Beginners' guide to EV charging?

[pcrampton]

I'm an EV newbie. I've ordered the R1S and it's my first EV.

Is there an easy-to-understand beginner's guide to the charging information? I'm getting overwhelmed with the number of watts to distance.

I get that the R1S will regenerate power during driving but I am mathematically challenged and get overwhelmed.

I'd like to get more educated but not at a Ph.D. level yet.

Suggestions?

Thanks!

Sponsored

 

[SeaGeo]

Yeah, give me a few and I'll give you some videos to watch that I think are helpful.

 

[Matt D.]

Also, for home charging I know that a 60amp circuit will charge faster but are there any reasons to go with a 50amp instead?

 

[SeaGeo]

General tips on charging EVs from Kyle (out of spec)


Beginners guide from fully charged:



TBH, I'd recommend watching a few of their road trip videos from the OutOfSpecMotoring youtube channel. It sounds a bit weird, but my wife and I find them interesting to watch, and it lets you experience living with an EV vicariously, and see some of the issues you may/may not run into. Since you're buying an R1S, I'd generally suggest the non-tesla road tripping videos they have, but there's still a lot to gain from watching the Tesla ones. Just be aware that Tesla's faster chargers are not compatible with other brands (ie Rivian).

Cold weather charging and road tripping tips:




A quick summary that I'm sure others

as you picked up, kilowatt hours is the "volume" of energy. It's basically your gallons of gas.

Roughly speaking, the R1T should take about 0.5 kWh to travel a mile.

There are 3 general levels of charging.
https://www.forbes.com/wheels/advice/ev-charging-levels/

Level 1 is your regular home outlet. It'll give about a 1.3 to 2.3 kW. So if you plug in for an hour, you'll get 1.3 to 2.3 kWh.

Level 2 is 220/240v in the U.S., and the kW will vary by amperage. The fastest the R1T can charge is 11.5 kW. So 11.5*~2.17 = 25 miles of charge added per hour with a level 2 charger that provides 40 amps of charge.

Level 3 is the DC fast charging. This is where the most uncertainty and frustration comes in. There are a lot of different networks and each has it's own quirks and reliability issues generally. Broadly speaking DC charging can be split up into stations that put out ~ 50 kw, 150kw, and 350kW.

The R1T (currently) can pull at most about 200kW, but that is very dependent on the station and how warm the battery is, and what your state of charge is. Generally EVs will charge fastest down in the 10 to 30% range, and they slow down as they approach 100%. Elon Musk uses the analogy that as you approach 100%, it's harder and harder to find places to put the electrons, so you have to be more careful - so it's sort of like filling up a water bucket. You can turn your hose on full blast and not worry about over filling it, but as you approach full you have to be careful not to spill over.

Rivian says you can charge the R1S and R1T at up to 140 miles/20 minutes. If you do the math, that's basically 190 to 200 kw over that 20 minutes.

 

[SeaGeo]

Also, for home charging I know that a 60amp circuit will charge faster but are there any reasons to go with a 50amp instead?

So this is where things get a bit confusing. The R1S and R1T can charge at most 11.5 kW on AC charging. That's the max output of the AC-->DC converter that the car has. A 240v outlet at 48 amps is 11.5kW. However, per the building code (and there are some intricacies here that others will probably jump on) your fuse needs to be 25% (20?%) greater than the continuous power usage. So 48*1.25 = 60 amps. ANything more than 60 amps would return no gain for the RIvian, but it would for a couple of other cars that can charge at higher amperage on level 2.

THat being said, realistically the difference between a 40 amp charger (50 amp fuse) and 48 amp charger (60 amp fuse) probably doesn't matter as you'll generally be charging it over night, and over the course of an hour that's only 1.9kW difference in charge. So you'll only pick up ~ 4 extra miles per hour.

