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Help me understand a home charging setup

BigSkies

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Hey everyone,

At the moment, I have zero EV's, but we plan to replace both of our cars with EV's over the next few years. This isn't a Rivian specific question, but I'm trying to be sure I set things up in a way that won't require changing anything for a Rivian.

I'm having an electrician out to quote some unrelated work, and I'm debating if it makes sense to get a 40A or 50A 240V outlet installed while I'm doing the other work. I also do some hobbyist woodworking in my garage, and not having a 240V outlet has been a limiting factor on the tools I've bought. We don't drive a ton, so a single charger would probably work for the two cars.

For cars, my wife is looking at the Model 3 or the Mustang Mach-E. We might also take a look at the new Kia/Hyandai options coming out next year. I'm hoping the R1S is in my budget, but my wife will likely get her car first.

Here's my questions:

1. Help me understand the value-add (or loss) from buying the Tesla or Rivian branded chargers compared with a generic one. I believe (possibly incorrectly) that the Tesla charger only comes in a hardwired setup, which I would prefer to avoid.
2. How impractical is it if I mount the charger on one side of the garage, but the charge-port ends up being on the opposite side of the car?
3. I like the idea of having a 240V outlet in the garage to use for bigger power tools on occasion. Is there any benefit of a hardwired setup I'm missing?
4. If a generic charger is best for my situation, are there any specific features I should look out for?
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nfrank

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Don’t buy a Tesla branded charger, it’ll limit you. Rivian’s will be a generic charger with their logo. It’s actually a fair price at $500 so I’m getting that. Always buy the charger with the longest cable.

Wired chargers are on 60 amp services and charge 20% faster. Your best solution is to ask the electrician to pull a 60 amp service to your garage and have a small sub panel to switch between your wired charger and a 50 amp breaker tied to a NEMA 14-50 outlet. That’ll be the best of both worlds.

Check your utility. The chargers with the best feature is the one you can get paid for via rebates. Call and ask and buy specifically what they discount.
 

CommodoreAmiga

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1. Help me understand the value-add (or loss) from buying the Tesla or Rivian branded chargers compared with a generic one. I believe (possibly incorrectly) that the Tesla charger only comes in a hardwired setup, which I would prefer to avoid.
The Rivian charger is $500 if you buy it at the same time as a Rivian vehicle. Given it's charging speed, proposed feature set, and warranty this is an excellent price/value. The integration with the Rivian app will also be a nice bonus. I think this is probably the best option for people willing to hardwire their EVSE and who don't already have one.

2. How impractical is it if I mount the charger on one side of the garage, but the charge-port ends
up being on the opposite side of the car?
A good EVSE will have a cable between 20-25' long. You'll need to determine if that will work for your situation.

3. I like the idea of having a 240V outlet in the garage to use for bigger power tools on occasion. Is there any benefit of a hardwired setup I'm missing?
Yes. Hardwired EVSEs are allowed to draw more power. For example, the Rivian EVSE can go up to 48A when hardwired. Plug-in EVSEs are limited to only 40A. Another benefit is reliability. Code requirements in many jurisdictions require GFCI on "plug in" circuits, and EVSEs are known for tripping GFCIs. Hardwired is also safer, imo.

I would always prefer a hardwired setup whenever possible. If you want an outlet to be able to plug in a cabinet saw, welder, or other large tool then you can add that as a separate breaker, imo.

4. If a generic charger is best for my situation, are there any specific features I should look out for?
The OpenEVSE is the least expensive option I'd consider, personally. It's a nice design and the open-source nature is desirable, to me. The downside is it lacks certifications -- because there's no big company backing the project to pay for them.

The HomePoint Charge Flex was going to be my personal choice, prior to Rivian unveiling their own EVSE. I'd still suggest this EVSE to anyone who doesn't want a branded unit.

The core function of EVSEs is quite simple. The primary difference between EVSEs on the market is in the "niceties" like longer and more flexible cables, WiFi connectivity and apps, warranties, etc.

Tom Moloughney on YouTube has some excellent and thorough reviews of many EVSE options. If you're ever bored, check out some of his videos.
 

ajdelange

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Here's my questions:

1. Help me understand the value-add (or loss) from buying the Tesla or Rivian branded chargers compared with a generic one. I believe (possibly incorrectly) that the Tesla charger only comes in a hardwired setup, which I would prefer to avoid.
At the moment Tesla is only offered in a hard wired form and I believe the same is true of the Rivian. Of course in either case it is a simple matter to obtain a proper gland, a bit of SJO and a plug and you have a plug-in version. Rivian has evidently hinted, through CS, that it is preferred that you do not do that. If you do there are implications on code conformance and it is doubtless best that you hard wire these units. Your reward for doing so is 48A charging rate (as long as large enough, AWG 6, wire is used with a 60A breaker. With the plug-in versions you are limited to 32 or 40 A.

