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Supercharger at home

Hi all,

I keep wondering, why does nobody release (or Tesla themselves for that matter) a charger for home use that is built in and uses the Supercharger tech??

I mean, if I have to install a charger for the high power system anyway, why not let me buy a SuperCharger?! Can't be that expensive?

I will try to be a little clearer then...

I don't want 'at least 3-phase 480v / 400A service' in my house and I don't need it.
I want to supercharge the in-car-battery using an in-house-battery with similar capacity and characteristics. If such a battery can deliver 300kW peak to a Tesla-S engine I suppose it can charge another battery with a measly 120kW. And yes, I am aware that I can only re-charge that stationary battery with 10 kW and that it will take 10 hrs to do so. But I don't care because I will only need to do such a supercharge twice a day at most - 10 hours apart.

Would such a solution consisting of : one 85kWh battery, 12 chargingunits and 1 meter of thick cable, be more expansive than a Tesla-S ??!

You can't use those chargers like that. You would need DC-DC converter and those are AC-DC converters. It probably would not cost as much as Model S if you consider only parts needed, but that kind of solution does not exist, so designing and actually building one could well cost you more than Model S. It would not be an easy task.

Of course, stupid me. I missed the DC-DC vs AC-DC converter issue which should have been quite obvious to me. I was not aware that a DC-DC solution for this specific purpose might not exist. But I can imagine that it is not cheap.

In addition to the DC-AC converter, a Supercharger will need a significant Air Conditioner to keep your home battery cool as well as the battery management computer to control the charging protocols.
If mass produced, these could probably become a lot cheaper than a Model S, however, given the limited market, I doubt that enough would be sold to support mass production of such a product. Tesla and its investors have already put the Model S into mass production.
As one of the first Tesla drivers (Roadster in Nov, 2008), I have only really needed the HPWC level of charging a few times, when I had done a lot of driving during the day, then needed to charge quickly in order to go out in the evening. I can't think of any times when I truly needed to go from empty to a full charge in only a few minutes as the Supercharger enables. The HPWC charges at around 60 miles per hour, enabling you to make a 30 mile round trip in the hour it takes to shower, and dress for an evening's festivities. For me, that has always been sufficient but it does call for the dual onboard chargers and HPWC.

E and N;
Is not the Roadster hi-power AC charger called a HPC, and the Model S unit a HPWC? Seems like a useful/necessary distinction to keep in mind.

I think many of you are confused regarding wattage, voltage, current, AC to DC and vice versa. A 500A 3 phase service to a property (although not a real possibility, as services would either be 400A or 600A) is enough to power a small manufacturing plant with multiple motors, large transformers, in addition to lighting and office space. Usually the building size would 15-30,000 sqft. or greater.

I find it unlikely that the 120kW SC is referring to one single charger, as the wire to the car would be between the sizes of 4/0 to 250 MCM copper, much heavier than any soccer mom or business professional is willing to haul to their vehicle and plug in. The 30A/240V home units that most other EV are using only draw 7.2kW maximum (likely around 5.76kW max in reality) from the grid. I am sure that the 120kW number is actually the total draw for all 6 SC units at a charging station not just one. That would mean that each SC would actually only draw 20kW each, which if using 3 phase-480V (600V in Canada), each would draw 25A on the 480VAC side of the charger(19A on the 600VAC side in Canada). Large chargers used for forklifts and the like, have between 15A-30A feeds supplying them if at 480VAC, and 50A at maximum if supplied by 208VAC

Also, to clarify, no residential single detached home would ever be allowed to have a 3 phase supply brought to it, unless it is well over 10000 sqft in size, and would probably have to be using electric heat exclusively to justify the service upgrade. If you are wondering about my math, when dealing with 3 phase systems, voltage x current does not equal watts as it would in single phase equations, you must first multiply the voltage by the root of 3(1.73 approx.) then mutiply that number by the current. ie. 120,000W/(480Vx 1.73)=144.6A, not 120,000W/480V=250A

To put all this in prospective, I would be very surprised if the entire Tesla headquarters(including the assembly plant), which is likely running 480VAC 3 phase, is supplied by more than an 800-1200A service. And they probably have a full SC station fed from that same source.

