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Clean Transport Published on March 8th, 2019 | by Dr. Maximilian Holland
Supercharger V3 — Shocking Power & Smart Strategy By Tesla (Charts!)TwitterLinkedInFacebookMarch 8th, 2019 by Dr. Maximilian Holland

Supercharger V3 stalls look almost identical to this V2 stall, but will eventually come with thinner, liquid cooled charging cables.
On Wednesday night, the eagerly anticipated Tesla Supercharger Version 3 (V3) technology was unveiled, allowing the Model 3 Long Range to receive peak charging power of 250 kW! That’s well beyond the power levels expected by seasoned Tesla tech analysts (myself included). What does this all mean? Let’s dive in and discuss this new Supercharger technology.
In this article I want to outline some initial analysis of V3 and discuss some of the implications. I’m going to look separately in a coming article at what it means in practical terms for charging times on road trips and the like. In short — Tesla is obviously giving us EV technology that smooths away residual friction for fossil-driving folks considering whether or not to make the jump to an electrifying transportation life.
Estimated Charging CurveLet’s dive in first with some modeling of what the charging curve of the Model 3 Long Range on Supercharger V3 might look like (and compare it with the maximum charge power recorded on Supercharger V2):

Allow me first to note that I’ve called this an estimated charging curve, and called the current Supercharger parameters “Beta.” There are a couple of reasons for this: Tesla’s blog article about V3 makes it clear that the company considers the present hardware and software settings to be a public beta, and it is looking to “review and assess” the early results before rolling out more hardware and potentially tweaking the software and parameters next month. The other reason for sticking on labels of “Beta” and “Estimated” are that the announced (and 3rd party documented) Supercharger V3 parameters have come as a big surprise to me and other Tesla hardware geeks. One well known and highly regarded Tesla community geek and detective (whose name we will gracefully not speculate on) said to me “how is that possible?” Personally, I was predicting peak charging on Model 3 of not much more than 160 kW, and “never” more than 175 kW! I’m going to have to stick some small print on my Tesla hardware predictions from now on. 😉
The charge curve I’ve modeled above is based on what we know so far:
Maximum peak power is 250 kW on the Model 3 Long Range.This corresponds to a peak of “up to” 1000 miles added per hour charging.5 minutes of (sweet spot) charging gives up to “75 miles” of “peak efficiency” range (likely EPA city range), which is slightly less than gained from 5 mins @ 250 kW and the “1000” rate (above).Thus, we can deduce that 250 kW is a short peak lasting a little under 5 minutes.Videos (including 3rd party videos) suggest 250 kW peak power starts somewhere before 10% state of charge, and sub-5 minute duration points to likely taper starting not much beyond 20%.Videos show that the Model 3 screen estimates charging from low levels to 80% still takes around “27 minutes” and to 90% takes “35 minutes.”Thus, we know that after the short peak, there is still significant power taper at higher states of charge.The curve is a decent fit to all of these parameters (I’ve run the numbers in geek-level detail on the spreadsheet that generated this curve). Obviously, this curve (as well as Tesla’s above factoids) specify peak performance (“up to”) under ideal conditions. You’ll rarely hit all conditions in the real world for perfectly optimal charging — but if you do, the result could be something like this curve.
However, as I noted above, Tesla may anyway tweak the parameters it has so far specified, based on results of the Beta testing. There are also alternative mild variants of the above curve that could give a similarly close fit to the parameters. I should add that charging from the typical 10% starting point to a high of 80% can take just under 25 minutes — significantly faster than on V2 (around 33–35 minutes). Note that the maximum recorded charge power values on V2, as indicated in the orange dotted curve, come from the data gathering and research of our friends over at A Better Route Planner (ABRP).
As a final note on the curve shape, aside from the unprecedented power levels, the profile characteristics (especially the very early peak) do have precedent in a Tesla. Check out the charge profile of the older Model S 70 kWh battery pack (again from ABRP data gathering):

What Does It All Mean?Designing an early high peak of the charging power is a smart strategy by Tesla for a number of reasons. Most importantly, it is the safest way of charging quickly whilst protecting the battery — the power still tapers steeply back to well established power levels after 50% state of charge, to prevent over-stressing the batteries.
We know the Model 3 Long Range battery pack is good for 330 kW of peak power output, so 250 kW (for a short period of under 5 minutes) is within reason. Tesla by now has extensive data and knowledge about the performance of these batteries over long periods and diverse conditions and use cases. The early peak power is more efficient since, on a given charge session, a good proportion of owners will often need only a given amount of additional range to complete their journey — and not need to recharge all the way to 70% or 80% (or more), when 40 or 50% may be sufficient.

