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Anyone have Model S charging information?

I did a search on Tesla Model S charging white papers and all I came up with was press release related information on Tesla's Superchargers.

My Zero has an on board 1kw charger that charges the battery at 1/9C (9kw battery). It accepts 110 or 220V via a standard (high current) IEC printer type power cord. The 2013 models will also accept a CHAdeMO high speed charger. The Zero's battery is around 65V fully charged so the charger is a simple rectifier (AC to DC) regulator combination. The Model S seems to have a lot more going on.

I ordered my S with two on board 10kw chargers. There seems to be a few cord options (wall chargers) and the Supercharger route. Can someone shed some light on what happens between 110V, 220V and Superchargers and the battery with the Model S? My assumption is that all batteries have the same fully charged voltage and that capacity is determined by the number of cell sets in parallel. So, some of my questions would be-

The Model S comes with a Mobile Connector. Is this a simple direct cord from my wall outlet to the plug under the brake light lens?
I ordered the twin chargers which I assume takes the car from having one 10kw charger to two of them on board. Is this correct?
What is the High Power Wall Connector? I ask because $1200 would indicate it is something more than a simple cable from the wall to the car.
Is the connector under the brake lens the only charging connector on the car or does the Supercharger use a different connector?
Does the Supercharger supply high voltage current limited DC directly to the battery bypassing the on board chargers (be they one or two)?
What is the battery voltage of a fully charged battery?
Is the Supercharger supply under the direct supervision and direction of an on board battery management system?

Thanks for helping to fill in these gaps for me

This link answers some of your questions

Ok From Tesla's web site
Standard cable with 240V and 40 amp service (240V * 40 amps => 9.6kw) will source the full single on board 10kw charger.
The High Power Charger is "twice the faucet" to support two on board chargers. The charger documentation indicates it requires 100 amp service (at 220V of course). Does the High Power Charger simply take the 100 amp 220V service from the back side of it and supply this to the car? Does it use the exact same car side connector and connect to the exact same socket beneath the lens? Put differently, is the connector beneath the lens a 100 amp connector?

can you fill in the rest of the answers?

There is only one "socket" on the car, which accepts the same physical connector that's present on the HPWC, mobile connector or superchargers. The superchargers do bypass the onboard chargers and dump DC directly to the battery, though it's regulated by the car to control rate of charge depending on the current charge level.

I don't know the battery voltage

The mobile connector is not quite a simple cord. It has a button on it that causes the charging port to open when pressed.

Thanks for the info. That helps.

Only on connector is used and we know it can handle 100 amps when using two on board chargers. A quick back of the napkin analysis of the Supercharger whould look something like-
Superchargers provide 90kw of DC
The connector is good for at least 100 amps
9000w/100amps => 900V battery fully charged

That is one bad a** battery.

If the current capibility of the car side connector is more then the battery voltage will come down.

Any chance of the technical side of Tesla joining in on this conversation?

For sure the HPWC does not supply 100 Amps to the car. It is rated at 80 Amps. The electrician that installed the sub-panel and wire in our garage told me that the "derating" of 20% is to recognize continuous load for more than one hour. Most of us (including Tesla employees) can not tell much more about the HPWC because it is not yet available. I could not even find out where the knockouts are located. It is my understanding that the logic for control of charging is on board the car. And, yes the car side connector is most likely rated at 100 Amp because it is the same for single and dual chargers.

Superchargers operate significantly above 100 amps, probably close to 200. They don't use the mobile connector, but they do have a male plug that fits into the same port on the car. Obviously they use heavier wiring than the mobile connector or HPWC.

Regarding battery voltage, I asked in another thread, and got this response:

jkirkebo | NOVEMBER 5, 2012
Battery voltage is around 365V nominal. Over at one of the supercharging-treads, someone reported a starting voltage of 358V when charging from ~22% SOC and an end voltage of 396V when full (after 65 minutes).

This is the thread:

I think you're thinking of voltage incorrectly. Voltage is basically the electrical "pressure" of a circuit. If you're comparing to a gas engine, it would sort of be the PSI of the gas coming out of the tank. And as you might surmise from the example, that value is not really important in terms of how powerful the battery is or how long it lasts. It's certainly related to the wattage and amperage of the battery, but it's more of a derivative value than one that factors into play.

Amperage is important because it represents the flow rate of electrons into or out of the battery. If you're dumping in the 100A HPWC (actually 80A because of breaker overhead), you're obviously putting in much more than the 12A of a standard wall outlet or even the 40A from a NEMA 14-50. In an ICE, this is how much gas you're pumping into the engine, as controlled by your foot on the accelerator or by how much you squeeze the handle at the pump. You're opening that valve more, so if there's sufficient pressure behind it, a lot of gas either goes in from the pump or out into the engine.

Similarly, on the S, if you press down on the accelerator, you get a boost in amperage, as you've opened up more of the battery to push through to the engine and move the car forward. Or on the charging side of the fence, you'll find that you usually get 120 or 240V service and it's just a matter of which size "hose" you can plug into it. It's all over the same connector (though it's usually adapted to different plugs), so the source of electricity determines your amperage/voltage, and therefore your charge rate.

