Electrician on His Way

[RG-M3]

I've got a guy I know who's coming out to check me get 240V to my garage. My garage/shop is behind the house, so it's going to be 100ft of copper just to start.

My question is: is there any advantage to using a "dedicated" Tesla wall charger? I was planning on putting in the welding plug, as I have a welder, and just using my standard charger with the proper end (which I have already).

I've been living with 120V for almost a year and I'm pretty sure anything will be much better.

Thanks

 

[Trekker_]

I've got a guy I know who's coming out to check me get 240V to my garage. My garage/shop is behind the house, so it's going to be 100ft of copper just to start.

My question is: is there any advantage to using a "dedicated" Tesla wall charger? I was planning on putting in the welding plug, as I have a welder, and just using my standard charger with the proper end (which I have already).

I've been living with 120V for almost a year and I'm pretty sure anything will be much better.

Thanks

Max amperage using the mobile charger is 50 32 amps at 240v with the right plug which is about 30 miles per hour of charge, much better than 110 volt. Maximum charge rate on the wall connector is 44 miles per hour, which is even better, but does that matter to you for the extra money? Also depends on your car, I believe the SR and LR only charge at a max of 30 mph no matter what anyways(might just be the SR). The performance gets up to the 44 with the wall connector. If you have lived with 110 volt charging this entire time, either option will be leaps and bounds better

I have also read and seen some evidence that the wall connector is MUCH more efficient (about 10% or so) than the mobile charger. How long would it take to make up the cost difference? Depends on your cost per kWh and how much you charge

EDIT: before anyone says it, yes nomenclature blah blah. As a general contractor, it really doesn't matter if you say 110, 115, or 120, everyone knows what you mean. All my electricians say something different. All my estimating programs call it 110v not 120v so thats what I default to.
Also may be inconsistencies in max amperage, but the MPH charged is right. There are even inconsistencies on teslas website. In one spot it says the mobile connectors charges a max of 3 mph.

 

[RayK]

Yes, anything is better than 120V charging. If it were me, and I had the need for a welder as well as EV charging, I would install a HPWC, a 14-50 (or 14-60) outlet and a transfer switch to select between the two. I doubt you would be using a welder at the same time you charge your car but a transfer switch would guarantee that both are not operating at the same time. Keep your mobile connector in your car, along with a good assortment of plug (NEMA) adapters. The HPWC can use up to 48A, your mobile connector only 32A.

This is the route I'm planning for my own garage. I'm going with a 14-50 outlet because my daughter has an RV that I believe can use it when she's here. However, the location I've selected inside my garage is right behind and below my electric service panel so it's only a couple of feet of wires.

 

[jjrandorin]

Max amperage using the mobile charger is 50 amps at 240v with the right plug which is about 30 miles per hour of charge, much better than 110 volt. Maximum charge rate on the wall connector is 44 miles per hour, which is even better, but does that matter to you for the extra money? Also depends on your car, I believe the SR and LR only charge at a max of 30 mph no matter what anyways(might just be the SR). The performance gets up to the 44 with the wall connector. If you have lived with 110 volt charging this entire time, either option will be leaps and bounds better

The SR and SR+ charge at a maximum of 32 amps (on a 40 amp circuit), while the LR AWD / P can charge at 48amps (on a 60 amp circuit). I agree with you 100% on the rest. I have a model 3P with a 60amp circuit, and a wall connector, and while I am glad I have it, never once in 2.5 years have I "needed" the difference in charging speed between 44 miles an hour, and even something like 20 miles an hour.

I will also admit that part of why I got the wall connector was aesthetics... I like how it looks "finished". Nothing wrong with wanting something because you like how it looks, but there is also nothing wrong with using the included mobile connector (nothing at all).

OP, just ensure that you tell the electrician that you are wanting a continuous load. A welder isnt a continuous load, and car charging is. Sometimes people try to say "I want a plug for a welder" because they are afraid of paying extra because "its for a tesla", but I think its good for your electrician to know that its for car charging, so they can ensure they size the wire / circuit accordingly. Continuous load can only use 80% of the circuit rated amps, which is why, to charge at 48amps, you need a 60amp circuit (for a continuous load).

