FAQ: Home Tesla charging infrastructure Q&A

[brucet999]

Thank you so much for a detailed and comprehensive presentation.

In my neighborhood of 1965 tract houses, there are a number of different SE panels, including some Zinsco as well as Pushmatic Bulldog, which you might want to add to your reference to Federal Pacific Electric and Zinsco as having a bad reputation for failures.

I'm lucky in that my house got a Square D panel. :smile:

 

[FlasherZ]

Thank you so much for a detailed and comprehensive presentation.

In my neighborhood of 1965 tract houses, there are a number of different SE panels, including some Zinsco as well as Pushmatic Bulldog, which you might want to add to your reference to Federal Pacific Electric and Zinsco as having a bad reputation for failures.

I'm lucky in that my house got a Square D panel. :smile:

Yeah, the Pushmatics get problematic when they're old, they won't turn on or off properly. The good news is that, while they may be a PITA to turn on and off, they're still relatively safe compared to those other two.

I'm a big fan of Square D QO panels (the thinner, 3/4" Square D, not Homeline) and Eaton/Cutler-Hammer CH panels. The industry-standard Siemens/GE/SqD-Homeline/Murray/Bryant/etc. 1" panels are ok, too, but my second choice.

 

[FlasherZ]

I added the new Tesla "find an electrician" program to the FAQ.

 

[DarrenHD]

I added the new Tesla "find an electrician" program to the FAQ.

Just curious how many watts does charging take when you are plugged into a standard outlet? And is it pretty much continuous draw all night (if you are charging overnight) ?

If I was to use a 220V outlet (for example my clothes dryer uses that) I know it can pull upto about 7,700 watts continuously when the dryer is on high. How long would it take to fully charge at 7,700 watts?

Electricity rates aren't exactly cheap in Ontario. off-peak rates are 20 cents per Kwh 7 pm to 7 am. Just trying to figure out how much it add to my electricity bill if I was to charge 3-4 times per week overnight using a standard 110v outlet.

Thanks

 

[FlasherZ]

Just curious how many watts does charging take when you are plugged into a standard outlet? And is it pretty much continuous draw all night (if you are charging overnight) ?

If I was to use a 220V outlet (for example my clothes dryer uses that) I know it can pull upto about 7,700 watts continuously when the dryer is on high. How long would it take to fully charge at 7,700 watts?

Electricity rates aren't exactly cheap in Ontario. off-peak rates are 20 cents per Kwh 7 pm to 7 am. Just trying to figure out how much it add to my electricity bill if I was to charge 3-4 times per week overnight using a standard 110v outlet.

Thanks

A standard, 120V/15A outlet (from which the Tesla can charge at 120V/12A) will draw 1,440W. It will be a continuous load all night. It will add between 2-3 miles of range for each hour it is plugged in.

If you were to use a 240V/30A outlet (typical dryer outlet), the car will draw 24A continuously, or 5,760W. From completely empty, the continuous load will last just over 10 hours. If you were to install the Tesla-recommended NEMA 14-50 outlet, the car will draw 40A continuously, or 9,600W. From completely empty, the continuous load will last about 8 hours.

The car is far more efficient when you use a 240V outlet.

Tesla has a calculator located here:
Tesla Charging | Tesla Motors

It will tell you how long you will have to charge at 120V/12A vs. 240V/40A vs. 240V/80A based on how much you drive on average.

 

[mknox]

Electricity rates aren't exactly cheap in Ontario. off-peak rates are 20 cents per Kwh 7 pm to 7 am. Just trying to figure out how much it add to my electricity bill if I was to charge 3-4 times per week overnight using a standard 110v outlet.

You really need to think about it a bit differently than you would a gasoline car and treat it a bit more how you would use a cell phone. You will find that you should plug it in at every opportunity, and for sure every night that it's parked in your garage or driveway. So rather than a complete (near) empty to (near) full charge every so often, you'll be giving it incremental amounts more frequently.

I've been keeping detailed energy usage info on my Model S for over two years now. I have a dedicated meter on my home outlet and track all of my away from home energy use as well. I'm averaging 446 Wh/mi on my car. This is a calculated number and not what the car's displays show, because the car does not account for the total energy input. That works out to 277 Wh/km, and is reflective of year round usage. The numbers are higher in winter and lower in summer for obvious reasons.

Let's say you drive 1,000 km. That would be 1,000 * 277 = 277,000 Wh or 277 kWh of electricity. At my off peak rate of 21.17 cents, that would come to $58.64 to drive that far. If you use 6 cents per km, that will give you a pretty good idea of how much your electricity bill will go up if you do all of your charging at home and during off peak hours.