Brace yourself. An 85kWh battery that half fills in 30 min requires what?

SC is DC charger. So 120kW/480V is correct calculation (assuming charging voltage is 480V). How big grid connection whole SC has depends on how many charging units it has. Power lines are probably in kV area connections, not something you have in houses or small manufacturing plants.

I am referring to the AC supply to the charging unit, which can vary greatly, from 600V 3 phase to 240V single phase. I'm just trying to convey that a SC is possible in a residential environment without needing a 600A service to run the thing, and that a 600A-480V 3 phase service is a ridiculously massive thing to run one battery charger for any size of car.

@Brian H,
Yes, you are right, the home charging station for the Roadster was referred to as the HPC (High Powered Charger), the Model S one is referred to as the HPWC (High Powered Wall Charger).
The max charging current for the Roadster's HPC is actually 70 Amps while the the Model S maxes out at 80 Amps for slightly faster charging. Conceptually, they are about the same and given the Roadster's better efficiency, the charging speed for the Roadster is a bit faster.
At our house, we have a Clipper-Creek CS-90 J-1772 charging station that can charge Leafs, Volts, Roadsters, and Model S (adapters needed for Teslas) at 70 amps.
As I've mentioned, either is more than sufficient for most of our home use over the past 5 years.

Well if the stated charge time on a 240VAC/40A charger for a 85kWh battery is ~9 hours and a the stated charge time for a Supercharger on the same battery is 1.25 hours, the huge improvement in charge has to come from somewhere. The Supercharger chart claims to be 12 times more powerful than 240VAC/40A. (10kW to 120kW). So I would guess thats where the 480VAC/240A came from. If they are charging 7000 laptop battery cells at once, I could understand this sort of load. A random laptop around my house takes in 120VAC and outputs 20VDC/5A. Multiply that by a lot, and there you have it.

Of course I'm just spitballing here :)

What I would think is more realistic (and something I would like to do) is enable a business (or even a group of Tesla owners) to install their own supercharger.

I recall an official source saying that the superchargers cost about 100K each (I may be recalling incorrectly, but that seems realistic). If there are 10 Tesla owners willing to fund, and one of them has access to a commercial property that could be used with sufficient power (for example, an RV park), why not permit them to build their own SC? I would gladly put up 10K to fund a supercharger along I-57 between Chicago and Memphis; maybe I could find 9 others willing to do the same (maybe not). And, a "lite" supercharger at maybe 80kW might be a lot cheaper than 100K.

It is even possible that a business might be willing to build their own and charge for it if they thought it would bring business in for their main business (an RV park located on a main route? shopping center? maybe even chargepoint).

If Tesla permitted (or better, encouraged!!) this, there would be access issues. I doubt that the privately funded chargers would be free and a privately funded charger might be limited to only members of the club that funded such. That doesn't seem to me to be a deal killer issue though; a private supercharger that requires membership or is pay-to-use is better than none.

Given the relatively slow pace of supercharger construction (outside of the East and West coasts), this seems like a better way to incent SC construction especially in more remote areas that are on trafficked routes between cities (and not on the I-80 corridor that Tesla has committed to build out).

I would prefer that Tesla do all the work, but it is clear they cannot, at least not across the entire US, and especially in the midwest and south. Why not permit private industry and wealthy Tesla owners to help out especially where there is a strong need and willing contributors?

Don't get your hopes up. TM is not selling chargers and the control systems, AFAIK. A distraction.


I assume you have filled in the form that Tesla provides at
"How can I help bring a Supercharger to my area?
Contact Tesla with your suggestions here."

It leads you to the following link:

I don't know what Tesla does with these forms but if you have a place in mind and are willing to provide significant material support, I could see how Tesla might be interested.

That can't be good for battery health.

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