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Successfully Home Charging on 110V 15A

FlyinLow

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Feb 5, 2018
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While getting estimates for adapting our household electrical panel to handle additional breakers and considering the cost differences between the HPWC and NEMA 14-50 or 30 outlets we have been successfully charging using only the 110V 15A outlet in the garage.

Our house has the breaker box on the side opposite the garage, about 100 feet away. The estimates we have gotten include the Tesla site survey design. The gentleman doing the actual survey was knowledgeable and thorough. The designs coming back from Palo Alto, CA are unnecessarily expensive.

A local electrical contractor has been much more specific about the costs of components affecting the overall price of each option. The HPWC would need a much larger gauge wire, where a NEMA wall outlet requires smaller wires, due to the smaller current.

Bottom line: for the past month we have been using the MS85 every day for all our normal errands and commute. For trips beyond 30 miles away we stop by to grab a 20 minute charge since the SuCs surrounding Pittsburgh, PA are on the way and never crowded.

From research here on TMC data shows that a 240V, 25A charge rate is the most efficient. When finding that data it opened up the door to considering the NEMA 30A outlet, which will charge at a max continuous rate of 24A (80% rated capacity). I am usually one to overbuild things to prevent overheating and provide for expansion in the future. Since we're not certain of how much longer we will be in our current house, spending thousands on electrical upgrades isn't making sense. Realtors we've consulted have said that sadly electric car friendly or adding solar are not reasons our house will increase in value where we live North of Pittsburgh. In fact, we were told our house could be harder to sell with these modifications.

Any one else using only the UMC to charge from a 15A outlet only? I get about 3 mi per hour rate of charge on 110V-15A. The car is plugged in between 14 and 16 hours a night. We do not have tiered rates for electricity unfortunately. 42 miles is enough for the daily commute and a little driving around town.

I find that I'm only taking the UMC with me on longer trips when I travel in the MS every other month or so. Most days it remains in the garage, coiled up and ready for the car to arrive and be plugged back in.

Your Mileage May Vary...
 

gregd

Active Member
Dec 31, 2014
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CM98
Two things I would consider. First is that charging at such a low rate is (as you noted) less efficient, which means that you're using more electricity than you would at a 240 volt / 24 amp rate. So, a bit of money being wasted there. The other thing is that if the battery ever got really cold, the low current available will take a very long time getting things warm enough to do any real charging.

If you can add a 14-30 outlet in the garage, that will be fine. I charged my Roadster for several years by sharing the clothes dryer's 30 amp plug, and never had a problem getting a full charge over night. A 14-50 is better, and can be used by RVs, welders, and other things unrelated to EVs. It's kind of the universal high power outlet these days. Very common.

Note, I don't believe the Tesla EVSEs require the larger circuits. They can certainly make use of them, but there are switches internally that are set to match the circuit capacity, and will signal the car to not draw more than what is safe. So you don't need to go to the expense of putting in a 100 amp circuit, and all that implies. 30-50 amps is plenty. But check with your electrician on the local electrical code. He/she might not be aware of the internal switches.

And there is no way that any of these will make the house harder to sell, presuming they are installed to code. What is their logic on that?
 
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n2mb_racing

Active Member
Jun 14, 2014
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durham, NC
If you have a dedicated circuit for the 120V 20A with 12awg wires, you can switch it over to a NEMA 6-20 for very little cost. It looks similar to a regular outlet, but delivers 240V @ 20A. That will let you charge at 240V 16A, which gets most of the efficiency gains. That is what I use to charge the Roadster. I use a NEMA 14-50 for the Model S. I didn't have enough capacity in the panel for two NEMA 14-50 outlets.
 
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davewill

Active Member
Feb 5, 2014
1,828
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San Diego, CA, US
I'm sure that a 30a outlet would work just fine. However, I unless putting in a 50a circuit is triggering large extra costs, like having to upgrade a panel, I would just go with that.

