Advice on Home Charging Upgrade

[sdorn]

I ordered my first Tesla last week (P100D ), and am thinking about my charging setup in my garage.

I currently have a J1772 EVSE for my Leaf that ouputs 7.2kW on a 40 amp circuit breaker. I can't go higher than a 45 amp circuit breaker without having to upgrade my whole electrical box ($$$$), so as far as I can tell my options are as follows:

• Keep my current setup and just use the J1772 adapter to charge the Model S on my existing EVSE. Based on the manual for my EVSE (confirmed by the Tesla home charging consultants), that would add range at the rate of about 22 miles/hr of charging.

or

• Upgrade the circuit breaker to a 45 amp circuit and install a Tesla Wall Mount which can be set to recognize a 45 amp circuit breaker. Tesla's charging consultant tells me that this would give me 8.6kW and about 26 miles/hr of charging. In order to do this I will need to hire an electrician to upgrade the circuit breaker and install the Tesla Wall Mount, so probably about $750 - $900 including the cost of the circuit breaker and wall mount and labor for the installation.

Are there any better options I am not thinking about? Does anyone think the additional 4 miles/hr of charging I would gain by installing the Tesla Wall Mount is worth the additional cost?

 

[andrewket]

Can you find 5 more amps? If you can get to 50A, install a 14-50 outlet and use the UMC that comes with the car.

 

[sdorn]

Can you find 5 more amps? If you can get to 50A, install a 14-50 outlet and use the UMC that comes with the car.

No, 45 amps is the most I can do according to the electrician. Going to 50 amps would require upgrading my electrical box and running a new #6 wire (they used #8 for my current setup) from my basement to my garage (about 50 feet). The electrical box upgrade and rewiring would be about $4,000.

 

[sdorn]

Can you find 5 more amps? If you can get to 50A, install a 14-50 outlet and use the UMC that comes with the car.

I was wondering what would happen if I installed the 14-50 outlet on a 45 amp circuit breaker and used the UMC. Would the car try and pull too much power and overload the circuit, or would it adapt to the current available?

 

[mahroni]

install the 50 amp circuit. charge it at night while you are sleeping and mostly nothing is on inside the house. you are not going to pop the breaker. i think you need to get a second opinion from another electrician. i have a 200 amp panel for my 2300 sq ft home and easily installed the 50 amp breaker, I am also waiting for the electrician to come back to change it to a 60 amp breaker so i can use the high powered wall connector. A few years ago i changed out all the lights in my home to LED and my electrician told me that most of my breakers are only drawing about 2 amps each with all lights on...

 

[BigAirHarper]

The car would try and pull the full 40A but u need 20% overhead on electric vehicle charging. So for 40A u need 50A breaker.

 

[sdorn]

install the 50 amp circuit. charge it at night while you are sleeping and mostly nothing is on inside the house. you are not going to pop the breaker. i think you need to get a second opinion from another electrician. i have a 200 amp panel for my 2300 sq ft home and easily installed the 50 amp breaker, I am also waiting for the electrician to come back to change it to a 60 amp breaker so i can use the high powered wall connector. A few years ago i changed out all the lights in my home to LED and my electrician told me that most of my breakers are only drawing about 2 amps each with all lights on...

I might try having another electrician look at the electrical boxes. The electrician I had come out looked at the boxes I have (two of them) and at the breakers already installed and said they were both maxed out and upgrading to a 50 amp circuit breaker would require upgrading the main box. He wasn't trying to sell me on doing that though, he was basically telling me it wasn't worth doing because of how expensive it would be.

I do have a bunch of LED light bulbs though, and the ones that aren't LED are CFLs. There aren't any incandescent bulbs left in my house I don't think.

Even if I am able to stick a 50 amp circuit breaker in the electrical box I will have to upgrade the wiring from #8 to #6 to pass code. That in and of itself will be close to $1,000 because of the distance it has to be run.

 

[mblakele]

Does anyone think the additional 4 miles/hr of charging I would gain by installing the Tesla Wall Mount is worth the additional cost?