Hope that helps and wasn't too rambling!

I can vouch that the current at a Super Charger is up to 225Amps - I witnessed this while charging my car at the Super Charger station. The display also showed 396V.

So, the socket (or receptacle) on the car can take 396V@225A which is almost 90KW of power! This gives an 85KWHr battery a full charge in a little over an hour - the charge rate drops as the battery gets full (to protect the battery life).

225A is an amzaing amount of current. I once designed board on a system where we had 300A running at 5V. There was oxidation on the connector and the whole connector assembly melted due to the heat caused by the small resistance in the connector system. That technology was 30 years ago - I'm sure connector technology has come a long way since. The connector contacts appear to look silver color (not copper as I would have expected). I wonder if they are aluminmum - which is what the electric company uses for wiring from the utility pole to our home. Maybe the superchargers also use aluminum wire? I noticed the guage (thickness) of the aluminum wire coming to the service stalk at my home is much smaller than the copper wires they connect to that serve my 200 Amp electric panel.

@timdorr, you're right, except that the proper analogy isn't the "push" of the voltage. It is the "pull" of the motor. I.e., the battery operating at 365 volts isn't pushing electrons into the motor; rather the motor is drawing current from the battery. That's why it is perfectly fine to plug a 10 watt light bulb into a 110 volt circuit. The bulb draws only what it needs.

Definitely too rambling.


The Lithium charge profile is constant current until the battery reaches a set voltage followed by constant voltage until the battery reaches a termination current. The largest load demand on the supply occurs at the cross over from constant current to constant voltage (396 VDc in this case).

90,000 watts / 396 VDc => 227 amps which is HUGE

It makes sense that there would be a separate set of contacts for Supercharging.

So, to summarize-

The cable that comes with the car has a dongle element that opens the brake lens hatch to expose the charging connector in the left rear of the car.
The cable that comes with the car requires 220V 40 amp service to fully support one 10kw on board charger. This would be similar to a dryer circuit.
The High Power Wall Charger requires 220V and 80 amp service to fully support the optional two 10kw on board chargers.
The standard charging contacts on the car side connector must be capable of handling 80 amps continuous current.
Supercharging uses the same connector area under the tail light lens but different contacts. Instead of AC, the Supercharger station provides up to 227 amps of current regulated power at up to the pack voltage limit of 396 VDc. The on board chargers are not needed/used when Supercharging.

That all makes sense. Now it is time to go back to the latest 4/3rds A fat Sanyo cell data sheet and see how many of these batteries are being used in series to generate the pack's voltage and how many sets are used in parallel to provide for the three battery pack options.

It is interesting that a Supercharger unit actually consists of a dozen of the same chargers that are installed in cars, stacked in series. Elon said that is what makes it so economical for them to put up so many so fast.

It would make sense given they seem very comfortable with the basic 10kw charger as a bilding block.

Lots of assumptions here.............

Panasonic Number Nom V Capacity Diameter(4/3rds Fat A type)
CGR26650B 3.6 3300 1.04"
CGR18650KA 3.6 1750 0.73"
CGR18650CH 3.6 2250 0.73"

Using the highest capacity cell from above (the standard 4/3 rds Fat A cell with the larger diameter 1.04") will yield number of cells in series to reach the Model S' nominal voltage. 365V/3.6v => 101 cells. Let's use 100 for round numbers.

Each series set of 100 cells provides 3.3 amp-hr of capacity which translates to 1188 watt-hr (3.3 amp-hr * 3.6 v nominal * 100 cells => 1188 watt-hr). This equates to the following number of series sets and batteries per Model S option-

Pack Capacity Number of Series Sets Total Number of Cells
40kw 33 3300
60kw 50 5000
85kw 71 7100

That 7100 number seems to be close to what I've been told the 85kw battery has.

Here's a pseudo-table using <pre> and <h2> tags:

Pack Capacity Number of Series Sets Total Number of Cells 40kw 33 3300 60kw 50 5000 85kw 71 7100

AFAIK Model S uses NCR18650A (not CGR-series), which are not quite standard, but close (something special made for them by Panasonic for Tesla, maybe coating is different or something like that).

I used a lot of assumptions. I was more interested in getting a handle on the overall concepts employed and hopeful others (like Timo) would be kind enough to populate the thread with details.

Thanks Timo!

The individual car chargers in the superchargers would be stacked in parallel (not in series), since each car charger already produces the needed voltage. In parallel the currents are added, voltage kept the same. (in series, voltages are added, current stays the same).

I thought the number of cells was public knowledge. I don't know what the number is, but I seem to recall it was north of 8,000. Was that just a guess?

I'm sure someone at Tesla has said at some proint what the battery configurations are. I was hoping there would be a white paper somewhere were they provided nerd type details. I did not find one so I started the thread to fill in as much detail as I could about everything from number of batteries to how the capacities are generated and why there are different charging cables and the like.

