Welcome back everyone! I’m Jordan Giesige and this is The Limiting Factor.
In the last video I covered the immersion cooling technology unveiled at the Tesla Semi event and
what that means for the V4 supercharger. However, I didn’t spend much time on the megacharger, which
I speculated was actually a different product than the V4 supercharger and capable of over two
megawatts of power output rather than one. So today, I’ll explain my reasoning for a
2 megawatt charger, evidence against that, and the grid related implications of Megachargers.
Before we begin, a special thanks to my Patreon supporters and YouTube members. This is the
support that gives me the freedom to avoid chasing the algorithm and sponsors. As always,
the links for support are in the description. Let’s pick up where we left off in the
last video. I expect Tesla to have four versions of vehicle charging
infrastructure in place by later this year. First, the old Version 2 chargers that
have around 150 kilowatts of power output. There’s still quite a few of these around,
but the technology is now about a decade old. Second, the current generation Version 3
superchargers that have 250 kilowatts of power output. I’m guessing that,
as per Elon’s hint in this tweet, that those will all be upgraded to 300 kilowatts of power output.
Third, Version 4 of the supercharger, which is launching this year. Tesla hasn’t provided a
number yet, but I’m hoping for at least 500 kilowatts so that the long range version of
the Cybertruck can charge at the same rate as the rest of Tesla’s vehicle fleet. If you’d
like to know more, check out the last video. Fourth, and finally, the megacharger for the
Semi. Again, Tesla hasn’t provided a specific power output, but I’ve listed 2 Megawatts because
my view is that’s what will be required for the Semi. Let’s take a look at the evidence for and
against my estimate. Tesla set an expectation of over 1 megawatt of power output at the Tesla Semi
event. This aligns with reports from early last year that stated that it would be 1.5 megawatts.
However, in the most recent report from late last year, Pepsi told Reuters that they would
be installing four 750 kilowatt stalls. They also said that the semi charges 80% in 35-45 minutes,
which means there’s a discrepancy here: 750 kilowatts of steady state power is only
enough to provide around 450 kilowatt hours in 35-45 minutes. The Semi battery is at least 900
kilowatt hours, which means a about a 50% charge in 35-45 minutes with a 750 kilowatt charger.
A 50% charge 35-45 minutes doesn’t align with what Tesla’s advertised for the Semi, which is a 70% in
30 minutes. If they’re advertising that, it would surprise me if they don’t have a charger that can
provide enough power to support that claim. What would a 70% charge in 30 minutes take?
As I said a moment ago, the semi battery looks to be rated for 900 kilowatt hours or more. The 2170
battery cells that are likely being used in the Semi are also used by the long range Tesla model
3, which maxes out at a 3C charge rate when fast charging. A 3C rate means the ability to charge at
power input that’s 3 times the kWh rating. In the case of a 900 kWh battery, that’s 2.7 megawatts.
However, the 3C charge rate is for a 0-80% charge in 30 minutes rather than 0-70%. To account for
the difference between the 70% and 80% charge rate, I’ve multiplied 2.7 megawatts by 7/8ths
to arrive at 2.3 megawatts. That’s a very rough number but I think it puts the charger requirement
for the Semi at, at least, 2 megawatts. Some people might point out that a 70% charge on
a 900 kilowatt hour battery pack is 630 kilowatt hours. If that power needs to be delivered in 30
minutes, wouldn’t that mean the megacharger only needs to supply 1260 kilowatts of power? No,
because provided that the cells are well cooled, the charge slope is dictated by how quickly the
battery can store energy at the chemical level. If we again use a Tesla model 3 battery as an
example and scale the charging power to the Semi battery pack, from a 0-35% state of charge,
the average power output would be about 1600 kilowatts. And then, from 35-70% state of charge,
it would be about 1000 kilowatts. The average of those two numbers is 1300 kilowatts from 0-70%,
which is near the 1260 kilowatts of average power that would be needed if there was no charge slope.
What are the ways that I could be wrong on how much power the Semi can accept or how
much power the megacharger can supply? First, it may be a situation where Tesla starts with
a conservative charge rate and increases it over time. The Model 3 standard range plus
started with a 100 kW peak rate, and it was soon unlocked to 170 kW through a software update.
Second, if Tesla’s using a battery cell with a different chemistry in the Tesla semi,
it may have a different charge slope than Tesla’s other vehicles. But that seems unlikely because
there’s usually a compromise required where higher charging speed means shorter cycle
life or lower energy density, both of which would be priorities for the Semi.
