mknox
Well-Known Member
Ahhh... a kindred spirit. I don't know why, but it really bugs me every time I hear someone talk about a "110 volt" outlet.
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Neighbor buys Tesla Model S. Neighbor installs HPWC. Neighnor sell Tesla...
- Thread starter ponzu
- Start date
Ahhh... a kindred spirit. I don't know why, but it really bugs me every time I hear someone talk about a "110 volt" outlet.
I think because 110 is half of 220. The brain/typing fingers adjust for the illogicality of 120 (or 115).
I got un update on my neighbor's sit. He does not and did not have HPWC, that was a misunderstanding on my part. He did pay $1500 to pull a new 220v line from the panel to the outside wall nearest driveway, terminating in a 14-50 NEMA outlet. That's what he gave up along with his Model S.
dhanson865
Well-Known Member
Because the actual electricity in America is 120v and 240v. There is no 110v, 115v, or 220v in America.
The earliest documentation for the standardization of 120v in America I can find goes back to around WWII.
Anything you've ever seen in your life marked 110v or 220v in the US is leftovers from nomenclature from the early half of a prior century (the first third of the 1900s still had various utilities providing power at various voltages).
Anything marked 115v is for international trade purposes because that device can be used in 120v countries like the US and 110v countries in other parts of the world.
See Mains electricity by country - Wikipedia for a list of what countries use which voltage.
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Of course there is 220v and 115v in America. 220v is what comes to my electric panel from the utility before it get lowered to what you consider 120v, but my Testla currently charging from a wall outlet is clocking at 115v.
Got it. They require that I switch to Time-of-use in order to get the $500 rebate and to TOU-EV-1, which, in turn, requires that I install a separate meter, to get the $1500. Good to know that these options are there, and perhaps they will be helpful to someone else, but in my calculation the TOU plan hurt me.
Alright, sorry, the current that comes to the house is 240, not 220. 220 is a European memory. But 115 is a fact of life. Not only do I always hear "115" from people discussing charging, but my car says 115 when charging from the wall. I understand it is supposed to be 120, as in half of 240, but it is 115 IRL. Do we know who and how loses me the 5v? I'm happy to be educated. The 12 amps is the same, though, and I believe that's what counts.
mknox
Well-Known Member
In Canada and the US, the nominal residential electricity voltage level is 120/240 volts split phase. There are three conductors (plus ground) consisting of a neutral and two "hot" legs 180 degrees out of phase. Each leg to neutral produces 120 volts and leg to leg produces 240 volts.
This is the "nominal" voltage and it will vary somewhat. Loading on the utility transformer and losses in the conductors can contribute. There are guidelines governing minimum and maximum voltage levels at the service entrance for "normal" and "extreme" operating conditions that utilities must adhere to.
But when referring to these systems, they are to be regarded as "120 volt" or "240 volt".
Interesting, as I don't think I've ever heard someone mention 115v in my entire life!
It's possible yours shows 115v due to loses. Do you have a long wiring run or old outlets? My 14-50 outlet shows 240v before I start charging but normally drops to 232v or so when charging because we have a long wiring run between the main panel and the subpanel.
Butane
Member
You can blame Ohm's Law if you want. Voltage (V) = Current in Amps (I) * resistance in Ohms (R). 100ft of 14awg wiring has a nominal resistance of 253 milliOhms. At 12 amps, that's a voltage drop of .253*12 = 3.0V, and that's just from the breaker to your car. (For 12awg wire, it's a 1.9V drop.) The breaker will have some voltage drop, as will the feeder to your house. A 5% drop in nominal voltage is the max allowed by code for residential uses, so 114V is the minimum. (There are no direct code rules for sizing wires for long distance runs, electricians just have to make sure they don't lose more than 6V at the load based on expected current draw.)
The difference is lost as heat (blame Joule heating) and it's the resistance multiplied by the square of the current. P = I*V = I^2*R. That 3V drop results in 36W of lost power whenever you charge, or about an extra kWh every 28 hours of charging. Put another way, if you used superconductors with no loss, you'd charge about 4% faster.
In my house with overspec'd wiring, I see 249V in the car when plugged in via the HPWC but not drawing any current. It usually falls to 246-248 under 48A load though, depending on whether we're using any other electrically intensive loads at the time.
If all you use the car for is commuting, then no need to change your plan. Otherwise, I'd go for it.
110V charging is crazy slow and supercharging shortens battery life (as per Tesla's own instructions); HPWC is the ideal medium: fast enough to allow you to charge to max overnight for a one-day road trip and slow enough to be gentle on the battery.