Front-loading charging power and added range in this way is more efficient overall than delivering the peak power at 60–80% state of charge as many other EVs do. This happens mainly because most non-Tesla EVs spend the majority of the charging cycle at power levels that are in fact limited by the maximum current (amps) of the charging hardware, and the pack voltage — which cannot be adjusted post-hoc — is gradually climbing throughout the charge session. Recharging a battery is by definition lifting its voltage back to maximum potential difference (volts). As a consequence, on a charger whose current is maxed out for most of the charging session, the peak power is necessarily somewhere in the second half of that session, when the voltage is closing in on its peak. Newer and more powerful public chargers are improving this by moving to much higher levels of current (amps) delivery, up to 500 amps in many cases. This may allow some EVs to change the shape of the charging curve. Tesla designs both the vehicles and the chargers, so can have a more coordinated approach to this optimisation task than any other EV maker can.
Amp It Up!Whilst we’re on the topic, this question of current (amps) is the main reason for surprise about the Supercharger V3. Let me explain. The Model 3’s battery pack has a nominal voltage of around 355 volts. Nominal battery voltage is usually somewhere near the midpoint of full charged voltage (high) and fully depleted voltage (low). For lithium-ion chemistry cells, this often varies between roughly 4.2 volts when full and roughly 3.0 volts when discharged, with a nominal value around 3.6–3.7 volts (i.e., the full voltage range is roughly 15–20% above or below the nominal value). For the Tesla Model 3’s overall pack with 355 volts nominal, this suggests that when charge is depleted, the pack voltage is likely around 300 volts, and when full, around 410 volts.
If this is correct, then the 250 kW of peak power is delivered to a nearly empty pack whose voltage is likely somewhere in the range of 310–320 volts. Since watts is a function of volts * amps, to achieve 250 kW at ~315 volts, the peak current has to be somewhere close to 800 amps, which is unprecedented for EV charging! Geek forecasters were under the impression (on the basis of solid evidence) that the Model 3 had hardware limits of around 525 amps. Something approaching 800 amps (even for a very short peak) was well beyond any expectation. Bear in mind that the designed-to-be-futureproof CCS 2.0 charging specification (that the Model 3 in Europe is compatible with) currently taps out at 500 amps. 800 is a big number and a big surprise.
The Supercharger V3 hardware is reportedly also capable of delivering up to 500 volts (though likely not simultaneously with 800 amps). This bodes well for future Tesla EVs that may boost pack-nominal voltages up by 20% or so. If you’re interested in the possibility of Tesla raising pack voltages, I discussed this in another recent article looking at Supercharger V3 (much of which now looks hopelessly low-ball, given what has transpired)! The Audi e-tron and Jaguar I-PACE have nominal pack voltages of around 425 volts.

Smart StrategyWhat else can we say about this elevated peak power? In V3, peak power is assured because the system design gives dedicated power to each stall, not kilowatts at risk of being shared (and reduced) by the back-end power cabinets having to do double duty across two stalls. The Model 3 will also have a pack-preconditioning feature that will attempt to get the pack close to the ideal temperature for high-power charging when the vehicle knows you are heading for a Supercharging session. This allows the pack to receive higher power levels than would otherwise be sensible (for pack health and longevity).
Tesla has said it expects the average Supercharger session duration to be reduced by around half. This leads us to another reason why early peak power is a smart strategy by Tesla. The expectation of halving average charging duration is not because the average charging power has doubled over the entire charging session (it is only double for the first 20% to 30% or so, then gradually approaches the V2 charging regime, and is not much different from V2 from 50% state of charge and above). No, the prediction of average charge duration being halved is because, unlike on..