Hope this helps.

 

[DarrenHD]

You really need to think about it a bit differently than you would a gasoline car and treat it a bit more how you would use a cell phone. You will find that you should plug it in at every opportunity, and for sure every night that it's parked in your garage or driveway. So rather than a complete (near) empty to (near) full charge every so often, you'll be giving it incremental amounts more frequently.

I've been keeping detailed energy usage info on my Model S for over two years now. I have a dedicated meter on my home outlet and track all of my away from home energy use as well. I'm averaging 446 Wh/mi on my car. This is a calculated number and not what the car's displays show, because the car does not account for the total energy input. That works out to 277 Wh/km, and is reflective of year round usage. The numbers are higher in winter and lower in summer for obvious reasons.

Let's say you drive 1,000 km. That would be 1,000 * 277 = 277,000 Wh or 277 kWh of electricity. At my off peak rate of 21.17 cents, that would come to $58.64 to drive that far. If you use 6 cents per km, that will give you a pretty good idea of how much your electricity bill will go up if you do all of your charging at home and during off peak hours.

Hope this helps.

Thanks that helps alot. Right now per month in my home we use about 500-600 kWh of electricity, the bill comes to about $80 dollars after all taxes. So if I was to drive 1000km per month which would add on average (based on your numbers) another 277 kWh of electricity usage, that may add another $35-$40 dollars or so to my electricity bill. To gas up (depending on what type of car you have) for 1000km it would likely be more than $35-$40 dollars (unless I may have a smart car or efficient small diesel or something)....which I don't...right now I have a Nissan Maxima which takes about $60 dollars to fill the tank of which I get about 500km of city driving (more if highway). So I guess I would be ahead using electricity, unless I had an ultra efficient gas/diesel car.

Anyway, I don't drive 1000km per month, although if I had a model S I may Lol!

Thanks for the info.

- - - Updated - - -

A standard, 120V/15A outlet (from which the Tesla can charge at 120V/12A) will draw 1,440W. It will be a continuous load all night. It will add between 2-3 miles of range for each hour it is plugged in.

If you were to use a 240V/30A outlet (typical dryer outlet), the car will draw 24A continuously, or 5,760W. From completely empty, the continuous load will last just over 10 hours. If you were to install the Tesla-recommended NEMA 14-50 outlet, the car will draw 40A continuously, or 9,600W. From completely empty, the continuous load will last about 8 hours.

The car is far more efficient when you use a 240V outlet.

Tesla has a calculator located here:
Tesla Charging | Tesla Motors

It will tell you how long you will have to charge at 120V/12A vs. 240V/40A vs. 240V/80A based on how much you drive on average.

Thank you very much that is helpful. I would for sure want to charge in off-peak hours (7 am to 7 pm and weekends/holidays) in my area. Unfortunately the closest supercharger location from my house is about a 30 minute drive on the highway. If there was one really close to my house that would have been awesome, but my understanding is that the supercharger network is to facilitate long distance travel and they aren't really supposed to be close to your residence. I guess if you had one close you would be super lucky Based on Tesla' supercharger map out to 2016 they aren't planning on putting one in my city I did email them to suggest it though. Doubt it will happen but had to try anyway

Thanks for the info!

 

[davewill]

Nice deal on an adapter for TT-30

FYI, I found a nice deal on a 14-50 to TT-30 adapter that's actually wired correctly for EVSE use (and if it isn't it looks like I could re-wire it):



Conntek 30A 125-Volt RV/Generator Plug TT-30P to 50-Amp Electric Vehicle Adapter Cord for Tesla $24.99
I can't buy the parts for that price. I haven't actually received mine yet, and I'll report on it as soon as I do.


Pair it with this:

Camco 55223 15M/30F AMP PowerGrip Adapter $6.90


and you've got the two main 120v plugs covered. It may be that I will need to get/make a TT30 to 5-25 adapter that has some cord length to it so the adapter can lay on the ground...or I can just use a short extension cord.

 

[HankLloydRight]

FYI, I found a nice deal on a 14-50 to TT-30 adapter that's actually wired correctly for EVSE use (and if it isn't it looks like I could re-wire it):



Conntek 30A 125-Volt RV/Generator Plug TT-30P to 50-Amp Electric Vehicle Adapter Cord for Tesla $24.99
I can't buy the parts for that price. I haven't actually received mine yet, and I'll report on it as soon as I do.

You actually can get the parts for *slightly* less and make your own 6foot adapter. But it's nice to have a pre-made, compact unit like above.