How much do you expect to drive? Charging at 22 mph for 8 hr will net you about 175 RM. That would be more than enough for me, so I'd leave it alone. But circumstances vary.

 

[gregd]

If you can replace the #8 wire with #6 at a reasonable cost (consider contributing the manual labor yourself instead of paying the electrician to do it), then the electrician really should be able to up the breaker to 50A and put in the 14-50 socket. I would challenge the need for the panel upgrade. You're not adding 50A, you're only adding 10, and using the supplied UMC will offset some of the added cost by not needing a new EVSE.

All that said, I've been using a 30A dryer plug (so, 24A 5.7kw charging rate) for my Roadster for nearly 2 years, and never had a problem with not enough time for an overnight charge. You'll have a 1.75x bigger battery than I do, but already have 1.25x the charging rate. I'd see how it goes with what you currently have, then assess the need for the upgrades once you have some real usage data. Maybe it will be ok (recall you also have Super Charger access, which I don't), or maybe the 45A alternative will be sufficient.

 

[miimura]

Personally, I would change nothing. Get the car and see how much of an inconvenience you find using the J1772 adapter every night on your existing EVSE. If you find that is too annoying, get a HPWC and set it for the same 40A breaker you already have. This allows you to maximize your charging without touching the wiring, breaker or panel upgrade. Using the UMC would drop you down from 32A (40A breaker setting on the HPWC) to 24A (30A adapter on UMC). If you find that you want to charge faster, then talk to another electrician to find a creative way to install a bigger circuit. However, I doubt you will find many situations where the difference between 32A and 40A charging would make a difference and the cost to go to 48A (60A breaker) or even higher may be prohibitively expensive for the benefit you would get.

 

[auger]

Keep what you have, or least, try it first. Not worth the hassle for a few mph . . .

 

[WannabeOwner]

about 26 miles/hr of charging

Sounds fine to me. Depends on your driving pattern of course, but arriving home below 10%, or charging above 90%, is a rare thing - particularly needing to charge to 100% from below 10%, so if you can do 80% in a night I reckon that is good enough. Most "nights" are more than 8 hours - get home by 6PM and not have to leave until 6AM.

We do have weekends where I want Max Battery, and I also want Minimum Cost and thus want to use Off Peak rate as much as possible (that's a 7 hour slot during the night over here) so I charge to 100% the night before (and set off immediately) so that the following night I have 10% less charging to need to achieve. (if you can charge at work then on a Friday you could charge to 100% and come home with max possible to allow easy charging to 100% on Friday night on the occasions when you need it)

 

[GSP]

As suggested by others, I would try using your existing 30 Amp EVSE with your J1772 adapter for a few weeks and see how it goes. The 7.2 kW charging rate should be plenty, as long as you don't have a 200 mi/day commute, or need to charge in a 4 hour long super off-peak window.

If using the adapter is not convenient enough, two inexpensive options would be:

1) buy a second J1772 adapter. Keep one in the car, and the other attached to your existing EVSE.

2) install a 14-50 outlet in place of your EVSE, keeping your #8 wire and 40 A breaker. Tesla sells a 14-50 adapter in Canada that limits charging to 32 A, instead of the usual 40 A. Have your electrician check to see if 32 A is OK with the #8 wire. If so, buy the special Canadian 14-50 UMC adapter. You may have to call an Ontario service center to get it. The rest of Canada may still use the normal 40 A adapter. Using this adapter instead of just lowering the current on your touchscreen will insure the car will not try to pull the full 40 A after a software update or glitch.

The former has advantages of being able to charge visitors non-Tesla EVs by removing the adapter, and also being able to keep your UMC in the car all of the time instead of having to remember to pack it for road trips.

The latter has the advantage of having the charging door release button on the UMC's plug, so you don't have to use your fob or the touchscreen to open the car's charge port.

Personally, I would do option 1.

GSP

 

[mikeash]

I also support the advice to just keep your current charger. If you want to keep a J1772 adapter permanently on the charger and another one in the car, you can get a spare from Tesla for $95.

