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Many questions on home wall charger. Help appreciated.

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,258
9,122
Riverside Co. CA
Hey gang, an update. Talked to the electrician that wired my house and a 20A breaker is a no-go; the wiring is 14 gauge, not 12. BUT, he charges me $80 to install a 220V 40A outlet back-to-back to the breaker box outside the garage, which is the way I want it (not drilling the outside of the house). The outlet would be lower than typical, but not an issue, since the cable would only get unplugged for trips on the car, which are not that often. I asked the guy for a Bryant outlet, but he said his shouldn't be an issue, since it uses bolts to secure wires. So that's exactly how I'd do it :). Oh, and he'd use 6 gauge, to install a Tesla charger in the future, if desired... but he said for safety reasons he'd use 40A breakers. Makes sense, no? If installing a Tesla charger, it'd be a matter of just replacing the breakers for 60A. Anyway, have a few more questions, based on that development:
1. No long-term additional degradation of the battery pack from charging at 32A at 220V rather than 12A at 115? Or is the ideal rate somewhere in-between, and which would it be? If we ever need 32A, we could raise it easily on the screen, right? And no issues leaving car connected all the time if it's 32A, correct? Since we don't need 32A most of the time, might as well try to maximize the life of the battery if it causes no issues for us.
2. To charge the car on its intended spot, I'd need at least 20' cable, and the new ones are only 18'. No big deal, as we can swap places, but my wife could inadvertently hit my car when carrying crap from the trunk of her car to the door, since she'd have to pass next to my car. If I can find an older cable, which I think were 24', any issues with that? I could charge up to 40A, but wouldn't use that. And does the car know at which amps to charge, or you have to tell the screen that? Thanks guys; you've been super helpful. Greatly appreciated :).


No there are no degradation issues charging at 32amp vs 12. Both of those are considered "slow charging". if you are going down the rabbit hole on battery degradation (I suggest you dont, but you may have already done so), when they refer to "fast" charging, its DC charging or supercharging.

All tesla home charging is "slow" charging. There isnt any issues with older tesla connector equipment vs newer equipment. Find and buy whatever one meets your needs as far as cable length.

You will NOT need to "turn down the amps" for any technical reason, if you have your electrician install a dedicated circuit. The car will know what to charge at, as long as you dont use extension cords and such.

I am not trying to be mean, and believe me, I get the excitement, but you are overthinking this. Get your electrician to put in the 40 amp circuit. Plug in either the mobile connector that comes with the car, or another tesla connector you buy, let the car charge at the rate it sets up (which will be 32) and set your charge level to whatever you want to, between 50% and 90% for daily use. Thats pretty much it.
 

comanchepilot

Member
Oct 3, 2017
404
324
SoCal - EAST
It's pretty darn simple to replace a garage dryer or other 240v [or even add a circuit] outlet with the Tesla charger. I bought one for under $300 new in the box on eBay - and its a better EVSE than the current limited one in the car. It's literally $10 in parts. I installed a new circuit in my panel for $150 with parts extra using an electrician who was doing other things in my house - we put in a 50 amp circuit. This way we have 44 set up in the EVSE - and it'll limit it to 40 most times - which is 80% of the demand. Thats a darn fast home charger.

You might already have the bigger wire for a 40A circuit that will get you the customary 32A.

We are 10 miles from a SC in SoCal - which means it's not exactly convenient. Wife charges over night at 9.6c a Kwh. The new Model S Long Range Plus actually costs a little bit less to charge since we lose less charging fewer time - and 345 miles between charges using a daily charging set up - means 3 days between charges commuting 42 miles each way. . . . and she can charge at work - meaning its basically a free car when it comes to actually driving it.

I keep the Tesla supplied EVSE and the J1772 adapter plug in the car - you don't want to lose those or not have them when you need them -
 
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comanchepilot

Member
Oct 3, 2017
404
324
SoCal - EAST
I'm sorry - thoughts on your questions:

1. Is it worth/necessary to pay $500 (plus probably a hefty installation charge) for a home charger, with a supercharger 2 miles away?
Go to the SC at the times of day you would be charging. . . see what the load is. Which dictates how long you would wait most days. We have a SC less than a mile from our Tucson house - and its open virtually 24/7 - so that is a viable option though it will cost much much less to charge it at home -

2. If not, no issues always using a supercharger? Not sure if they are 75kW or 150kW, but can find out.
I have a friend with an X who has free SC for life - he only has 120v at home - so he SC all the time - he just does business calls in the wait. You can use a SC all the time - but if you charge in such a manner as to make Tesla wonder if the vehicle is being used as a taxi - then you have to answer to them about it/.

