ballpark numbers at this point look like between 2 and 2.5 miles per kWh.
A 30A circuit can support a 24A EVSE (multiply breaker size by .8 to get the maximum amperage of the EVSE it can handle). A 40A circuit a 32A EVSE, etc. The maximum the Rivians will support is 48A.
How to convert that to approximate miles?
32A x 240V = 7.7 kW
If you charge for 10 hours, that would be 77 kWh (8 hours would be ~62 kWh)
77 kWh times 2 miles per kWh equals about 150 miles of range. If you figure 2.5 miles/kWh that would get you about 190 miles.
These range numbers are based off of conditions close the the EPA testing parameters. If you drive in cold or hot weather, at elevated speeds or are towing, those will all have an impact.

Even if you don't need the added overnight range a 240V EVSE can provide, I do recommend one for not only the preconditioning and battery conditioning benefit, but also the ability to schedule your charging for non-peak hours and have it completed in that window. If you have a Time of Use plan, this can have a big financial benefit. Even if you don't have TOU, it is "better for the grid" to charge when other demand is low.
Thanks for the numbers breakdown. Based on that, and when looking at my particular expected use/needs, I still feel the 40A will more than suffice for me. Good to know the calculations though for future reference.

The 2 and 2.5 miles per kWh hour reference is an interesting mention. Worth a further look. Will be interested to hear about real world examples.

Thanks,
 

davrow_R1T

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Would you be willing to provide some layman’s terms/examples? This would be my first EV so I’m sure there are some factors I’m excluding. Thanks.
Experience will teach you a lot, it's true. I've had two EVs (no Teslas). The most recent one had a hardwired charger in the garage... until I moved. Never bothered re-installing it, just charged on 110 for the next two years.

We have more than 1 car, the EV was my commuter. Rarely more than 50 miles a day. Even on 110 it could finish charging on TOU off-peak.
 

DucRider

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Experience will teach you a lot, it's true. I've had two EVs (no Teslas). The most recent one had a hardwired charger in the garage... until I moved. Never bothered re-installing it, just charged on 110 for the next two years.

We have more than 1 car, the EV was my commuter. Rarely more than 50 miles a day. Even on 110 it could finish charging on TOU off-peak.
The Rivian will be a much less efficient EV that you are used to and require longer to charge to get the same number of miles.

300 miles/135 kWh = 2.22 miles per kWh
50 miles/2.22 = 22.5 kWh
A 120V EVSE on a 15A circuit will provide 1.44 kW
22.5 kWh/1.44 kW = 15.6 hours. This will rarely fit into off peak TOU.
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