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installation of plug for charger, and curious about th HPC 2.0

Discussion in 'Model S: Battery & Charging' started by nleggatt, Dec 19, 2011.

  1. nleggatt

    nleggatt Member

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    Ok, two questions in one.

    My house only has 100A breaker on the main braker so the electrician said I might have to run a new conduit from the main line to the braker, which means digging up a new conduit line through my garage as the hydro box is on the outside of my garage. Could I not just connect a second dedicated 100A line to the outside hydro box and to a dedicated braker and charging station on that side of my garage rather than running a new line and redoing all the wiring by the current braker?

    Also, I'm confused about how fast the charging rate is (mph charging) based on various volts and amps... ie: 120v standard plug (not sure amps), and 240V 40Amps or whatever. The reason I ask is because I was reading about the HPC 2.0 and how it needed a second charger on the car to work to get the full use... can I still charge on a 240V 40Amp without the second charger? Will I still be able to charge at typical J1772 outlets with only a single charger?

    I was considering also buying the HPC2.0 charger and installing it at a friends house that is half way between one of the road trips I would probably make a lot, Kamloops area, or having it installed at my brothers place which is along one the routes I'll travel more frequently. Remote fast charging is more important than home fast charging IMO.

    I'm sort of confused by the 100+ different charger types and charge times and 1 or 2 chargers, and HPC2.0 and AMPs etc etc. Hopefully Tesla can streamline this. I don't want to miss buying a second charger only to find I can't use the quick charge stations that Tesla is putting in, or that I can't charge faster than x MPH.
     
  2. Lloyd

    Lloyd Active Member

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    In your situation I'm sure that you will find that 40 amps will serve you fine and likely save you lots of $$. I would not bother installing an HPC.
     
  3. nleggatt

    nleggatt Member

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    What sort of MPH charge is off a 240v 40amp? what about 30amp? there was some concern over what amps I could draw off our current panel, can the car be told to charge at 240v 30amp if need be? Someone should create a form that you put in your volts and amps and battery size and it tells MPG charge or something... lol (or maybe it exists already).
     
  4. VolkerP

    VolkerP EU Model S P-37

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    I second Lloyd. You don't need a HPC 2.0 at home.

    Running a second line to the garage would require to install a second meter, along with additional fixed costs (basic rate) from the utility.

    Any Model S will charge from the "Tesla Supercharger" fast DC charging stations. It is not clear if every battery pack size is capable to absorb the full 90kW, though.
    You only need that second on board charging unit for up to 20kW AC charging, that is at 240V and between 40A and 80A. You can then make use of the HPC 2.0 (up to 80A), the Roadster HPC (with adapter, 70A) and some high power J1772 EVSE (with adapter, up to 75A - e.g. from clipper creek).

    The typical J1772 charging point delivers 30A (e.g. Coulomb) and that is just fine for Model S with one on board charging unit.

    Beware that interoperability with J1772 cannot be taken as granted. There were some issues encountered by roadster owners, as reported by Bonnie here.

    The 110V spare mobile connector is only an emergency / away from home tool. There are reports from Roadster owners that charging your battery only with that (or even with 240V 16A) is detrimental to battery capacity. So go for more amps. You should wire your garage with a NEMA 14-50 socket (40A continuous) or NEMA 14-30 ("dryer socket", good for 24A) and check that enough "unused amps" are available when charging.

    You might find further information helpful to you in these threads:
    How best to prepare before my Model S comes?
    How to design my garage?
     
  5. VolkerP

    VolkerP EU Model S P-37

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    [email protected] is roughly 10kW and charges the 85kWh pack full in <10h. That pack was formerly called "300 miles." So let's round that to 30mph.
    30A is 75% of that, alas 22 mph.

    MPH is independent of battery size, since all Model S will have nearly identical consumption.

    The Roadster can be told to charge in 8A increment steps via its VDMS. With the Tattler, the underlying system's 1A increment steps are available. I expect the Model S to have a similar feature. However, the car identifies the maximum charging current that is coded into the plug adapter. You don't NEED to dial down in order not to blow anything.
     
