Not installing 240V at home

[stevezzzz]

Which makes me wonder:

I wired my garage with two, separate 50 amp circuits and 14-50 outlets, because when I moved in here I already had a Roadster and was anticipating the Model S. But since I traded in my R for the S, I'm wondering: is is possible to somehow combine the two circuits to power a HPWC? This is mostly an idle question, since I don't really need to charge at more than 40amps, but you never know...

 

[dtich]

or try a double throw switch similar to the following:

Hubbell Wiring Device-Kellems HBL1388 Switch, 2 Pole, 30 A

mount near your car charger receptacle, then you can switch to the air con when you're not charging and vice versa.. limit the tesla to 30A if necessary for rating.

might work...

 

[FlasherZ]

Which makes me wonder:

I wired my garage with two, separate 50 amp circuits and 14-50 outlets, because when I moved in here I already had a Roadster and was anticipating the Model S. But since I traded in my R for the S, I'm wondering: is is possible to somehow combine the two circuits to power a HPWC? This is mostly an idle question, since I don't really need to charge at more than 40amps, but you never know...

As a permanent install? NEC 310.10(H) governs this. Only conductors of 1/0 and larger are permitted to be paralleled, except for some control cases -- so, no, not to code.

That said, if you were going to violate code, it will work, but you want to make sure that the circuit lengths are the same, it's the same wire, the same raceways, etc. so that the load will be balanced across them.

 

[stevezzzz]

Thanks for the info, FlasherZ. Like I said, it's not something I'll likely want to do. Probably more likely is the scenario where there ends up being another new Tesla parked next to my S, each plugged into its own 14-50 outlet.

 

[Robert.Boston]

My issue is that running power from my house to my parking area would require going under a brick terrace, through a granite retaining wall, and across 30' of landscaped gardens and paths. If I were staying for five years, I'd do it. I'm not, so I'm not. Charging at the office every day, for free, should work for the time being.

 

[RichardM]

Tim,

The J1772 adapter is locked to the charging port while the car is locked. If someone presses the button on the charging cable handle it stops charging and permits disconnection of the J1772 plug from the adapter.

Larry

Not mine. If my car is locked and charging, it does not respond when the charging cable handle button is pressed. It ignores the button press and continues to charge. If the car is unlocked, it will stop charging when I press that button. But not if the car is locked.

 

[jomo25]

Not mine. If my car is locked and charging, it does not respond when the charging cable handle button is pressed. It ignores the button press and continues to charge. If the car is unlocked, it will stop charging when I press that button. But not if the car is locked.

??? I think the point of Larry's comment is that someone can disconnect the J1772 plug (the one from the public charge station) from the adapter at any time. The adapter will be locked to the car, but it doesnt stop someone from disrupting your charging.

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Just so you know, people who actually have the car are seeing more like 2.5 miles of range per hour of charge than the advertised 5 for a 120v plug. 100 miles will take around 40 hours.

So, is there a similar "underestimation" of charging times with a Blink station? I.e. if I read the charge calculator right on the Tesla page, it estimates about 20 miles of range per hour of charging from a 240V/24A outlet, which I think is about what the Blink stations would put out. So, is it really like 10-15 miles instead of 20?

 

[ggr]

??? I think the point of Larry's comment is that someone can disconnect the J1772 plug (the one from the public charge station) from the adapter at any time. The adapter will be locked to the car, but it doesnt stop someone from disrupting your charging.

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So, is there a similar "underestimation" of charging times with a Blink station? I.e. if I read the charge calculator right on the Tesla page, it estimates about 20 miles of range per hour of charging from a 240V/24A outlet, which I think is about what the Blink stations would put out. So, is it really like 10-15 miles instead of 20?

At work, we have Blinks with 208V, 30A, and I use 18 mph to guesstimate charging time (standard mode).

 

[Vger]

Concerning estimation, remember that P = V X A. The voltage matters! At commercial charge stations, the voltage is often 208V nominal, but can be at low as 200V or even lower (I have seen 195V once).