3. If yes, does it have to be permanently installed if you're going to use 120V? If not, meaning you can take it with you when you travel, how many hours would it take to charge an LR M3 from 30 to 90%?
NO ONE should use 120v. Ever. Unless you hve days to charge it - the current losses are just too darn high.

4. If wall charger needs to be permanently installed, then it'd make sense to hook it up for 220V... but can you do that without having to mess up your house (drilling, etc)? I only have 1 dual outlet in the garage, which I'd still need operational.
Running a new line in conduit is simple - especially if you have a couple of open circuits in the panel. It really isn't that complicated. Try to mount the EVSE into the studs and not the brick or stone side of the garage.

5. If I need to drill, I'd probably install it right behind the electrical panel, which is at the end of my garage, so not a huge deal, but it'd probably cost a pretty penny. Any tips or advice would be greatly appreciated. First EV ever. Thank you.
It's pretty simple - I would mount the EVSE so the cable rests on the ground for most of the travel to the charging port. You should have strain at any of the attachment points for the plug or the wires coming from or to from the unit. Installing a new wire means prob getting the heavy duty 240v 50A soft cable to avoid conduit if its that close - there is a limit on all of this in the electrical code. Drilling to install the EVSE is pretty simple - mark the stud(s) where its going - predrill the holes - then use a socket on the big screw heads - that makes it so much simpler.
 

pjensen

Member
Jul 24, 2020
155
93
Highland Village, Texas
3. If yes, does it have to be permanently installed if you're going to use 120V? If not, meaning you can take it with you when you travel, how many hours would it take to charge an LR M3 from 30 to 90%?
NO ONE should use 120v. Ever. Unless you hve days to charge it - the current losses are just too darn high.

My car charges up at 6 miles per hour (12 amps) from a 120 volt socket in my garage. Since I drive 20 to 30 miles every day, this easily fills up the car over night. I can go several days before recharging the car.

My wife will be buying a Tesla M3 also in a few months. One 120 volt socket in the garage will handle both cars. She will drive less than I do.

I've been using this since September (3 months now) and it absolutely works well.
 
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DaveRZ

Member
Nov 19, 2019
164
219
Murrieta, CA
My wife will be buying a Tesla M3 also in a few months. One 120 volt socket in the garage will handle both cars. She will drive less than I do.

Do you intend to charge them simultaneously? If so, you'll need to turn down the charging rate of each car to 6amps... which is really really slow. But hey, if it works for your needs, right on! Either way, congrats on a multi-EV garage!
 
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pjensen

Member
Jul 24, 2020
155
93
Highland Village, Texas
Do you intend to charge them simultaneously? If so, you'll need to turn down the charging rate of each car to 6amps... which is really really slow. But hey, if it works for your needs, right on! Either way, congrats on a multi-EV garage!

Since I only need to charge my car every 3 to 4 days, she would charge on one of those available days.

Dirt simple. There are 14 hours available every night (plug in at 6pm, unplug at 8am). This gives 84 miles a night. Even if I reduce it by 35% (for subfreezing temperatures), that would be 61 miles a night. That is ridiculous overkill for a 20 to 30 miles a day driving.
 

kadify

Member
Nov 19, 2020
263
105
colorado
This may be a fluke, and I'm totally willing to pass along the info to anyone in CO, but I got an install cost of $721 (including the WC) in my garage. Obviously I hopped on that deal and am getting it installed tomorrow. Hopefully no surprise charges.
 

elptxjc

Member
Dec 15, 2019
752
142
El Paso, TX
No there are no degradation issues charging at 32amp vs 12. I am not trying to be mean, and believe me, I get the excitement, but you are overthinking this.
Great to know the first part; thanks. And no, I wasn't overthinking anything; just trying to understand something new... and I do now. I don't care about battery degradation other than trying to maximize its life, IF it doesn't inconvenience us. It'd be the same to charge at 32 than at 25A, for instance, hence my asking. But since 32A is perfectly fine, I'd leave it alone at that. And decided to do the NEMA 14-50 with 50A breakers, so will never need more than 32A (30 miles/hr) with the mobile cable. Just ordered the 14-50 adapter, plus the cable organizer, so I'm almost ready for the car :). I'm done with this crap. See? Didn't overthink anything. Ha ha. Thanks guys.
 