If you decide to stick with 120v, take the time and effort to be sure that the outlet and circuit are in good repair, and that you know exactly what plugs/lights share the circuit. Be particularly aware of cheap outlets and stabbed in connections to outlets, which are prone to fail. It's well worth paying an electrician for an hour of his time to be sure.
 

scottm

Legacy account
Jun 13, 2014
3,070
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Canada
If you have a dedicated circuit for the 120V 20A with 12awg wires, you can switch it over to a NEMA 6-20 for very little cost. It looks similar to a regular outlet, but delivers 240V @ 20A. That will let you charge at 240V 16A, which gets most of the efficiency gains. That is what I use to charge the Roadster. I use a NEMA 14-50 for the Model S. I didn't have enough capacity in the panel for two NEMA 14-50 outlets.

Switching over means installing side by side 20A breakers

You would need the Tesla 5-20 adapter head for the UMC charger

And you would need a nema 6-20 to 5-20 conversion cord, from the 6-20 wall receptacle. As it would be irresponsible to put a 5-20 receptacle in the wall with 240 behind it..

Maybe surprising to some the Tesla 5-20 headed UMC can take 240v just as well as 120v

However, yes, you can do all that above and get a bit more than double your charge rate. Without running new wire branch circuit.

If you installd a 15-30 (dryer circuit) instead youd get 4 times your current charge rate. This is a new wire pull from your panel, a dual breaker, new receptacle in garage, Tesla adapter.. if you've got panel room for a new 30a pull, may as well pull 50a and use the fitments for 14-50 UMC to get that out there....

I went the route of whole house panel upgrade 200A with 100A subpanel in garage, and about $8000 later would say it wasn't worth it to have 80A HPWC in the garage because I now seldom use it, or charge at home at all.. times have changed since I started un 2014.
 
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FlyinLow

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Feb 5, 2018
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Lots of good recommendations here. Thank you.
If I’m only going to be in the house for another 12 to 18 months the cost of installation (right now my lowest estimate is $1500 for the NEMA 14-50) will not offset the electricity saved by charging at a higher efficiency.
Our realtor advisor was mostly talking about the solar install, which I thought was a good idea for an all electric house. Apparently people in or moving to Western PA don’t understand solar yet.

I hope this discussion helps others setting up s house or apartment for charging. If I was staying in the house longer I’d for sure be putting in the NEMA 14-50 outlet at least.
 

n2mb_racing

Active Member
Jun 14, 2014
1,133
710
durham, NC
Switching over means installing side by side 20A breakers

You would need the Tesla 5-20 adapter head for the UMC charger

And you would need a nema 6-20 to 5-20 conversion cord, from the 6-20 wall receptacle. As it would be irresponsible to put a 5-20 receptacle in the wall with 240 behind it..

Maybe surprising to some the Tesla 5-20 headed UMC can take 240v just as well as 120v

However, yes, you can do all that above and get a bit more than double your charge rate. Without running new wire branch circuit.

If you installd a 15-30 (dryer circuit) instead youd get 4 times your current charge rate. This is a new wire pull from your panel, a dual breaker, new receptacle in garage, Tesla adapter.. if you've got panel room for a new 30a pull, may as well pull 50a and use the fitments for 14-50 UMC to get that out there....

I went the route of whole house panel upgrade 200A with 100A subpanel in garage, and about $8000 later would say it wasn't worth it to have 80A HPWC in the garage because I now seldom use it, or charge at home at all.. times have changed since I started un 2014.
There's now a 6-20 plug for the new UMC.
 
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brkaus

Well-Known Member
Jul 8, 2014
7,878
6,380
Austin, TX
Lots of good recommendations here. Thank you.
If I’m only going to be in the house for another 12 to 18 months the cost of installation (right now my lowest estimate is $1500 for the NEMA 14-50) will not offset the electricity saved by charging at a higher efficiency.
Our realtor advisor was mostly talking about the solar install, which I thought was a good idea for an all electric house. Apparently people in or moving to Western PA don’t understand solar yet.

I hope this discussion helps others setting up s house or apartment for charging. If I was staying in the house longer I’d for sure be putting in the NEMA 14-50 outlet at least.

If it works for you, nothing wrong with it. Good learning for others too!

I'd be curious what someone would charge for a dedicated 5-20 outlet. Just to see how much of a Tesla/EV upcharge your getting. 5-20 and 6-20 should cost about the same.

You said the breaker box is on the other side of the house. Would it be possible to reach the road from it? Charge parked on the street.
 