 

[Frank99]

This is just my humble opinion.

The Mobile Connector and the HPWC will, for all practical purposes, charge at the same rate - plug in at night, car will be fully charged by morning. There are a few people who might benefit from the higher power charging available from the HPWC, but for most it's simply not necessary. But it does look cool.

Now, as for costs - Installing a Welding outlet is cheaper than installing an EV outlet, which is cheaper than installing an HPWC. For a welding outlet, I don't believe that you need a $100 GFCI circuit breaker. For an EV outlet, you do. An HPWC saves the cost of the GFCI (it's already built in), and qualifies for a partial tax credit for installing EV Charging equipment.

If you want to leave the Mobile Connector in the car for emergencies, it's about the same price to buy a second MC and install a GFCI as it is to buy an HPWC and get the tax credit. If you're OK with leaving your MC plugged in rather carrying it with you, it's significantly cheaper to just use the MC in a 14-50 (or 6-50 if you're really strapped for cash) outlet.

 

[Gauss Guzzler]

How have you been welding all this time?

Sounds like 14-50 on a 50A non-GFCI circuit would be ideal for you. Easy enough to swap with the welder and the (unused) neutral wire could become valuable in the future if you want to convert it to a subpanel someday.

 

[ucmndd]

I have also read and seen some evidence that the wall connector is MUCH more efficient (about 10% or so) than the mobile charger.

I find this really hard to believe. Can you share what you’ve seen/read?

 

[RogerMc]

I find this really hard to believe. Can you share what you’ve seen/read?

I'm also interested. I'm getting about 95% efficiency with a mobile charger on 240V / 32A. Can't imagine the wall connector doing much better.

120V / 5A I get about 55% efficiency.

 

[Trekker_]

I find this really hard to believe. Can you share what you’ve seen/read?

It's on this forum, I don't have the threads saved. There was a thread where people were comparing charging rate vs power to wall connector. Off the top of my head, the mobile charger at 110v was about 84% efficient, 220v was about 88% and wall connector was about 98%. may not be exactly correct numbers but should be close to was I saw. 110 vs 220 makes complete sense. Higher voltage does less work for same amount of power. The difference between wall connector vs mobile was slightly different in average efficiency but with the faster charging time it made a large difference because over time it made a bigger difference

 

[Trekker_]

I'm also interested. I'm getting about 95% efficiency with a mobile charger on 240V / 32A. Can't imagine the wall connector doing much better.

120V / 5A I get about 55% efficiency.

There was a difference in efficiency between gen 1 and gen 2 wall connectors. Not sure of exact numbers. Trying to remember an old thread here. I just know the wall connector WAS more efficient, by how much i am not 100% sure. It made a fairly large difference though when done out on paper.

 

[RayK]

Maybe this thread?

Model 3 Charging Efficiency

Tesla is the worst EV manufacturer that I'm aware of here. All other EVs that I'm aware of use a negligible amount of energy when off and you can let the car sit for months without seeing more than a few % of the charge lost. Tesla is also the most interactive car. It is a trade-off.

teslamotorsclub.com

 

[RG-M3]

Thanks for all the advice. We were planning on a 60 amp connection for it, sounds like it should run the welder and /or the car with no problems. The welder is at my shop, but it would be nice to use it at home. I think I'll start with the welder plug and if needed in the future, I can always add the tesla wall charger (haven't finished drywalling the garage yet).

I have a SR+, so it sounds like the welding plug might be max out what it can do anyways...

I'm hoping to tap into the A/C which already has a 70AMP wire running to it. As long as I don't use the 2 at the same time, should be fine, and that's really what he's coming to check out.

Thanks again

 

[Gauss Guzzler]

Oh if you already have a 70A circuit there you can just slap a little load center in line and then branch it out to whatever you want. Your AC probably doesn't have a neutral line so you'd be limited to 240V branches but the total rated amperage of all the branches can greatly exceed 70A so you could have the 70A subpanel feeding a 70A air conditioner plus 60A welder and 50A EV outlet thru a little 6-space panel.