Concerning Tim's situation, consider putting in a 14-30 outlet, rather than 14-50. You need to get an additional adapter from Tesla, but that is a small thing. You can draw 24A @ (hopefully) 240V from a 14-30, and that will get you your 100 mi. overnight, and not stress your home wiring as much. Even running a new line would be much cheaper at 30A versus 50A.

 

[jomo25]

At work, we have Blinks with 208V, 30A, and I use 18 mph to guesstimate charging time (standard mode).

Cool, thanks. I understand P = VA, but how much of that P translates to miles is the fuzzy piece of the puzzle. And based on the 2.5 mi of range for the 120V line stated earlier, I wonder if there was a similar loss at the higher V and A's. But 18 mi/hr is only 10% less than the official statement of 20, close enough that factors like environment temperature, driving style, etc. can account for the difference.

 

[adiggs]

Cool, thanks. I understand P = VA, but how much of that P translates to miles is the fuzzy piece of the puzzle. And based on the 2.5 mi of range for the 120V line stated earlier, I wonder if there was a similar loss at the higher V and A's. But 18 mi/hr is only 10% less than the official statement of 20, close enough that factors like environment temperature, driving style, etc. can account for the difference.

My brief time in the Model S test drive - it appeared that around 3 miles per Kwh (or 333 Wh/mile) is a reasonable number to use for estimating the rate at which electricity gets consumed. On an 85 Kw pack, that's about 255 miles, so it's the right ballpark.

If you're working with a 200V line at 24 Amps, then you're accumulating charge at about 4.8Kw/hr, or about 14 mile/hr. In my completely non-electrician way, this is why I conclude having a 240V outlet at whatever Amps it will draw. Even at low amps, the watts and therefore miles/hr recharged gets to a decent level.

I'm planning to use a 40A / 14-50 for charging, not because I'll use anywhere near the mileage that can recharge on a daily basis, but so that when I do need the mileage, it won't be a thing getting it. I also was able to get the outlet installed cheaply and easily - no tunneling through the landscaping and under walls, so it was a painles decision to make.

 

[jomo25]

My brief time in the Model S test drive - it appeared that around 3 miles per Kwh (or 333 Wh/mile) is a reasonable number to use for estimating the rate at which electricity gets consumed. On an 85 Kw pack, that's about 255 miles, so it's the right ballpark.

If you're working with a 200V line at 24 Amps, then you're accumulating charge at about 4.8Kw/hr, or about 14 mile/hr. In my completely non-electrician way, this is why I conclude having a 240V outlet at whatever Amps it will draw. Even at low amps, the watts and therefore miles/hr recharged gets to a decent level.

I'm planning to use a 40A / 14-50 for charging, not because I'll use anywhere near the mileage that can recharge on a daily basis, but so that when I do need the mileage, it won't be a thing getting it. I also was able to get the outlet installed cheaply and easily - no tunneling through the landscaping and under walls, so it was a painles decision to make.

Well, if I had my own home and garage, then yes, 14-50 or even 14-30 would be the logical thing to do. And I would. But living in a highrise condo with a shared underground garage and a slow moving HOA board, I have to look at other options. I have 2 Blink stations a 5 minute walk and another 2 a 10 minute walk from my condo. I have used them for my Volt on weekends (though much less since they switched to the new cost model - for a Volt, its the equiv of $4/gal gas, for the Model S, it would be about $2/gal comparison).

So, my thought is, I could use those stations while I continue to wrestle with my HOA board to get a shared solution or allow me to install my own station at my spaces in the garage. And at those costs and relative convenience, I could do it comfrotably for a while if need be. Especially with 200+ mi of range, it would allow me to just do one long charge session weekly based on my driving habits normally.