The third way I could be wrong is if I have a fundamental misunderstanding of how the
Semi battery would charge. If you think I do, let me know in the comments below.
Fourth, Tesla says up to a 70% charge in 30 minutes. There are two versions of the
Semi. Maybe only the 300 mile range version with the smaller pack will get enough power
from the megacharger to hit the maximum charge rate. But, that would go against the reports
on the long range Frito-Lay units, which are getting an 80% charge in 35 to 45 minutes.
Fifth and finally, it could be that although the base architecture and immersion cooling of
the Megacharger is good for 2+ megawatts, they’re still working out kinks. That is,
the current Megachargers are a quick and dirty 1st generation that’ll soon be replaced. This
happened with the V1 supercharger, which was replaced about six months after it was unveiled.
In light of all the conflicting information on the Semi and Megacharger, I’d say the likeliest
power output will be in the range of 1.5 to 2 megawatts, with the upper end being around
2.3 megawatts. That’s actually modest when compared to where the rest of the industry
is headed. If Tesla’s charger only hits 1.5 megawatts, it would have less than half of the
power output of the Charin standard, which is expected to deliver 3.75 megawatts next year.
As a side note, as “its kyle conner” points out on Twitter, Tesla’s a member of Charin
and some people were expecting that they’d use the massive 3.75 megawatt Charin plug. However,
according to the Executive Director at Charin, Tesla’s not using the Charin plug.
If that’s correct, then it supports my view that the Megacharger plug used at Frito-Lay is
the plug that Tesla will use long term because Megacharger and Semi Deliveries have already
started. I could still be wrong, but Kyle’s thread provides some support for that view.
What about Pepsi’s claim of 750 kilowatt charging stalls? It could be that they’re referring to
average power per stall. If there are four stalls at 750 kilowatts, that means 3 megawatts of total
power on tap and the Megacharger might be able to shift power to whichever stall is in use.
For example, if one Semi is plugged in, depending on whether it can draw from the adjacent stall or
all four stalls, it might be able to draw between 1500 to 3000 kilowatts. So Pepsi’s claim doesn’t
necessarily conflict with the other information we have, we may just be missing detail.
Let’s move on to the grid related implications of Megachargers. To do that,
we first need to get an appreciation of how much power is used by a megacharger.
The building on screen is 400,000 square feet, or roughly 40,000 square meters. On average,
a building like this would use about 1 megawatt of power at steady state. So, if the megacharger
uses 2 megawatts of power at peak output, 1 megacharger would be drawing as much power from
the grid as two large commercial office buildings. And, of course, each megacharger station will be
able to charge multiple semis at once. In fact, for a large distribution hub for a
package delivery company, you’re looking at over 500 trucks rotating on and off the Megachargers.
The numbers get insane pretty quickly. At city or regional level, you can bet that
when there’s hundreds of thousands of Battery Powered Semis on the road, you could expect 500
semis charging at the same time at peak power. 500 semis charging at 2 megawatts is 1000 Megawatts,
or 1 gigawatt of power. The nuclear power plant just north of where I live only puts
out 850 megawatts of power, so we’re talking a serious impact on the grid just from semis
and not including passenger vehicles. Let’s get back to a more manageable
scale. The Frito Lay megacharger station has 4 stalls. Let’s assume each of those stalls
fully charges six semis a day. I’ve picked six semis relatively randomly,
so feel free to insert your own assumptions. 4 stalls at six semis each is 24 charges a
day. If each Semi pack is 900 kWhs, that’s 21.6 megawatt hours. If we bring back our 400,000
square foot office building with an average hourly usage of 1 megawatt, that’s 24 megawatts. So even
at just 6 semis per day per charging stall, the Frito Lay charger would not just be using
as much peak power as a large office building, it would also be almost as much total energy over the
course of a day, and that’s being conservative. That is, Megachargers will need to be built in
locations with a fairly robust grid or Tesla’s going to have to reinforce the grid where they
build the megacharger stations. This will be especially true when they start building 8, 16,
or 32 megacharger stations for industrial parks, Truck stops, and large distribution centres.
