Supercharger

The Tesla Supercharger provides DC fast charging for properly equipped Tesla vehicles.



[top]Debut

The Tesla Supercharger made its public debut on Monday, September 24th, 2012 at the Tesla Design Studio in Hawthorne, CA.

[top]Features

The Supercharger can charge a Model S from empty to half-full in approximately 30 minutes.

Tesla have pledged to supply power equivalent to the total used for Supercharging from solar sources. In some cases, this is from a Solar Canopy above the charging points. In cases where the Solar Canopy cannot be provided (due to site constraints), Tesla have pledged to offset this from other locations.

The network is free of usage charges "for life", to suitably equipped Tesla vehicles (currently, all Model S 85kWh, and the Model S 60kWh if an additional fee has been paid at the time of purchase).

[top]Network

(See main article Tesla Supercharger locations.)

At launch, 6 locations were available in California.

[top]Technical Details

The supercharger uses the standard Model S charge connector, and uses the same two pins on the connector that normally deliver 240VAC (up to 80A) to instead deliver approximately 365VDC at up to 225A (when charging a 85kWh Model S). Hence when charging an 85kWh Model S the supercharger delivers around 80kW. The Supercharger is specified to deliver up to 120kW for future vehicles that can accept charge at that rate. The capability of the 60kWh Model S is not yet known, but has been stated by Tesla to be less than the 85kWh - on the assumption that it scales in proportion to the battery size, that would suggest approx 150A (55kW).

The rate of charge decreases as the charge progresses. Exact details are not yet known, but it is said to charge rapidly (constant rate?) to 'half' full, and then tail off to a slower rate as it approaches fully charged. One example shows a Model S 85kWh pack at 131 ideal miles (a little under half) still charging at 216A. Charging can be set in the car to 'standard' or 'range' mode. It is believed (but not confirmed) that the behaviour is the same as for normal AC charging: both modes follow the same charge profile up to 90% of full charge, at which point Standard mode stops charging while Range mode carries on to the maximum permitted level.

Superchargers are installed in pairs. Each pair is driven by a stack of standard Model S chargers (ie. the same 10kW charger unit that is installed in the car in single or dual configurations), arranged in groups of 3 such that they can be fed conveniently from 3-phase power. The stack contains either 12 or 9 chargers (for a total of 120 or 90kW) feeding the two charge cables. The power available from the chargers is distributed between the two cables according to demand: if two 85kWh cars, both empty, arrive at the same time then they will receive less than their ideal charging current. Ideal for the 80kWh car is 80kW, so they will get 75% or 56% of their ideal current (depending on number of chargers in the stack) and charge correspondingly more slowly. If the first car has already reached a substantial level of charge, or is a 65kWh model, then it will be drawing less than the maximum and so a greater proportion of the charger's capability can be directed to a newly-arrived car. Reports in early 2013 indicate that this sharing is not adjusted dynamically: if a car is charging at less than full rate because a second car is also present, the charging rate does not automatically rise when that car departs: it is necessary to stop the charge and restart to obtain full power (this may obviously change in future software/hardware revisions).

The smallest sites have just one supercharger stack (ie. charging spots for 2 cars). Larger sites have multiple charger stacks. Some sites appear to have been prepared with the civil engineering (parking places, conduit under the road surface, concrete base for the chargers) for multiple stacks but only equipped with one set of electronics initially. It also appears (eg. from looking at the Folsom site) that adjacent parking spots are not served from the same charger stack. Identifying which slot to pull into for maximum capacity will require further research. More recently, the bays have been labelled with numbers denoting the separate chargers and letters that show the separate stalls on the same charger (1A, 1B, 2A etc), such that you should ideally occupy a stall where the other stall of the same number is not in use (ie. if only 1B is in use, either 2A or 2B are OK but 1A will be shared with 1B and so charge slower). The layout of these bays does not appear to be standardized between the different sites.

Some form of signalling is provided for the car to control the charger behaviour. Tesla appear be using powerline signalling (RF carrier over the DC power pins), as proposed for the SAE J1772-2012 DC charging standard. This is confirmed by an interview with JB Straubel (Tesla CTO).

At the Folsom, CA site, supply from the grid is 500kVA at 12kV, from which a transformer supplies 3-phase at 480/277V to the Tesla equipment. It is speculated that the chargers are connected in a Y configuration to give 277V at the input of each charger.

Information from the rating plate on the Supercharger hardware at Harris Ranch (photo 2012-10-20 by DrComputer):
Supercharger 120
TPN 1020473-00-A
TSN 1210000007
Input Voltage 200-480VAC L-L
Input Current 280A @200-240VAC / 160A@480VAC
Phases 3PH+GND@200-240VAC / 3PH+N+GND@480VAC
Frequency 50/60Hz
Output Voltage 40-410VDC
Output Current 210A Max Continuous
Oper.Temperature -30C to 50C
Enclosure Type 3R/IP55
Weight 1320Lbs / 600Kg

[top]Charge Rates

Charging rates are controlled by software in the car, and vary substantially with state of charge, temperature and other factors.

The exact details have varied in different software versions: charging rates first reported when the East Coast superchargers appeared (late 2012) seemed higher than those initially reported for the first installations in California a few months earlier, but this appears to have been caused by different software in the cars: more recent reports show no difference between the different supercharger locations.

A graph is available here showing typical charging rates as of early 2013, with the maximum rate achieved around a state-of-charge equal to 80 miles of rated range and gradually falling off thereafter..

By June 2013, the same maximum rates were being reported (eg in this thread) at much higher states of charge, shortening the overall charge time even though the peak rate remained the same.

In June 2013, an announcement was made of substantially improved charging rates - "charging Model S at 120kW" and "replenish 3 hours of driving in just over 20 minutes". This was reported as being both an increase in the maximum rate and a change in the rate/state-of-charge profile. It is not clear whether this was simply another software change, or if there were accompanying changes to the station hardware.

It was later discovered that batteries in early cars, with an "A" suffix on the part number have different charging rates than later cars, and in particular cannot achieve the higher 120kW charging rate (albeit that no cars achieve the 120kW for very long, with the rate reducing as the state of charge increases). There has been considerable discussion of the importance of this change, and an attempt to quantify it is documented here with a discussion thread here.

Separately, a new version of the Supercharger cabinets has been observed with the total power increased from 120kW to 135kW. This serves simply to increase the available power when two cars are charging simultaneously from one cabinet - charge rates for a single car appear to be the same for both old and new cabinets.

[top]Access

So far, the only vehicles with access to the Superchargers are the 85 kWh Model S, 60 kWh Model S with the $2000 Supercharger option, and the Model X prototype.

[top]Installation details

Plans of the proposed installation at Maddison, WI are available in considerable detail at http://www.cityofmadison.com/plannin...9etm_site2.pdf

This confirms the use of 480/277V three-phase with neutral supply to the superchargers, each supercharger feeding two charging stalls. The provision of conduit at this site enforces the link between particular charging stalls and individual supercharger cabinets: there is no easy route to a more flexible sharing of available power between cars parked non-optimally.

Details of the charge cable show it having the familiar J1772 connections for pilot/proximity, a temperature sensor, and a 3.3V supply (presumably to operate the transmitter that opens the charge port door, similar to that on the HPWC/UMC that is known to use a 3.3V supply).

[top]Sources

Contributors: , Created by , 2012-09-29 at 06:27 PM
Last edited by , 2014-08-20 at 01:48 PM
Last comment by arg on 2012-10-16 at 02:38 AM
2 Comments, 11,944 Views

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