The cost of installing a 240V outlet at home is about the same as the cost of installing an HPWC (that's not counting the cost of the HPWC itself, but that's where you neighbor comes in ;-), but the outlet alone limits you to charging through the mobile charger setup and a Gen 2 mobile charger is limited to 32A, so you'd charge at 7.6KW max, whereas the Model 3 charges at 48A (11.5KW) through the HPWC. Charging at home rather than at superchargers will also be *much* cheaper -- your utility probably has special rates for EV charging at certain hours and it's trivial to set up your Model 3 to charge at fixed hours (you plug it in when you return from work, but it does not charge until the programmed period).
BTW, my electrician bill for the HPWC was $500, and I live in Hawaii, where all trade services are ridiculously overpriced. Fortunately for me, the main house electrical panels are all on the outside wall of the garage, so it was a short cable run (4-gauge cable is expensive) and minimal work for an experienced team (about 2 hours for two people, one licensed electrician and one helper). I got quotes from $500 to $1500, however, so shop around ;-)
That's not required -- the install requires a licensed electrician, but anyone can turn off the breaker and disconnect the wires and it takes all of 5mins to do that, even for an HPWC. The electrician cost will be to install the 14-50 or HPWC (same cost, as it will be 4-ga wire in either case, unless the wire run is very long). Plus there is a >50% difference in charging rate (for a Model 3) between the HPWC (48A) and a Gen 2 mobile charger on a 14-50 outlet (30A).
First off, the chances that a neighbor will let you go pull something out of their electrical system, without hiring an electrician is slim to none. You can use 6-gauge wire for a 14-50 (at least in my jurisdiction) as well. A 14-50 outlet will charge at 40 amps, not 30.
Cirrus MS100D
Member
I know a person who had a gorgeous gray + black wheels X 90D and an outdoor HPWC, but the X suddenly disappeared.
He replaced it with a beater Honda.
Because his X got damaged.
In January.
And is still waiting to get repaired and returned
It is possible I made 115v up as far as a standard. I noticed that whenever I say or write 110v, 115v or 120v people tend to understand that I mean something other than 240v, aka "wall outlet", so no one has corrected me until now.
But Tesla is on my side, showing 115v while charging. Long run? It's on the other side of the house form the panel, wired in-wall, I assume (as opposed to via the attic), but daisy chained with at least three other outlets that I know of. One unused on side of house, the other two used for sprinkler timer and house security system. Old outlets? I'ts a 13 year old GFI outlet. Maybe GFI circuitry makes its mark on the curent. BTW, I followed another topic where someone complained that their GFI pops after a short time charging. Mine held up for about 3 hours before I stopped charging, so I think I am okay there.
Here at the office, I am showing 109v (ouch), but still 12/12a. It's the amp that count, right?
BTW, following up on a tip I received earlier, I ascertained that the outlet at work is a 4-20 (the one at home is 4-15 as expected), so I ordered a $35 NEMA 4-20 adapter from Tesla. Their own chart shows 4-15 as being good for charging 3 mi/hr and 4-20 for 4 mi/hr. These might be model S/X numbers, as I seem to be getting 4 or 5 mi/hr from a 4-15 outlet. Of course, all that being an estimate that Tesla assumes is easier for us to process rather than the actual number of kWh it drew in any given hour or charging session. If the 4-20 adapter will help me charge 25% faster for free for about 5 hours a day, I think I will recoup my $35 investment in about a year
Overall, I have to say that the "electric lifestyle", which is what Tesla congratulated me on the beginning of the day before delivery, makes one pay attention to small numbers a lot. It gets to be we know exactly how much we pay per kWh, per mile, per trip. A friend invites you to visit, you estimate a 120 mi roundtrip at $7.50 and say to yourself: that's pretty reasonable, while also thinking: would the said friend consider it reasonable, too, if I plugged in at his house while visiting? In the ICE life, the trip cost 3-4 times more in gas, but the cost was implicit. You gassed up once a week and treated it as the cost of owning the car, while the charging seems to be the cost of driving. I can see where the "electric lifestyle" may not be for everyone. It suits me just fine for the time being.
I can hijack my own thread if I wish, right? The neighbor didn't have an HPWC after all, so that horse was dead before be beat it.
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My cost for charging at home is $0.24 kWh and my cost for charging at a ChargePoint station across the street from work is $0.25 kWh. My cost at work is $0, but limited to about 6 kWh per day. My utility offers plans that allow to pay less at night, but my calculation show that I will lose out as the day rates will go up and that's when we burn most of the energy -- AC and such. There is an EV specific plan, but requires a separate meter, a $2K cost.
At these prices, I believe the basis for my "electric lifestyle" will be the ChargePoint once a week to the tune of about $6 and free charging at work the rest of the week. I don't think I need additional infrastructure at home.