Missile Toad

Member
Aug 30, 2016
619
601
Houston
I used a 15A circuit protected outlet for a year here in Houston. I upgraded the GFCI to handle the NEMA 5-20 setting (20A, with 16A continuous). That is enough charge for average daily 40 miles round-trip. As others have stated, cold can be an issue -- but not here in Houston.
 
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scottm

Legacy account
Jun 13, 2014
3,070
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Canada
There's now a 6-20 plug for the new UMC.

I've never seen a 6-20 receptacle in the wild here in Canada... hm.

5-15 common,120v 15A
5-20 now becoming more common, 120v 20A
6-15 old things, on the farm, sump pumps, 240v 15A
6-20 strange bird, 240v 20A

The Tesla 5-20 UMC adapter lets me dial up to 16A, from either 120v or 240v whatever I stuff into it, using adapter such as 6-15 to 5-20.

For a jump up snap on the 15-40 adapter, and have made various adapter plugs to that... lets me dial up to 40A (old UMC). Covers most any plug I'll find around here that is 240v..
 
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FlyinLow

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Feb 5, 2018
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If it works for you, nothing wrong with it. Good learning for others too!

You said the breaker box is on the other side of the house. Would it be possible to reach the road from it? Charge parked on the street.

That’s a great idea I hadn’t considered. Thank you. Unfortunately there’s no access to the panel side of the hose from the road. I know I’m a cheap skate but it looks like we’re moving in a year or so. A nice 14-50 install would be a sunk cost.

Maybe a 6-20 outlet could be installed for a reasonable cost. That would at least get up in the 240V region.

My breaker box is full. Site survey resulted in estimate with a second breaker box required. There is a limit as to how many double circuits can be added to a panel.

After calling the design team in Palo Alto, I found out today they have multiple cost thresholds. Less than ten feet from the breaker box and over ten, up to 100 feet is the first two categories for cable length. It looks like they over estimate to cover additional materials like conduit. The contracts don’t show many details.
 

brkaus

Well-Known Member
Jul 8, 2014
7,878
6,380
Austin, TX
After calling the design team in Palo Alto, I found out today they have multiple cost thresholds. Less than ten feet from the breaker box and over ten, up to 100 feet is the first two categories for cable length. It looks like they over estimate to cover additional materials like conduit. The contracts don’t show many details.

I'd deal with a regular electrician, get a few quotes for your 240v / 20a compressor your buying to put in the garage.. The "design team in Palo Alto" is going to work on generalities.

But as you said, if it works, it works, and its a sunk cost.

I hear you on the over estimation. I paid for 10 ft of wire, conduit, etc. My HPWC is on the back side of the wall from the main box.
 
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Missile Toad

Member
Aug 30, 2016
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601
Houston
I forgot to mention, it cost about $40 in parts, since I already had 12AWG in the wall. (1) GFCI upgrade to 20A & (1) NEMA 5-20 outlet + 20 minutes shopping & 45 minutes doing the install (after shutting down the cct breaker at the panel).

Routine charging begins at 2:20am (gets the high wind generated gird energy here in Texas), and is sufficient for my needs, keeping the charge in this range: 120 - 216 RM, with the median, 'wake-up' charge in the morning at around 201-205.

I used a 15A circuit protected outlet for a year here in Houston. I upgraded the GFCI to handle the NEMA 5-20 setting (20A, with 16A continuous). That is enough charge for average daily 40 miles round-trip. As others have stated, cold can be an issue -- but not here in Houston.
 

Missile Toad

Member
Aug 30, 2016
619
601
Houston
@scottm, how did you find out about the 240v handling capacity of the NEMA 5-20 adapter? See Tesla reference. Incidentally, my S 70D adds Rated Miles at about 4.8 MPH (113v & 16A).

Screen Shot 2018-03-27 at 10.32.53 AM.png

Maybe surprising to some the Tesla 5-20 headed UMC can take 240v just as well as 120v
 

KidDoc

Supporting Member
Aug 6, 2014
348
428
College Station, TX
When I first moved to College Station we rented a home for 6 months so I charged with a plug in the garage. Luckily I also had access to the dryer plug which was 30A if I started to fall behind on charging. I did not have any access to a supercharger. It was a bit annoying but overall worked fine with no crisis events just a few episodes of having to leave the garage door open and dragging the big plug into the utility room after a road trip.

That being said my 40A plug I have in my permanent home is much better!
 

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