2. How impractical is it if I mount the charger on one side of the garage, but the charge-port ends up being on the opposite side of the car?
That depends on the vehicle and the cord. There are cord management solutions that lend a lot of flexibilty. What you want to avoid is uncoiling and coiling cord each time you plug/unplug.


3. I like the idea of having a 240V outlet in the garage to use for bigger power tools on occasion. Is there any benefit of a hardwired setup I'm missing?
Other than the higher charging rate, no and one disadvantage: the EVSE is the only thing allowed to be on a charging branch circuit. The same is technically true of a 14-50R outlet but how is the inspector to know that a 14-50R is a charging circuit?

4. If a generic charger is best for my situation, are there any specific features I should look out for?
Let's note that the Rivian and Tesla hard wired units are generic in the sense that you can charge a Tesla from a Rivian EVSE and conversely. The same is true of any other generic charger which is going to come with a J1772 connector. The thing to look for is laboratory rating (UL, CE etc.). This insures the device is safe.
 
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BigSkies

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Thank you everyone! This is just what I was looking for.

One of the big questions for the electrician will be how much more room I have on my panel. I have long term plans to convert most of my house away from natural gas and add a bunch of solar. We'll see how much room I have before I need to upgrade the main panel (which I'd like to avoid).
 

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ajdelange

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This can go down so many paths. You may need bigger service. If the service is sufficient you can usually get extra breakers in by replacing old ones with the newer skinny style. This does require that the stabs on the existing panel will take these.
 

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Tell your electrician to review the NEC (National Electric Code) Article 625. There are some unique requirements in the Article that an electrician might overlook.
 

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Make sure to check how many amps you actually have going to the garage. This is an issue for me. I only have 50 Amps. So I either have to use the included portable charger or install the Rivian branded charger and down rate it to 35-38 Amps. I will probably do the latter and at some point get more power to the garage.
 

EarlyAdptr

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What you want to avoid is uncoiling and coiling cord each time you plug/unplug.
Why is that @ajdelange ? Just because it's a pain in the ass or is there some technical problem if that happens repeatedly?
 

ajdelange

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Why is that @ajdelange ? Just because it's a pain in the ass or is there some technical problem if that happens repeatedly?
Both. It's so very convenient to be able to push the garage door close button with one hand while you grab the wand and move it to the car with the other. Thus you want to mount the charger right next to the charge port if you can. If the EVSE is next to the driver side rear fender and the charge port on passenger right fender then you have to unwind cable, drag it around to the passenger side and plug it in. This will involve draping it over the car or trailing it along the floor. When it is time to put it back you will find that you have to wind it in a particular way or it won't coil neatly. Dragging it agross the floor gets it dirty so your installation does not appear so neat. All the manipulation will accelerate cable wear.

All these problems can be solved with pantographs and retractable wires that attach to the cable and keep it off the floor.
 

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ajdelange

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nukem384

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Hey everyone,

At the moment, I have zero EV's, but we plan to replace both of our cars with EV's over the next few years. This isn't a Rivian specific question, but I'm trying to be sure I set things up in a way that won't require changing anything for a Rivian.

I'm having an electrician out to quote some unrelated work, and I'm debating if it makes sense to get a 40A or 50A 240V outlet installed while I'm doing the other work. I also do some hobbyist woodworking in my garage, and not having a 240V outlet has been a limiting factor on the tools I've bought. We don't drive a ton, so a single charger would probably work for the two cars.

For cars, my wife is looking at the Model 3 or the Mustang Mach-E. We might also take a look at the new Kia/Hyandai options coming out next year. I'm hoping the R1S is in my budget, but my wife will likely get her car first.

Here's my questions:

1. Help me understand the value-add (or loss) from buying the Tesla or Rivian branded chargers compared with a generic one. I believe (possibly incorrectly) that the Tesla charger only comes in a hardwired setup, which I would prefer to avoid.
2. How impractical is it if I mount the charger on one side of the garage, but the charge-port ends up being on the opposite side of the car?
3. I like the idea of having a 240V outlet in the garage to use for bigger power tools on occasion. Is there any benefit of a hardwired setup I'm missing?
4. If a generic charger is best for my situation, are there any specific features I should look out for?
All you really need is a NEMA 14-50. It's a 50A receptacle and will charge a Rivian 15MPH I believe because of how big the battery is. If you were to get a Model 3, it'd charge at 30MPH. It's universal, so any car can charge on that receptacle. Both R1's mobile charger comes with the NEMA 14-50 as the plug in, so you're ready to go. I think most EV's use this plug to charge.

The Rivian wall charger would be a better bet than the Tesla wall charger if you wanted a little more power. This one needs to be on a 60A breaker because it can go up to 48A. It's also universal and can charge any car that has the J1772 charge port (which is basically all EV's besides Tesla's).

The cords are pretty long. Even my mobile charger cord for my Model 3 is like 20' long? So there probably won't be an issue with length. If there is though, can you always get an extension cord. Just make sure it's from a quality company since we don't want any fires starting from cheap materials.
 

ajdelange

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All you really need is a NEMA 14-50. It's a 50A receptacle and will charge a Rivian 15MPH I believe because of how big the battery is.
It can charge a RIT at 16 mph or 20 mph. Using the charging connector that comes with the truck It charges at 16 mph because, while it is a 50 amp receptacle it can legally be installed on a 40 A circuit in which case the most you can take from it for charging is 32 A. Rivian, as does Tesla, takes the conservative path and assumes that your wiring is 40A. Thus their portable EVSE delivers 32*240 = 7680 W. Their newly released data indicates that the car requires 480 W to charge a mile's worth and so the rate is 32*240/480 = 16 miles per hour.

If you were to get a Model 3, it'd charge at 30MPH.
That's because the S requires but 256 W of charge to add a mile. Thus it is the conumption that determines the charging speed in mph - not the battery size.


It's universal, so any car can charge on that receptacle. Both R1's mobile charger comes with the NEMA 14-50 as the plug in, so you're ready to go. I think most EV's use this plug to charge.
A NEMA 14-50R on a 50A circuit can be legally used to supply any intermittant load up to 50A and a continuous load (which, by definition, a car charger is) up to 40A. You can, therefore, plug any EVSE into it as long as that EVSE is set to limit charging rate to 40A. The portable EVSE that come with the cars assume, as noted above, that the receptacle is on a 40A circuit and this only allow the car to take 32A.


The Rivian wall charger would be a better bet than the Tesla wall charger if you wanted a little more power. This one needs to be on a 60A breaker because it can go up to 48A. It's also universal and can charge any car that has the J1772 charge port (which is basically all EV's besides Tesla's).
Rivian EVSE or Tesla EVSE on a 60A circuit will charge either vehicle at up to 48A. The only advantage to the Rivian for a Rivian is that the logos match and it probably interfaces more smoothly with the Rivian App. The Tesla, OTOH, will probably have, when they release the new firmware (OTA) greater flexibility WRT to load sharing, billing, scheduling etc. but that's moot for most of us.


The cords are pretty long. Even my mobile charger cord for my Model 3 is like 20' long? So there probably won't be an issue with length. If there is though, can you always get an extension cord. Just make sure it's from a quality company since we don't want any fires starting from cheap materials.
The manufacturers deprecate the use of extension cords on either the mains side or the vehicle side. Extension cords are sold for the vehicle side for J1772 but not for Tesla but you can extend Tesla too on the vehicle side with J1772 to Tesla adaptors. Don't do it.
 

ajdelange

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This is an issue for me. I only have 50 Amps. So I either have to use the included portable charger or install the Rivian branded charger and down rate it to 35-38 Amps.
You can install it and comission it for a 50A circuit in which case it will allow the truck to take up to 40A. Or you can install a 14-50R and plug in EVSE that allows the car to take 40A.
 

SeaGeo

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I second what most people have noted. One thing I personally wouldn't sweat is pushing your amperage as high as possible if it's going to be inconvenient or incur large costs. For example, if you have 200 amp service, but are only using 60 of it, then go wild. But if you have say... 100 amp service and are using 60 of it right now, I wouldn't upgrade your service just to fit in another 60 amp circuit. I say that because you're (probably) generally going to charge overnight, and you won't need to charge 0 to 100% overnight unless you have an extreme situation. Even assuming need to charge from 20% to 80% of the R1T overnight routinely, that's 135 kWh*0.60. AC charging is roughly 90% to 95% efficient, so that'd take about 90 kWh of energy. A 32 amp (7.68 kw) EVSE would take 12 hours, and a 48 amp (11.5 kw) would take 8 hours.

One nuance is that your EVSE can use 80% of the circuit. So you need a 60 amp circuit for a 48 amp EVSE, and a 50 amp circuit for a 40 amp EVSE, etc.

From a feature standpoint, if you're looking at two cars, you may want to consider being able to share a single circuit. There is a Grizzl-e coming out that has two handles and manages it on the EVSE itself. My understanding is some EVSE manufacturers like Enelx with the juicebox do that via software with multiple EVSE installed on the same circuit. Not really an issue if you have plenty of service power and room in your panel, but if you are limited by either, it's an option to make charging multiple cars a little easier.
https://grizzl-e.com/grizzl-e-duo/
https://support-emobility.enelx.com/hc/en-us/articles/360002651411-What-is-Load-Sharing-
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