- - - Updated - - -

I also made a 4foot NEMA 14-30 adapter for about the same price:

 

[davewill]

You actually can get the parts for *slightly* less and make your own 6foot adapter. But it's nice to have a pre-made, compact unit like above.

-- 10-30 picture --

- - - Updated - - -

I also made a 4foot NEMA 14-30 adapter for about the same price:

-- 14-30 picture --

The adapter is for a TT-30 (120v 30a seen at RV Parks) and costs a good bit more than that. The standard dryer outlets, like you are showing, are pretty cheap to make since the dryer cords are sold in large quantities. For the 14-30, I just choose to remove the neutral pin from my 14-50 plug rather than carry another adapter.

 

[HankLloydRight]

Ok, how about using the end of one of these?

Amazon.com : Conntek 14340 RV Pigtail Adapter RV 30 Amp Male Plug To 15/20 Amp U.S Female Connector : Rv Power Cord : Patio, Lawn Garden

 

[davewill]

Ok, how about using the end of one of these?

Amazon.com : Conntek 14340 RV Pigtail Adapter RV 30 Amp Male Plug To 15/20 Amp U.S Female Connector : Rv Power Cord : Patio, Lawn Garden

Sorry, what would this be for? It's the wrong sex on both ends to replace the $7 adapter.

 

[HankLloydRight]

Isn't the male end on both the same? I'm saying chop off the female end, and put on the 14-50 female end.

eta: or do the same thing with this cable: 30 Amp Male RV Plug with Handle to NEMA 5 15R Female 6742 | eBay

I'm just saying, the parts are out there and easy to find to build whatever adapter you want. That's all.

 

[davewill]

Isn't the male end on both the same? I'm saying chop off the female end, and put on the 14-50 female end.

eta: or do the same thing with this cable: 30 Amp Male RV Plug with Handle to NEMA 5 15R Female 6742 | eBay

Oh. The wire is too small since it's built for 15a instead of 30a. The first one you posted is a 20a adapter, better but still not right, and it would cost more than the one I posted did.

The best you could probably do would be buying this one:
Amazon.com: Camco 55185 PowerGrip 30M/50F AMP 18 Dogbone Electrical Adapter with Handles 3750W/125V: Automotive

then chop off the 14-50r because it's wired wrong for EV charging and replace it with another one. But you won't save anything.

 

[FlasherZ]

Tonight I added a question on the orientation of the 14-50 receptacle.

 

[P85_DA]

Flasher what issues if any would I have by leaving the HPWC cable coiled up during charge? I have short distance from wall to car and I leave the cable coiled for most part ...I do recall seeing somewhere here you said wasn't good idea ... My HPWC is set for full 100a but I charge at 56a...thanks in advance

 

[FlasherZ]

Flasher what issues if any would I have by leaving the HPWC cable coiled up during charge? I have short distance from wall to car and I leave the cable coiled for most part ...I do recall seeing somewhere here you said wasn't good idea ... My HPWC is set for full 100a but I charge at 56a...thanks in advance

Most of the time you won't see an issue on an HPWC, because the cable's thickness prevents many tight coils from being made. Long extension cords that are coiled tightly can concentrate heat.

 

[FlasherZ]

I added a question of whether the HPWC can be plug-and-cord connected at the 50A setting, following a reply from Tesla.

Spoiler: NEC and Tesla's instructions as published currently permit this, confirmed by several AHJ's. However, Tesla is concerned about the practice and may amend the installation instructions to require permanent wiring methods, which would be required per NEC 110.3.

 

[mknox]

I added a question of whether the HPWC can be plug-and-cord connected at the 50A setting, following a reply from Tesla.

Spoiler: NEC and Tesla's instructions as published currently permit this, confirmed by several AHJ's. However, Tesla is concerned about the practice and may amend the installation instructions to require permanent wiring methods, which would be required per NEC 110.3.

What is the concern, exactly? Other EVSE manufacturers offer their equipment in both hard-wired and plug connected such as this AeroVironment unit:

 

[FlasherZ]

Here is the specific quote:

For this particular situation, I would be worried about someone falling into the NEMA 14-50 pigtail and yanking it out of the Wall Connector terminal connections, leaving bare wire exposed and connected to a 240 volt / 40 amp power source. It’s Tesla’s intention for the Wall Connector to be a hardwired device in its current form.

My take: if a proper cord connector/clamp was used, and the connections were torqued properly, that it would be extremely difficult to tug the cord out of the HPWC, and it would be like any other cord (RV cord, welder cord, etc.). In fact, I would be more concerned with tools causing damage to the cord loop on the wall than I would to their specific concern.

The biggest limitation, IMO, is the 12" limit on the length of cord attached to the device: that doesn't give much room.