 

[Raven5000]

I don't get it. You guys are spending a lot of money on the car over 50k but can't afford a couple of grand to install the right outlet. Just fork up the dough. Not trying be disrespectful or anything but it just seems kind of odd you didn't plan out all the cost. It should only cost I would think 3k at the most, which just a small fraction of the car price.

 

[Larry Chanin]

Tim,

The J1772 adapter is locked to the charging port while the car is locked. If someone presses the button on the charging cable handle it stops charging and permits disconnection of the J1772 plug from the adapter.

Larry

Not mine. If my car is locked and charging, it does not respond when the charging cable handle button is pressed. It ignores the button press and continues to charge. If the car is unlocked, it will stop charging when I press that button. But not if the car is locked.

??? I think the point of Larry's comment is that someone can disconnect the J1772 plug (the one from the public charge station) from the adapter at any time. The adapter will be locked to the car, but it doesnt stop someone from disrupting your charging.

Yes, we are not discussing charging with a High Power Wall Connector where the cable is locked to the charging port until the owner unlocks the car. We are discussing charging at a public J1772 charger. On the public charger the charging handle has a button which when pressed stops charging. Anyone can press that button, stop charging and disconnect the charging cable even though the J1772 adapter remains locked to the charging port.

Larry

 

[brianman]

My brief time in the Model S test drive - it appeared that around 3 miles per Kwh (or 333 Wh/mile) is a reasonable number to use for estimating the rate at which electricity gets consumed. On an 85 Kw pack, that's about 255 miles, so it's the right ballpark.

Just another data point...
I've averaged 410 Wh/mile for the first 596 miles. I've hypermiled about 10x more than I've floored it. But most of the time I just drive.

 

[GSP]

...... As long as I don't run the AC unit in the room above the garage while I charge, they can put one in. Same-day service from my local electrician, so I can pull the trigger on that if I end up feeling the need (which I know will be day 1 because I'll probably be driving this thing like crazy...)

Charging at 240 V will be more efficient than 120 V. This will make it more than twice as fast at the same amperage, and lower your electric bill. As others have pointed out, 120 V may not be fast enough for some of your high milage days.

I would install a 30 A, 240 V outlet, and limit usage to 15 A, or even less. That would be provide 10 mph charging, which should be more than enough for overnight charging, and also let you run the A/C and other loads on your 40 A circuit. The more efficient charging would probably pay for the material needed to install the plug!

You are buying an awesome, but expensive, car. Why not take full advantage of the convenience of 240 V home charging?

GSP

 

[rbmartin]

Charging at 240 V will be more efficient than 120 V. This will make it more than twice as fast at the same amperage, and lower your electric bill.

You pay for KWh, not amp-hours, so I don't see how charging at 240V would save you any money, unless you have TOU rates and can move more of your charge time off-peak. That said, I agree that there's nothing like the freedom of never having to stop to charge. I would consider the 120V charging option for emergency use only. (OTOH, I can't envision a scenario where twin chargers would be particularly beneficial. 10KW charging is "just right" IMO).

I would go ahead and get a 14-50 or other 240V outlet installed in the garage and just dial the charge current back in the car to whatever your circuit can handle. You will be able to easily cut your charge time by a half or a fourth without doing a major rework of your electrical service.

 

[mnx]

A roadster owner measured the usage at various charging rates. 40A charging on the roadster (@ 240V) turned out to be the most efficient. Also like you mentioned when charging more quickly you can do all you charging on off peak hours.

You pay for KWh, not amp-hours, so I don't see how charging at 240V would save you any money, unless you have TOU rates and can move more of your charge time off-peak. That said, I agree that there's nothing like the freedom of never having to stop to charge. I would consider the 120V charging option for emergency use only. (OTOH, I can't envision a scenario where twin chargers would be particularly beneficial. 10KW charging is "just right" IMO).

I would go ahead and get a 14-50 or other 240V outlet installed in the garage and just dial the charge current back in the car to whatever your circuit can handle. You will be able to easily cut your charge time by a half or a fourth without doing a major rework of your electrical service.