Tesla's wall connector supports a variety of circuit ratings. It supports anywhere from 15A to 50A with 5A granularity (and beyond 50A with 10A granularity), so you could also get one of those and set it for 45A, or less if you prefer. (That's the circuit rating, and it will automatically give the car the appropriate 80% of it. When set for 45A, it will allow the car to draw 36A.)

Another option would be to install a NEMA 14-30 outlet and use Tesla's official 14-30 adapter. That will allow you to charge at 24A, for about 19MPH charging.

I wouldn't worry too much about charging speed. Even with the 14-30, you should be ready to go in the morning after plugging in the previous evening.

 

[Rocky_H]

Yeah, it's not worth it to change what you've got. 7kW is plenty for overnight at home charging, but I would second (fourth?) the suggestion to get a spare J1772 adapter to keep on your charge cable for convenience.

 

[sdorn]

Yeah, it's not worth it to change what you've got. 7kW is plenty for overnight at home charging, but I would second (fourth?) the suggestion to get a spare J1772 adapter to keep on your charge cable for convenience.

That seems like the most sensible idea. With respect to opening the charge port, the Tesla salesperson showed me that you could open the charge port by just touching the corner where it opens with your finger. He didn't use the fob or the touch screen to do it. Is that a new feature, or just a not very well advertised feature?

I already have to open the charge port on my Leaf from the key fob or from inside the car, so no big deal if I have to keep doing that.

 

[AndreSF]

The device you keep referring to as Tesla Wall Mount is called wall connector Other than that, I agree with several others that recommended just keeping existing setup.
Push-to-open charging port is available on new-ish cars.
I think there is some useful advice in this video on how to use J1772 adapter:

 

[Rocky_H]

That seems like the most sensible idea. With respect to opening the charge port, the Tesla salesperson showed me that you could open the charge port by just touching the corner where it opens with your finger. He didn't use the fob or the touch screen to do it. Is that a new feature, or just a not very well advertised feature?

I already have to open the charge port on my Leaf from the key fob or from inside the car, so no big deal if I have to keep doing that.

The push-to-open charge port I think was introduced along with the D dual motor options, which was Fall of 2014. My car from March of 2014 does not have it. I was really glad when they added the feature to be able to unlock the charge port from the key fob. That was a software update that was added after I got my car as well, which is nice if you don't have the hardware necessary for push-to-open.

 

[Diehard7]

My .02 is to keep the current system you have. When I got my MS, Coming first from a Volt then an ELR, I was thinking the same thing you are but I decided to buy the additional J1772 adaptor and keep it attached to my clipper creek at home. Being 100% honest w/myself I realized I wanted to upgrade my HPWC in part to have all Tesla components. When I go in I tend to go all in and I wanted to have the magic charge port door trick occur because it's just cool! In order to still feed my need to upgrade and drink even more of the cool-aid, I've decided to wait until I take delivery of the model 3 for my wife. When I do I'll replace the clipper creek and give it to my sister in law who has pre-ordered a 3 or my mother in law who when I visit I can charge at her home.
Good luck in your decision.

 

[slappy]

The breakers in your box don't drive capacity, save for physical space constraints. So you could have 100A service and have 50 50A breakers in the box and be fine, what drives capacity of your service is the amperage you're actually using concurrently. You can do the math relatively simply, but a couple HVAC units, electric water heater, and a dryer plus a 50A EV charger could be pushing your 100A (assuming that's your service level).

Also, remember breakers protect the wire, and the breaker flips to keep the wire from overheating and causing a fire, so you can't just swap the 40A breaker for a 50A one. I'd also recommend against just putting a 14-50 on your existing #8 gauge circuit. It's against code but also if you sell the house the buyer might try to connect a 50A device to your out-of-spec circuit. The 14-50 assumes 50A and also a mix of 240 and 120V service, it would be like using a USB plug for 120 VAC. You may know the deal, but woe unto whoever unknowingly plugs their iPhone into your "special" plug.

You also can't "get by" with #8, there are specific rules (Google the NEC if you need an insomnia cure) and wire size tables that drive this stuff. It's not rocket science, but it's there for good reason.