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Big Earl

bnkwupt
Jul 12, 2017
5,231
9,452
Springfield, VA
I asked the guy for a Bryant outlet, but he said his shouldn't be an issue, since it uses bolts to secure wires. So that's exactly how I'd do it :). Oh, and he'd use 6 gauge, to install a Tesla charger in the future, if desired... but he said for safety reasons he'd use 40A breakers.

Please insist on a Bryant or Hubble brand NEMA 14-50 receptacle. The $15 Leviton from Home Depot us absolute junk.

Good call on the 6 gauge wire to make it future proof and the 40 amp breaker for maximum protection of the expected 32 amp load (a 50 amp breaker would be overkill for the intended load).

As for your comment about needing to swap places with your wife in order to make the cord reach, consider backing the car into the garage.
 

Gasaraki

Active Member
Oct 21, 2019
1,546
1,019
Syracuse, NY
Hey gang, an update. Talked to the electrician that wired my house and a 20A breaker is a no-go; the wiring is 14 gauge, not 12. BUT, he charges me $80 to install a 220V 40A outlet back-to-back to the breaker box outside the garage, which is the way I want it (not drilling the outside of the house). The outlet would be lower than typical, but not an issue, since the cable would only get unplugged for trips on the car, which are not that often. I asked the guy for a Bryant outlet, but he said his shouldn't be an issue, since it uses bolts to secure wires. So that's exactly how I'd do it :). Oh, and he'd use 6 gauge, to install a Tesla charger in the future, if desired... but he said for safety reasons he'd use 40A breakers. Makes sense, no? If installing a Tesla charger, it'd be a matter of just replacing the breakers for 60A. Anyway, have a few more questions, based on that development:
1. No long-term additional degradation of the battery pack from charging at 32A at 220V rather than 12A at 115? Or is the ideal rate somewhere in-between, and which would it be? If we ever need 32A, we could raise it easily on the screen, right? And no issues leaving car connected all the time if it's 32A, correct? Since we don't need 32A most of the time, might as well try to maximize the life of the battery if it causes no issues for us.
2. To charge the car on its intended spot, I'd need at least 20' cable, and the new ones are only 18'. No big deal, as we can swap places, but my wife could inadvertently hit my car when carrying crap from the trunk of her car to the door, since she'd have to pass next to my car. If I can find an older cable, which I think were 24', any issues with that? I could charge up to 40A, but wouldn't use that. And does the car know at which amps to charge, or you have to tell the screen that? Thanks guys; you've been super helpful. Greatly appreciated :).

There's no difference between 32A and 12A charging.
You tell the car how many amps to charge at.
The gen2 Tesla Wall Connector has a longer cable but they don't sell those anymore. You might be able to find it on ebay.
 

kadify

Member
Nov 19, 2020
263
105
colorado
Not sure if it has been mentioned yet but if you get a charger installed before 1/1/21 you can get 30% via a federal rebate. Form 8911 if you didn't know about it.
 
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XLR82XS

D M C
Jul 26, 2019
3,110
1,737
SWFL | Vegas
Your Tesla can pull large amounts of current for long periods of time when charging.

Have your electrician install a 14-50 amp socket near where you want to charge and be done with it.

Charging either off a 120V circuit or exclusively using a Supercharger is inconvenient.

No need for the $500 wall connector, unless you think it looks great and can take advantage of the slightly quicker charging.

You can plug in every night, and have a 90% filled battery every morning.
THIS! (spell corrected electrician for ya ;))
 

pjensen

Member
Jul 24, 2020
155
93
Highland Village, Texas
Dirt simple. There are 14 hours available every night (plug in at 6pm, unplug at 8am). This gives 84 miles a night. Even if I reduce it by 35% (for subfreezing temperatures), that would be 61 miles a night. That is ridiculous overkill for a 20 to 30 miles a day driving.

Ok here is a real life example:

I drove 26 miles yesterday. That was 8 short trips (to work, to a store, home for lunch, out to lowes for some parts, home, work, gym, home).

The car (2020 SR+) energy screen showed that 39.5 miles of energy was consumed. It was a cold 40 degree day here so the heater was running the whole time. Efficiency was 66%.

I plugged in the charger this morning (just for fun). It showed 6 hours and 35 minute charge time. If I had plugged in the car last night at 6pm (when I came home), it would have finished charging by 1 am. The car would sit idle for 7 hours. Note this is a 120 volt wall socket (using the included free charger cable).