The more I understand the details the easier it is for me to make informed decisions. It also helps me understand more than just the options proposed/provided by Tesla at this point in time (like fast charging at home).

I need to go back and adjust my calculations based on the cell information provided by Timo.

Bill, you may have already seen this, there is a Tesla write-up about the Roadster battery. I would think they continued along the same architecture for the Model S, of course with significant improvements.


In timdorr's analogy I actually find the term "push" to be more useful in understanding what is going on practically.

Your argument is based on the fact that many people use the term "draw", but if anything it is the use of this term which is misleading and/or "incorrect".

Remember that work requires an energy source. The terms "push" and "pull" imply that work is being done (we know this is the case), but which side does the energy come from?

Timdorr used the common analogy of voltage = pressure:
1. Let us consider then a hydro-turbine.
2. The energy source is the water in the dam.
3. The water pressure pushes the turbine around.
4. The turbine does not pull the water down from the dam.

In the case of a Tesla's electric motor:
5. The battery is the energy source.
6. The voltage pushes electrons through the motor.
7. The motor impedance and control circuit limit the current.

In the case of regenerative braking:
8. Energy source is the moving car's mass and/or altitude.
9. This kinetic energy turns the motor (acting as a generator).

@Carl Barlev,

In an electrical circuit, it is the "work" end that determines how much current flows. When you replace a 50 Watt bulb with a 5 Watt bulb, the voltage of the circuit stays the same. The smaller bulb simply draws less current from that circuit. When you want a brighter light, you don't increase the voltage; rather you put in a bulb that will draw more current.

Your example of a hydroelectric is telling. While it is true that water pressure pushes the turbine around, the amount of water flowing through the turbine (as opposed to down the spillway) is controlled by the load. When you apply a large load, for example by supercharging your Tesla, it literally causes the turbine to spin faster. You don't spin the turbine faster in order to push more electricity into the charger.

Most blackouts occur not because generation fails, but because the load exceeds what the generators can produce.

I'm not an electrical engineer, but I've spent a lot of time around electrical engineers, and this is always how it has been explained to me.

"So, the socket (or receptacle) on the car can take 396V@225A which is almost 90KW of power! This gives an 85KWHr battery a full charge in a little over an hour - the charge rate drops as the battery gets full (to protect the battery life)."


Thanks for the information.

I'm trying to get a feel if the Supercharger tappers the charge down to an High Power Wall Connector (HPWC)rate or whether its higher. For instance, suppose the Supercharger charges at an average rate of 300 miles of range for the first 150 miles, but then charges at an average of 62 miles of range for the last 115 miles (in range mode), one would expect a total charge time of around 2.4 hours.

You stated that it took a little over an hour to a full charge so I'm wondering did you do a full charge in Standard or Range mode? What was your intial state of charge when you started Supercharging?

Did you get a feel for when the Supercharger starts to drop the rate of charge? Was is at 50%,75%, etc?

If your car was at a low state of charge then the last 115 miles in Range mode would have to be at a rate higher than an HPWC to get a full charge in a little over an hour.


It declines on a curve, not like a switch. From 300 mi/hr (average, assuming low SOC to start), to 295, to 290, to 285, to etc. But smoothly.

Thanks, I know that. I'm looking for some examples from Model S owners of actual charging rates as the batteries nears a full charge.


Lithium Ion batteries charge at a constant current up to a certain voltage (determined by the chemistry). Once at this threshold voltage, the charger will reduce current to maintain that voltage. Once the current falls below a threshold, the cell is considered charged.

Practically speaking, this means a cell in a low state of charge (SoC) will charge at a high rate. Once the constant voltage is reached and the charger starts reducing the current to keep from exceeding that voltage, the charge rate slowly diminishes to zero.

You can find a typical charge curve here -

This is a 1.8 Amp-Hr cell
The charge profile here is ROUGHLY
The constant current portion is 120 minutes * .9 amps or 2 Amp-Hr
The constant voltage portion is approximately half of a right triangle with a height of .9 amps and a length of 2/3rds of an hour or .3 Amp-Hr
The total charge current in is 2.3 Amp-Hr in this example
The constant current or high speed portion is 87% of the charge cycle
The slower constant voltage portion is the remainder; 13%. The first part of that 13% being almost as fast as the constant current with the last part being way slower.
Note that, for this sample charge curve, it took 2.3 Amp-Hr of charge current in to achieve 1.8 Amp-Hr of charge state. This is "current" charge efficiency. Charge efficiency can also be looked at in terms of Watt-Hr in per Watt-Hr out which is even less efficient.

The Supercharger concept for cross country travel probably relies on charging in the constant current realm for maximum bang for the minute.

Blew it
Constant current portion is 1.8 Amp-Hr
Total charge in is 2.1 Amp-Hr
Constant current is 86% with 14% being constant voltage
Current charge eff is 1.8/2.1 or 86%.

' hope these numbers are closer to right.

Thanks Bill I found out what I was looking for here: