What benefit does a wall charger offer vs. cable alone?

[MBCTex]

When we built our house 10 years ago I had a Tesla Model S on order so I had the builder put in a dedicated 40 amp circuit for charging with 240V outlet in the garage. I never bought a Tesla wall charger, I just plugged the cable my Tesla came with directly into 240V outlet and that's how I charge. I still have my Tesla (replaced it two years ago actually) and now I have an R1S coming for my wife shortly. There's only the one 240V outlet so we'll have to share it, probably charging on alternate nights when we're both home. I've been assuming I would just unplug my Tesla cable and she could plug in her Rivian cable on her nights, and vice versa. It would probably be more convenient to install a wall charger that had adapters for both, but I'm trying to decide if it's worth the expense. Here are my questions I'm hoping someone can answer:

1) Would a wall charger (from Rivian, Tesla, or a third party) charge the vehicles any faster than the cables alone? As I said it's a 40 amp circuit so my Tesla currently charges at 32 amps. I don't see how a wall charger could charge any faster unless I installed a 50 amp or larger circuit (which I don't plan to do). Or is there something about a wall chargers that enables faster charging from the same circuit than the charging cable alone?

2) If I did get a wall charger, is there any reason I couldn't use one of the third party chargers available on Amazon (such as this one). Not only is it half the price of the Tesla Universal Wall Charger, but it comes in a plug in version that doesn't need to be hardwired so I wouldn't need an electrician to install it.

3) If a wall charger won't be any faster, can I just use my Tesla cable to charge my Rivian (with the appropriate J112 adapter) or vice versa to avoid having to swap cables every night? The Tesla cable has an electronic unit inline in the cable and I admit I have no idea what it does, or whether it would cause a problem or simply not work at all if I tried using it on a Rivian. Not sure if the Rivian cable has a similar issue or not.

Any info from the technically-inclined folks on this forum would be greatly appreciated. Thanks in advance!

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[Donald Stanfield]

The only real benefit will be based on the duty cycles of the outlet. Plugging and unplugging repeatedly will wear the outlet out and could cause a short. Some people here recommended certain ones that were industrial grade but I'm not sure which ones those are. Other than that getting a charger isn't any more beneficial for you if you aren't going to upsize the wiring and amperage to make it worth installing a charger.

 

[Redmond Chad]

1) If you aren't going to upgrade the line and breaker, then no, a wall-mount won't charge any faster - 32A is all you can draw from a 40A circuit. (And for most residential use, 32A is fast enough to replace a day's miles overnight). 40A is as fast as you can get with anything (wall-mount or not) that plugs in to an outlet. 48A is currently the limit for most hardwire units, but they can go higher - a decade ago I had an 80A charger installed on a 100A circuit. Few people can spare that much capacity, or need it, so cars generally aren't being built with on-board equipment to handle it. (As vehicles and their batteries get bigger, this may change some).

2) Sure, any charger should work. I wouldn't make price my only criteria, though. Places like evchargingstations.com rate them on several criteria. Given that you already have an outlet, getting one that plugs in rather than being hard-wired makes sense. (Though as Donald noted, that is only if you are generally going to leave it plugged in. If you are going to plug and unplug every day, you should get a stationary unit for the wall that is separate from the mobile unit. It could still be a mobile connector; just leave it plugged in).

3) Yes, you can charge a Rivian from a Tesla charger with a ~$100 adapter. That's what I was doing at my old house. There are several discussions about different adapters on these forums; HERE is the adapter that I happen to use.

You are describing a case where you already have an outlet, and wonder if there's any benefit to switching to a wall-mount (and/or hardwired) unit. For the case you described, I would say no.

The main advantages to a hardwired wall-mount unit show up when you are installing somewhere that doesn't already have an outlet. You don't need a GFCI breaker (which is quite a bit more than non-GFCI), you don't need cable/charger management for the mobile charger, you don't need the outlet itself, the installation fees are slightly lower, and you don't need a neutral wire (which can be expensive if you are running a long line). You can (though you don't have to) get more capacity; and if installed correctly it could be a little safer. I just moved to a new house; I initially considered 14-50 outlets for future flexibility, but after looking in to all the details I ordered two Tesla chargers (one universal, one regular) and next week I'll have an electrician install them.

I also had two Tesla wall chargers installed at my last house, but that was mostly because Tesla gave them to me for free as referral bonuses. The house before that had one 14-50 with a wall-mount EVSE plugged in to it, and one 80A hardwire wall-mount on a 100A circuit (which was complete overkill; but the house had 400A electrical service, and I happened to have a car that could take 80A, and there were far fewer EVSEs to choose from back then).

 

[MBCTex]

This great info, and very helpful. Thank you! I will look into getting an adapter so we don't have to plug and unplug our mobile connectors and can just leave my Tesla one plugged in and share it. But I'll also check out that review site you listed and if I can find a quality, plug-in wall mount unit for not too much money maybe it's worth it just for aesthetics. Appreciate the quick responses!

 

[boise_mountain_biker]

If you want to get 1 wall charger with both J1772 and NACS charging ports, consider the newly released Tesla Universal Wall charger. It has a J1772 sleeve adapter built in along with a NACS port so you can it for both the Rivian and Tesla (my use case scenario as well--its's quite convenient). Since you have a wall socket for 240V, it should be a relatively easy conversion to a hard wire wall charger with minimal work (assuming you keep the 40A breaker and 32A usable current). If you needed to move the charger somewhere else (instead of where the 240V socket is), you'll need to get an in-wall junction box to replace the 240V socket location, then extend the wiring--a relatively easy process.

The biggest advantage of adding a wall charger as another poster said, would be that there would be no wear/tear of the 240V socket from plugging/unplugging the 2 mobile chargers that you have. I think for your use case, I would just get a wall charger for ease and less fuss down the road.

Depending on your existing wiring, you may be able to go to a higher amperage on your breaker (but that is for an electrician to decide or you can use an online calculator for distance/wire gauge needed). 48A (60A breaker with suitable wiring) vs your current 32A (40A breaker) is 50% faster charging, and again, depending on your use case, you may just keep what you have currently setup.

Most chargers have a maximum output charge amperage (48A for instance with a 60A breaker), but they can be throttled down to a lower rate at initial provisioning (like your 32A setup with a 40A breaker). One thing to note on the Tesal Unversal Wall charger is during provisioning, make sure you set it for all cars for ease (3 options: all cars, Teslas only, or certain Teslas (up to 10, added by VIN--ideal if the charger is outside and you don't want a random person using it).

For a review of the above Tesla Universal Wal charger, you can take a look at my original post:

https://www.rivianforums.com/forum/...and-nacs-best-available-single-charger.20640/

 

[godfodder0901]

This great info, and very helpful. Thank you! I will look into getting an adapter so we don't have to plug and unplug our mobile connectors and can just leave my Tesla one plugged in and share it. But I'll also check out that review site you listed and if I can find a quality, plug-in wall mount unit for not too much money maybe it's worth it just for aesthetics. Appreciate the quick responses!

Also keep in mind that your new R1 already comes with a mobile charger (technically an EV not a charger) . Don't bother buying a wall mount EVSE unless you upgrade the circuit and hard wire it.

 

[Electrified Outdoors]

Some knowledge and excellent advice here. Your wife will love R1S.

I always recommend a hard wired unit for a permanent home charging setup. It eliminated possible failure point. I have seen plugs and outlets melt over the yesrs. They also charge faster.

We have two Tesla wall connectors in our garage which share a 60amp allocation. So one can charge st 48 or if both are plugged and charging they get 30 amps each.

For load calcs it only counts as a single 60 amp load even though we have each on its own 60 amp circuit. With two EV and one charger it might be possible you can get both vehicles charged adequately when needed... especially with the mobile unit being limited to 32amps.

My two cents.

 

[SparkyR1t]

A lot of good advice in the responses. You can use the portable cord set that came with the truck forever it is just a bit slower as it is limited to 32 amps by the outlet and circuit. Plan on checking the connections to the outlet periodically and possibly replacing the outlet every so often as it is the wear/weak point. If you get a chance to upgrade to a 60 amp circuit the wall mounted wall connectors are faster and will last longer but only if you want to charge faster. Enjoy the vehicle

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