 

[harkco]

So this is where things get a bit confusing. The R1S and R1T can charge at most 11.5 kW on AC charging. That's the max output of the AC-->DC converter that the car has. A 240v outlet at 48 amps is 11.5kW. However, per the building code (and there are some intricacies here that others will probably jump on) your fuse needs to be 25% (20?%) greater than the continuous power usage. So 48*1.25 = 60 amps. ANything more than 60 amps would return no gain for the RIvian, but it would for a couple of other cars that can charge at higher amperage on level 2.

THat being said, realistically the difference between a 40 amp charger (50 amp fuse) and 48 amp charger (60 amp fuse) probably doesn't matter as you'll generally be charging it over night, and over the course of an hour that's only 1.9kW difference in charge. So you'll only pick up ~ 4 extra miles per hour.

Hey SeaGeo - thanks for all the information! We should almost sticky the post in the forum. There will be lots of people (like myself) that the R1T or S will be their first electric vehicle.

 

[pcrampton]

General tips on charging EVs from Kyle (out of spec)


Beginners guide from fully charged:



TBH, I'd recommend watching a few of their road trip videos from the OutOfSpecMotoring youtube channel. It sounds a bit weird, but my wife and I find them interesting to watch, and it lets you experience living with an EV vicariously, and see some of the issues you may/may not run into. Since you're buying an R1S, I'd generally suggest the non-tesla road tripping videos they have, but there's still a lot to gain from watching the Tesla ones. Just be aware that Tesla's faster chargers are not compatible with other brands (ie Rivian).

Cold weather charging and road tripping tips:




A quick summary that I'm sure others

as you picked up, kilowatt hours is the "volume" of energy. It's basically your gallons of gas.

Roughly speaking, the R1T should take about 2 to 2.5 kWh to travel a mile.

There are 3 general levels of charging.
https://www.forbes.com/wheels/advice/ev-charging-levels/


Elon Musk uses the analogy that as you approach 100%, it's harder and harder to find places to put the electrons, so you have to be more careful - so it's sort of like filling up a water bucket. You can turn your hose on full blast and not worry about over filling it, but as you approach full you have to be careful not to spill over.

WOW! Really helpful! Thank you!!

You wrote that the temp of the battery impacts how fast or how much charge it can receive? Does this mean I will have an easier time charging quickly/going longer distances because I live in the Palm Springs, CA area? i.e.; the desert.

It gets HOT here - 115* F is pretty common during the summer.

 

[SeaGeo]

WOW! Really helpful! Thank you!!

You wrote that the temp of the battery impacts how fast or how much charge it can receive? Does this mean I will have an easier time charging quickly/going longer distances because I live in the Palm Springs, CA area? i.e.; the desert.

It gets HOT here - 115* F is pretty common during the summer.

Haha, well you're potentially running into the opposite issue. You can get temperatures that are too hot for the battery and it throttles due to overheating basically.

Generally speaking, the most manufacturers will try to have the battery sit between 80 and 90 degrees F to optimize charging. Some will actively manage that if you have a DC fast charging station put into the car navigation, some don't. As far as I can recall, all modern cars will actively heat and cool the battery to within a safe range with a liquid cooling system (except the leaf, don't buy a leaf). That is mostly to help with longevity of the battery. As with your old AA batteries, you don't want to stick your car battery in a freezer for a long time, or in the oven.

That being said, the Rivian will actively cool the battery, and I expect that they'll have battery preconditioning enabled. If you arrive to a charger and it's too hot, you'll just get lower speeds until the cooling system kicks in enough to get the temp into the ideal range.

Bjorn is a youtuber in Norway who does a lot of great EV testing, and he has a nice video explaining this (referred to as rapidgating) with the EV6. Basically the Ioniq5 and EV6 charge so incredibly fast that they tend to hit their thermal limit, and then the charging speed temporarily slows down till the HVAC system can catch up, and then it will speed up again. So they both are pretty susceptible to outside temperatures.


At the moment they don't have preconditioning either to warm the battery up (this will be an OTA with those two cars). So just driving them around when it's cold frequently won't warm the battery up enough to optimize charging speeds. Contextually they still charge quite fast, just not the insane speeds that Kia and Hyundai quote.