  6. Doug_G

    Doug_G Lead Moderator

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    You're pretty much stuck upgrading your electrical panel. If Kamloops is anything like Ottawa the power utility will charge an obscene amount to temporarily disconnect the meter (over $1000). Total cost will be over $3000 for sure. Worse if the electrician decides to hose you. I got four quotes, and the highest was over $7000!!!

    So I spent $3000 for the electrical install, and $2000 for the HPC.

    On the other hand, a NEMA 14-50 plug, installed, would have cost me a couple of hundred bucks. The UMC is $1500, and I ended up buying it anyway because I need it for road trips.

    If I had to do it all over again, I wouldn't have bothered with the HPC for my Roadster. I rarely charge at 70A anyway. It's not necessary. 40A is plenty for an overnight charge, even if the car's on fumes (and it almost never is!). At 40A I'm rarely charging more than a couple of hours.

    In my experience, you don't need an HPC at home. You really want an HPC on the highway... but you usually end up with NEMA 14-50 anyway.
     
  7. efxjim

    efxjim Member

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    A good rule of thumb for charging amps vs distance is amps at 240v is a little more than miles added per hour. A 70A HPC will add 60 miles of range in an hour. A 40A charge level will add about 35 miles of range in an hour.
     
  8. Kipernicus

    Kipernicus Model S Res#P1440

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  9. neroden

    neroden Happy Model S Owner

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    First "secret": volts times amps equals watts. :)

    kilowatt = 1000 watts.
    kilowatt hour == energy you get by charging at 1 kilowatt for an hour

    Mind you, I picked all this up from Wikipedia....

    If you know the battery size in kWh, then it's pretty easy to figure out the time to charge to full. We know the battery sizes in kWh -- the big one is 85 kWh.

    (It's not yet clear how many miles per kWh the Tesla Model S will get, and "your mileage will vary", so figuring time to charge for x miles is a bit harder. The estimates are in the ballpark of 0.3 kWh per mile, but they have something like a 30% error margin at this point.)

    You need to know a couple more things. First, a "standard" 120V household outlet in the US is "15 amps" at the breaker. Second, US "240V" is generally 220V, but in some areas it's 208V -- I'll assume 220. Finally the amperage ratings of outlets is *amperage at the breaker* -- the actual deliverable amperage is usually 80% of the amperage at the breaker, so a "240 V 50 amp" socket (NEMA 14-50) delivers 220 V 40 amps reliably, or 8800 watts, or 8.8 kilowatts. Some high-power sockets deliver a larger percentage of the breaker capacity.

    This means, dividing 85 kWh battery by 8.8 kilowatts, it will take about 9 hours 40 minutes to charge the "long range" Tesla from empty to full with a NEMA 14-50.

    It will take 59 hours on an plain ordinary household outlet. (There are also higher powered standard household outlets which are 120V 20 amp with the same sockets -- you can see that this is 120 * 16 = 1920 watts, or 44 hours 17 minutes.)

    The single charger will do 10 kilowatts, so you are limited to that speed of AC charging (DC charging is another matter) if you have only one charger. This is good enough for the NEMA 14-50 or slightly better (you are unlikely to find slightly better anywhere, though). With this, if you plug into an HPC, the rate you'll get will be 8.5 hours to full.

    With two chargers, you can do up to 20 kilowatts. The HPC 2.0 will probably support at least 220V * 90 amp (real, rather than at breaker -- breaker will be at 100 amps for this IIRC), which is 19.8 kilowatts, just short of the 20 kilowatt limit. That's a full charge for the big battery in 4 hours 18 minutes.

    Does that help? I suspect knowing your mileage would help a lot for this computation; you are unlikely to be draining the battery to near-zero in range mode and filling to full for most of your use cases.

    If you frequently make a road trip which (one way) is significantly beyond the range of your car, but not more than *twice* the range of your car, then installing an HPC at the midpoint would be ideal for you. So (assuming a 300 mile range) if you regularly travel to a point about 580 miles away, you want a NEMA 14-50 at home, a NEMA 14-50 at your destination, and an HPC 2.0 right in the middle. 14 hour trip, you can avoid an overnight stay in the middle.

