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First Time EV Buyers: Battery Size and Charging Apprehensions

Riventures

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For first-time EV buyers: I hadn't considered an EV until I heard of the R1T. It was the first EV that really spoke to me, got me excited. I placed my pre-order last July, joined this community, started looking into battery technologies and everything related to energy generation in the US preparing for EV ownership.

One of the preparation items was home charging, planning the garage, additional circuit(s), etc. The plans were all laid out in a way that I was finally convinced I would not need the max battery pack and could spend that money modernizing our home's electrical systems.

Unfortunately, recently I came to the realization that the R1T is not going to meet my needs or desires, so I reluctantly canceled my order. Instead, I bought another EV that has only ~250-mile range on a good day, and it is a sedan, not an SUV or truck. I have to admit that it was probably a great decision for us. I spent my first week with it in joy, comfort, and everything that EVs promise. Yesterday, the battery pack was down to 29%, so I went to charge it at a public Electrify America station nearby. At the same time, electricians have been in the house providing me estimates for all the work that was planned. There have been many bad stories around Electrify America, so I knew I could not rely on them for charging on a regular basis, so part of the plan at home was to install a 19.2 kWh charger, which requires a 100 amp circuit. A bit pricey, but I thought it is worth it in the long run.

The Electrify America stations (10+ of them) are within 3 mi. radius from where I live. I picked one charging cluster near a large shopping outlet, went there late evening, found the place very well lit with empty chargers. It was 150 kWh DCFC, I connected the car, opened the app, hit "Start Charger" and voila! After negotiating with the car for about 3 mins, it started charging at 99 kWh, increasing to about 103-105 for the remainder. 18 mins later I was at 70% charge, good enough, and I stopped the charge. In the meantime, I stayed in the car, warm and comfortable, checking emails, replying to text messages, having a hot coffee. The process was not only painless, but dare I say, even enjoyable.

Now I am thinking, I may not even need a home charger. Everything worked well from first connection to disconnection, I enjoyed the quiet time, was not in danger of anything, and even at only 100 kWh charging (the car can go as high as 250 kWh), it was fast enough for me.

So, if you don't have experience with EVs, like me, and are apprehensive about charging, don't be, I think we will be alright :like:
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OEVA

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19.2kW is overkill for 99% of use cases.
1.44kW on a 120V circuit is adequate for a fairly large percentage of people for their daily needs.
A 40 or 50A circuit is pretty much the "sweet spot" for home charging. Going to L2 (240V) helps a bunch with inefficient EVs (like the Rivian), and also allows for shorter charge times to better fit TOU plans (or just charging when it is better for the grid even without financial incentive). It is also usually recommended for preconditioning when temps are cold or extremely hot.

DCFC is harder on the battery, so charging overnight from AC is usually recommended when available. While you enjoyed your time charging, that may not always be the case. Being able to "fill the tank" while sleeping is a benefit that shouldn't be overlooked.

Long term, you will likely find home charging to be worth the cost of installation. Dropping to a 50 or 60A circuit from the 100A you were planning will likely save some money.
 
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Riventures

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I am sure you are right about home charging. The car comes with a 120V mobile charger, which is inadequate for charging, but more than enough for overnight conditioning of the batteries. At least that is my presumption at this time.

We shall see :)
 

Mjhirsch78

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Thank you for that post @Riventures. Congrats on your fun new vehicle! We had a similar experience buying our first EV in March. It is fun to drive and easy to charge. I would think about at least a 40 or 50 amp plug in the garage just for long term cost of charging as EA will be 30-40 cents/kWh versus home being 7-16 cents/kWh. We have put 18k miles on since March and saved more than $2k in fuel costs with 90% home charging.
 

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I am sure you are right about home charging. The car comes with a 120V mobile charger, which is inadequate for charging, but more than enough for overnight conditioning of the batteries. At least that is my presumption at this time.

We shall see :)
The 120v charger at about 3.5 mph charging rate is perfectly adequate if your daily usage is within the daily American average of 25 miles.
 

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What EV did you get?
 

SeaGeo

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Not the most efficient, nor fastest, but I am loving it thus far :)
Nice! We almost bought a used one about a year ago. Great charging curve, and so comfy. Weird thing to remember, but they have my favorite wireless phone charging location of any car I've seen.

Also not a sedan. Lol.
 
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Riventures

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Yes! The wireless CarPlay also works flawlessly. However, the most impressive for me has been the headlights. I would not have believed it if I hadn’t used it myself. Just so very intelligent how it continuously adjusts the laser lights for maximum visibility without blinding others.
 

atR1S

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If rivian doesn’t pan out for me the e-tron is probably next on my list. I hope to test drive one next week.
 

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BobK

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19.2kW is overkill for 99% of use cases.