This is a neat video from Bjorn that shows the cold issue with the Mercedes EQS as well:

at about 4:45 you can see that he gets 70kw charging the EQS, and he explains what he didn't precondition the battery yet. But if you compare that to his fast charging test below, when properly warmed up the car pulled ~180 kw at 40%.

 

[nukem384]

Also, for home charging I know that a 60amp circuit will charge faster but are there any reasons to go with a 50amp instead?

It's really all about time. If you have a long TOU (time of use) rate through your utility company, it really doesn't matter. A 50A breaker is fine because putting in a NEMA 14-50 will be cheaper than a wall charger. Sure, it'll charge slower 15MPH vs 25MPH, but who cares when the car is just sitting there while you are sleeping. That's really the only difference. If you need the car to charge faster because you have a crappy TOU rate, then the faster makes sense in that scenario.

 

[Matt D.]

It's really all about time. If you have a long TOU (time of use) rate through your utility company, it really doesn't matter. A 50A breaker is fine because putting in a NEMA 14-50 will be cheaper than a wall charger. Sure, it'll charge slower 15MPH vs 25MPH, but who cares when the car is just sitting there while you are sleeping. That's really the only difference. If you need the car to charge faster because you have a crappy TOU rate, then the faster makes sense in that scenario.

I’ve ordered the Rivian charger. I have a constant (24 hour) fixed rate for electricity. I have an electrician buddy who can do the install for a very reasonable rate. I just didn’t know if there are any drawbacks to the 60 amp fuse.

 

[SeaGeo]

I’ve ordered the Rivian charger. I have a constant (24 hour) fixed rate for electricity. I have an electrician buddy who can do the install for a very reasonable rate. I just didn’t know if there are any drawbacks to the 60 amp fuse.

not really. He'll be able to tell you if you're limited by your breaker or service. Otherwise you're just deciding how much you want to future proof for other vehicles that may have a higher powered onboard charger and if you need that. Personally I don't see much of a use case.

 

[nukem384]

I’ve ordered the Rivian charger. I have a constant (24 hour) fixed rate for electricity. I have an electrician buddy who can do the install for a very reasonable rate. I just didn’t know if there are any drawbacks to the 60 amp fuse.

oOOooo if you're on a fixed rate, NEMA 14-50 would've been the better way to go, financial wise. Install is install no matter the wall charger or the NEMA 14-50, and then the wall charger is going to be extra after that (to purchase the unit). But, the wall charger does look nice. No drawbacks to having a 60A breaker. It'll charge you faster as long as you don't go over 48A for constant load. (80% full load is the max you can safely go without risking causing a fire, 48/60 = 80%)

 

[SeaGeo]

oOOooo if you're on a fixed rate, NEMA 14-50 would've been the better way to go, financial wise. Install is install no matter the wall charger or the NEMA 14-50, and then the wall charger is going to be extra after that (to purchase the unit). But, the wall charger does look nice. No drawbacks to having a 60A breaker. It'll charge you faster as long as you don't go over 48A for constant load. (80% full load is the max you can safely go without risking causing a fire, 48/60 = 80%)

I hardwired mine, but I've heard from multiple people that having a 14-50 ,that's to current code tends to cause you to trip a breaker IIRC.

 

[pcrampton]

I"m so confused! Hard wired charger install or not?

I ordered the Rivian wall and remote chargers. As a first-time electric owner, I'm going to be as prepared as possible!

I live in the Southern California desert, in a condo association, in a townhome; which I own. I have a private garage attached to my unit.

My power panel is upstairs in the main bedroom closet. and my washer and dryer are located in a room connected to the garage.

I think I have 2 open slots in my electric panel. See photo.

Am I a good candidate for the wall charger install?

 

[nukem384]

I hardwired mine, but I've heard from multiple people that having a 14-50 ,that's to current code tends to cause you to trip a breaker IIRC.

I guess I'll find out if I ever get the S we preordered lol. Already have a 14-50 for my Tesla. I'm assuming you can control amps from the screen? Not that it matters tho since the mobile charger maxs at 32A anyway.

Sponsored