Power at that scale means those stations may need their own distribution substations to
pull down high voltage power from transmission or subtransmission lines. My understanding is
that the lead time for the equipment to build substations is currently around 1-2 years. But
what if instead of using a substation, Tesla used a smaller grid connection and
buffered it with megapacks and solar panels? For those who don’t follow Tesla, a megapack
is a large battery system that can store over 3 megawatt hours of energy per unit. Megapacks
are placed near solar or wind farms to capture intermittent energy or can used to reinforce the
grid in place of peaker plants. They store power when not much power is being drawn by customers,
and then release the power when its needed. That is, megapacks could be used to buffer the
power demands of V4 superchargers and Megapacks in place of a larger a grid connection or substation,
and that appears to be what Tesla’s doing. First, as per the Supercharger Goat on Twitter,
indications are that Tesla’s first V4 supercharging station will use a megapack.
The megapack will be coupled with a solar farm to provide an additional power buffer, reduce CO2
emissions, and reduce Tesla’s power bill. Second, the Frito-Lay Megacharger station we discussed
earlier is also reportedly also using a megapack. Let’s take a step back and look at the strategic
implications of Megapacks for Tesla’s charging network. Tesla has the largest
DC fast charging network in the US, with 58% of the chargers. Not only that, Tesla chargers
almost always work. This is as opposed to some other charging networks where about
half of the chargers often aren’t operational. The supercharger network is clearly a competitive
moat for Tesla, but that moat may just get wider and deeper. When more vehicles with
larger battery packs like electric semis, large pick-up trucks, and vans hit the road, megawatt
DC fast chargers will become essential. But, they clearly require a lot more infrastructure,
which will make it more technically difficult and costly to build them out.
As far as I can tell, Tesla is the only company in the US that’s vertically integrated enough to
build megawatt charging stations at scale in the hundreds or thousands within the next few years.
This is because they build their own DC fast chargers in house, they’re the only company mass
producing grid scale battery packs in the tens of gigawatts, and they have access to large supply of
battery cells from a range of manufacturers. Beyond using megapacks at charging sites for
vehicle charging, there’s also an arbitrage opportunity here. What do
I mean by an arbitrage opportunity? Tesla has sophisticated grid management software
for the megapacks, which allows them to buy and sell power from and to the grid.
The megapack can draw cheap power from the grid during off-peak hours and release that energy
back to the grid during peak hours at a higher price. That not only means more profits for Tesla,
but also a more stable grid because the megapacks will be acting to buffer the swings that occur
between peak and off peak power demand. That’ll become increasingly useful as the proportion of
intermittent, renewable energy generation on the grid increases with solar and wind deployments.
In summary, my view is that the megacharger will support a power output of over 2 megawatts. That’s
because based on the charge curves of Tesla’s other vehicles, 2 megawatts would be required
to hit the advertised charging speed of the Semi, which is a 70% charge in 30 minutes
However, 2 megawatts conflicts with reports of 1.5 megawatts or even 750 kilowatts. If those
reports are correct, I suspect it wouldn’t be to do with the base architecture of the megacharger.
This is because the base architecture will need to be capable of multi-megawatt
charging to future proof the megacharger against competing standards like Charin,
which has plans for a 3.75 megawatt charger. Rather, if the Megacharger does charge the
Semi at 1.5 megawatts or less, it could be that Tesla is taking and abundance of caution with the
new Semi battery pack like they’ve done with past battery packs or that they’re expecting
to rapidly iterate on the megacharger like they did with the 1st generation of the Supercharger.
If I’m incorrect on both the maximum charge rate and the reasons why there might be a lower charge
rate, I’ll be eager to make a video on why. That is, as soon as I figure out how Tesla defeated
the charge curve and where my understanding of battery charging technology is lacking.
Either way, I expect most megacharger and V4 supercharging stations will require a megapack
because even four megacharger stalls would use as much power as a large commercial building.
The only alternative I could see would be to build substations at charging stations. But that
would mean higher operational costs because there would be no way to buffer cheap power
at off peak rates and it would also handicap Tesla’s ability to grow because the wait times
for substation equipment are 1-2 years. For the icing on the cake, the Megapacks
installed at Tesla’s charging stations may offer an arbitrage opportunity. For each
charging station that Tesla builds, they’ll also be building a small power plant that will generate
profits by buying power at off peak rates and selling it back to the grid at peak rates.
The only potential limiting factor for Tesla here seems to be access to battery supply. The
manufacturing ramps for the Semi, Cybertruck, and megapack will require an extreme supply of battery
cells on top of the extreme supply required to ramp Tesla’s passenger vehicles and Powerwall.
Will Tesla have enough battery cells for an aggressive ramp of all these projects at once?
According to Tesla, they do for the time being, but it’s something I’ll keep a close eye on.
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