    If your road trips are longer than twice your range with the large battery, you probably want to start staying places over night (because that's getting into too many driving hours per day), or you need fast DC charging. On the other hand, if your road trips are just a little bit over your car's range, so that you just need a "top up", you probably just want a NEMA 14-50 in the middle.
     
  10. Robert.Boston

    Robert.Boston Model S VIN P01536

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    Whether you can get by with the current 100A service depends critically on how much current the rest of your household use draws. At my summer home (100A), the only power draw of note is the electric oven (on a 50A breaker), the refrigerator, and the pumps for fresh and waste water. No A/C, a smattering of lights, nothing big, so I'm comfortable charging at 40A there -- I just need to avoid baking and charging simultaneously! At my main house, that wouldn't work; too many other things that draw, or might draw, power and overload the main breaker.
     
  11. Trnsl8r

    Trnsl8r Blue 85kwh since 12/8/12

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    OK, hope nobody thinks less of me if I pose a possibly really stupid question here. Mind you, I don't know much about electric power. Here goes...

    Observing that the regular 110 outlet is by far the most common in the US, and...
    that they typically are mounted in pairs...

    ... would it be possible to construct a charger for the Model S with two 110 plugins that could harvest the juice out of both plugs and charge a bit faster that way?

    Not something for the home setup, but useful when visiting far-away friends or on road-trips...
     
  12. Lloyd

    Lloyd Active Member

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    Here is where you can order an adapter. Note that you must have two separate circuits on opposite phases.
     
  13. Mycroft

    Mycroft Life happens

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    Yeah, and most homes don't have two separate circuits near each other, much less separate phases.
     
  14. nleggatt

    nleggatt Member

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    Thanks for the info about the charger.

    @Trnsl8r - I was going to ask the same thing, so don't feel bad about the question. Hopefully people here are more open minded than that - hopefully Model-S owners will be known as welcoming approachable people, as well as ones that drive sweet cars!

    In my place I have lots of lights, a few computers, Heat Pump etc. So the amperage will be close. I'll probably install the 40Amp and charge when I can on the full Amp (middle of the night), and then lower amps other times.

    I've read that slow charging (120v) is bad for the battery, but then read that fast charge stations is bad as well. What is the "ideal" charging numbers for the battery health?

    Also, didn't know where to post this, and didn't feel like making a new thread. But here is an article I wrote a month and a bit ago (before reserving my car btw and before asking any questions on the forum). It has some nice photos (might also be a shameless plug for a project I'm working on lol): http://www.emmaactive.com/blog/tesla-model-s-sedan-review-and-photos.html

    I'll post a new one now that I'm more up-to-speed lol
     
  15. qwk

    qwk Model S P2681

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    I think the sweet spot is between 30-40 amps.
     
  16. Todd Burch

    Todd Burch Electron Pilot

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    At 240v (of course).
     
  17. qwk

    qwk Model S P2681

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    Yes, There is no way that you could pull that through a 120 outlet unless you have no breaker and want to start a very quick fire.
     
  18. VolkerP

    VolkerP EU Model S P-37

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    Pulling 40amps is 40amps. The heat dissipation is I²R so same heat for 40amps at either 120V or 240V.
    You are right if you would try to pull the same power from 120V instead of from 240V. That would double the amps.
     
  19. TEG

    TEG TMC Moderator

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    #19 TEG, Dec 21, 2011
    Last edited: Dec 21, 2011
    I think there is more "it depends" going on with what is best / recommended. From what I have read, 120V isn't favored more because it is less efficient. You have a basic overhead in running the charging system, so with only 120V@~15A a noticeable percentage doesn't make it into the battery.

    For higher rates, heat in the cells can be a problem, particularly when charging the top 80-100% of the battery SOC. So, for instance, it might not be good to use "range mode" high kW in Phoenix in the summer, but no big deal in Lake Tahoe in the winter...

    There is also the issue with difficulty in getting circuits above 40A in many houses, because there typically aren't consumer devices using those levels.
    So, 30-40amps is a "sweep spot" in part because of convenience, safety factor for use in extreme charging conditions, and covers the charging overhead with plenty to spare to actually fill the battery.
     
  20. qwk

    qwk Model S P2681

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    I don't know of any 120v outlets that have wire big enough to support a 40 amp draw in the US, do you?
     

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