There are special exceptions for "welding" outlets which allow a much higher breaker rating than would otherwise be safe for the circuit (e.g. 50A outlet with AWG6 on a 70A breaker) but for safe car charging you should use a properly rated (50A) breaker because of the extra strain/risk of continuous use, particularly overnight.

70A seems like a lot for an air conditioner. Especially in Canada. Especially in a garage. Must be quite the facility!

 

[RG-M3]

Oh if you already have a 70A circuit there you can just slap a little load center in line and then branch it out to whatever you want. Your AC probably doesn't have a neutral line so you'd be limited to 240V branches but the total rated amperage of all the branches can greatly exceed 70A so you could have the 70A subpanel feeding a 70A air conditioner plus 60A welder and 50A EV outlet thru a little 6-space panel.

There are special exceptions for "welding" outlets which allow a much higher breaker rating than would otherwise be safe for the circuit (e.g. 50A outlet with AWG6 on a 70A breaker) but for safe car charging you should use a properly rated (50A) breaker because of the extra strain/risk of continuous use, particularly overnight.

70A seems like a lot for an air conditioner. Especially in Canada. Especially in a garage. Must be quite the facility!

Sorry, the a/c is outside, for the house, but if I can patch into it there instead of in the basement panel, saves me drilling into the house... Does that make sense.

 

[RG-M3]

New "wrinkle" in the plans. My electrical provider is offering $350 off the cost of a wall Level 2 charger. They pay nothing towards a 240 wall outlet. Is it worth spending the $700 on the Telsa wall charger to get $350 back?

Arghhhh....

 

[Gauss Guzzler]

Sounds like a good deal to me. The wall charger is nice and you'd get to keep the portable charger handy for trips to the cabin or wherever. Plus the wall charger is cheaper to install than an outlet since you don't need the outlet, cover, cord hook, wall bracket, or GFCI breaker.

As long as there's a place where you can mount a subpanel and have full access to the AC wiring I believe it should be fine to branch out from there. Note that there's usually no slack in the wires so you likely can't simply cut and splice a panel in - you may need to install a new length of wire to reach the AC as the original will end up a few inches too short by the time it's routed thru the subpanel. This can be a hassle if the wire is stapled to interior studs and whatnot.

 

[Rocky_H]

I have also read and seen some evidence that the wall connector is MUCH more efficient (about 10% or so) than the mobile charger.

That's definitely not true.

It's on this forum, I don't have the threads saved. There was a thread where people were comparing charging rate vs power to wall connector. Off the top of my head, the mobile charger at 110v was about 84% efficient, 220v was about 88% and wall connector was about 98%. may not be exactly correct numbers but should be close to was I saw. 110 vs 220 makes complete sense. Higher voltage does less work for same amount of power. The difference between wall connector vs mobile was slightly different in average efficiency but with the faster charging time it made a large difference because over time it made a bigger difference

Oh. That has nothing to do with wall versus mobile connector types. That is because it's comparing vastly different power levels. At the same power level, like if both are on a 30A circuit, there will be almost no perceptible difference in efficiency. That big difference in efficiency you read about is because there is about a third of a kilowatt of power just consumed by running the charging process. The dinky little 120V outlet is so little power, that about a fourth of it is lost just going to overhead. If you have 5X that much power, the overhead loss because less noticeable, and it is more efficient.

We were planning on a 60 amp connection for it, sounds like it should run the welder and /or the car with no problems.

Eh, well, except that if you are directly using a 60A circuit, there's no really an appropriate outlet type you could use. You would need to run that to a subpanel or something to split out a smaller circuit if you want to do an outlet.

I'm hoping to tap into the A/C which already has a 70AMP wire running to it. As long as I don't use the 2 at the same time, should be fine, and that's really what he's coming to check out.

You can't share on the physical same circuit, though, so hopefully you mean (again) some kind of subpanel to split this somehow.