Do I really need to upgrade to a faster charge?
 

tga

Supporting Member
Apr 8, 2014
3,882
2,686
New Hampshire
3. If yes, does it have to be permanently installed if you're going to use 120V? If not, meaning you can take it with you when you travel, how many hours would it take to charge an LR M3 from 30 to 90%?
4. If wall charger needs to be permanently installed, then it'd make sense to hook it up for 220V... but can you do that without having to mess up your house (drilling, etc)? I only have 1 dual outlet in the garage, which I'd still need operational.
The Wall Connector isn't spec'ed to run on 120V, anyway (manual says single phase, 200-240V nominal). Since you need to run 2 wires plus ground, there's no point in 120V (hot/neutral) with double the charge time instead of 240V (hot/hot), even if you could.
Those type of outlets are not really built to be plugged/unplugged daily.
Why are you unplugging your UMC daily? Plenty of people plug it in and leave it alone. For months or even years. Unless you know you need it to charge at your destination, you probably don't need it on a road trip (the days of 40A charging at RV parks are long gone).
And since we don't travel often, I'd just pack the cable and put it in the trunk, if we're going on a trip; no need for a second one.
You can take it with you on a trip, but you'll probably learn it's not much more than a security blanket (see above).
Thank you very much. I just checked my circuit, and it's for the 3 garage outlets only... but it only has a 15A breaker. The problem is that one of those outlets is for the garage opener, another for the irrigation box, and the last is open, but I always leave a charger hooked up to the Bullitt there, which can draw up to 5A, so would have to disconnect that one for sure while charging the car. The question is if the opener would trip the breaker when car is charging. If yes, then it's a no-go.
And that's the problem with charging on an existing 120V duplex outlet - it's often shared with other loads. Worse, if you aren't using the first outlet in the circuit, you're pulling lots of power through multiple splices and junctions, which isn't really a great idea. A dedicated outlet is "home run" directly back to the breaker, likely with no splices, just a single contiguous run. The fewer connections, the better (which is one reason why a hardwired wall connector is better than an outlet).
In fact, a 14-50 outlet will probably need a GFCI circuit breaker, which is quite pricey, whereas the wall connector doesn't require one.
If your community is on NEC 2017, an EV charging outlet (14-50 or otherwise) is REQUIRED to have a GFCI breaker (50A = $100). The Wall Connector REQUIRES a regular, non-GFCI breaker (from the manual - "For maximum power output, install a standard double pole 60 amp circuit breaker. Wall Connector includes integrated GFCI protection - do not install a GFCI circuit breaker" - their emphasis, not mine).
Oh, and he'd use 6 gauge, to install a Tesla charger in the future, if desired... but he said for safety reasons he'd use 40A breakers. Makes sense, no? If installing a Tesla charger, it'd be a matter of just replacing the breakers for 60A.
Actually, that depends on the type of wire used. NM-B/Romex (the all-in-one cable) no, THHN/THWN in conduit, yes. The rules say NM-B can only use the 60C rating, which limits you to a 55A circuit. 80% of that is 44A max charge rate. There is no 44A setting for the Wall Connector, so you have to go down to 40A (though still more than 32A). Wire in conduit can use the 75C rating, which is good for a 65A circuit. 80% of that is 52A max charge rate. Again, there is no 52A setting, so that give you 48A max charge rate.
And does the car know at which amps to charge, or you have to tell the screen that? Thanks guys; you've been super helpful. Greatly appreciated :).
All (properly installed) charging stations (UMC, WC, J1772) "know" the size of the circuit (wire & breaker) and communicate that to the car. The car will never go over the limit. You can dial it down, but not up.
 

tga

Supporting Member
Apr 8, 2014
3,882
2,686
New Hampshire
Also, now that Tesla no longer includes a 14-50 adapter, "install a 14-50" is, IMHO, no longer the correct answer for "what outlet should I have?" Rather, the right choice for almost everyone is: "install a 6-50"
  • 14-50 requires a neutral which is not used by the UMC. 6-50 has no neutral. Outlet is cheaper, wire/installation is cheaper (no wasted 6ga neutral)
  • Industrial grade 6-50's are available
  • You have to buy a new UMC adapter anyway
Someone will say "but then you can't plug in your big RV that you might buy someday," or "What if weird uncle Harold wants to park his RV in your driveway for a month" - So what? If you're buying a $100K RV someday, you can add a 14-50 then. The best location for an RV outlet is probably not the same as the best location for a charging outlet, anyway. Nobody I know owns (or plans to own) a monster RV. And do you really want to encourage weird uncle Harold to park his behemoth in your driveway for a month?
 

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