A 40 or 50A circuit is pretty much the "sweet spot" for home charging. Going to L2 (240V) helps a bunch with inefficient EVs (like the Rivian), and also allows for shorter charge times to better fit TOU plans (or just charging when it is better for the grid even without financial incentive). It is also usually recommended for preconditioning when temps are cold or extremely hot.

DCFC is harder on the battery, so charging overnight from AC is usually recommended when available. While you enjoyed your time charging, that may not always be the case. Being able to "fill the tank" while sleeping is a benefit that shouldn't be overlooked.

Long term, you will likely find home charging to be worth the cost of installation. Dropping to a 50 or 60A circuit from the 100A you were planning will likely save some money.
Wondering if you could expand on your statement regarding precondtioining-or point me to a website or two that explains this.
Thinking ahead to when a household might have two or more EV's-does it make sense to consider the 100 amp option?
Thanks

Bob

PS As background-in metro Chicago(cold!), on the local power grid TOU pricing, and have PV-though will need more panels to accommodate EV
 

Craigins

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Wondering if you could expand on your statement regarding precondtioining-or point me to a website or two that explains this.
Thinking ahead to when a household might have two or more EV's-does it make sense to consider the 100 amp option?
Thanks

Bob

PS As background-in metro Chicago(cold!), on the local power grid TOU pricing, and have PV-though will need more panels to accommodate EV
You want to precondition in order to heat/cool the vehicle and battery using power from the wall. Batteries are most efficient in a specific temperature range and will use energy to reach that range.

This is why my prius c gets 30mpg in the winter in Chicago compared to the 60 in the summer. In my 10 min commute, it spends all the energy running the gas engine to heat the battery system.
 

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The small battery systems in PHEVs are notoriously less efficient than full size BEVs when it comes to thermal management and cold performance. That said, cold weather is still an issue and we don't know how well Rivian has designed their thermal system. We found with our 2016 Model X that if we just jumped in the car on a cold day, our range could be reduced significantly. Immediately onto the highway and the drain would be massive pushing a cold battery to drive the car fast. Our 2020 Model Y has a hugely upgraded heat pump system and fares way better in this regard. Parking in the garage also helps as there's less to pre-condition if the battery is already at 45°F vs. sitting in the driveway at 20°F. Even if not plugged in we have found that when it's close to freezing or below outside, it's best to pre-condition before driving, especially if the car has been parked out in the cold.

The amount of energy used to slowly warm the battery for a few minutes is a lot less than the amount of energy wasted trying to force a cold battery to do real work.
 

OEVA

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Wondering if you could expand on your statement regarding precondtioining-or point me to a website or two that explains this.
Thinking ahead to when a household might have two or more EV's-does it make sense to consider the 100 amp option?
Thanks

Bob

PS As background-in metro Chicago(cold!), on the local power grid TOU pricing, and have PV-though will need more panels to accommodate EV
Preconditioning will take much more power than L1 (120V) can provide. Not uncommon to see a 32A draw with a full battery (or one already "fully charged" to the level set by the user).
Not only is it pleasant to get into a prewarmed vehicle, it also allows the battery to be brought to a more optimal operating temperature (as noted above in a couple of posts).
Rivian stated in their cold weather testing video that they use a very active strategy to keep the batteries warm. Being plugged in while it does so will retain your desired charge level.
Rivian R1T R1S First Time EV Buyers: Battery Size and Charging Apprehensions 1638894215254


https://electrek.co/2021/02/27/rivian-tests-r1t-electric-pickup-in-sub-zero-temperatures/
 

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it's been a while since I checked but 100A for a single charger is overkill because most AC charging systems in everything but original Model X/S stop at 60A.

Now, 100A to put two say 40A behind is a great idea. but I'd buy at most a 32A or 40A charger for the home, anything more just gets more and more expensive with smaller results.

Been driving EVs on 60-80 mile commutes since 2017, while I haven't driven as much since Covid 32-40A (7.2 to 9.6kw) charger is plenty even for a 100kwh battery. even if you pull in at 2% in eight or so hours it's full. (rounding a bit). Plug in, go to bed, get up, car is charged.

EA and other fast charging is great, if you're only going to keep the car for a few years and don't care about the battery life fast charge it all you want.

Longevity wise that battery will lose it's oomf.

Congrats on the etron, i was days away from getting one before deciding to wait out the R1T Max Pack for now. It's a beauty, and I'm a huge fan of Audi. I've owned the TT Roadster, A4 Cabriolet, allroad, A5, and SQ5 over the years.

With me not going back into the office still the need for a third vehicle at our house is low, so I'm saving the payments each month to put down on the R1T when it finally gets here. My fallback car if I give up is a toss up between the etron S and etron, sportback. Though my work has tons of free 30A chargers to use while you park at work :)
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