Have you ever wondered what’s inside one
of these electric car chargers? Well then, this is the video for you! The short answer is, not a lot really. The longer answer has to do with how electric
vehicles charge themselves because this isn’t actually a charger. The industry name for this device is EVSE,
which stands for electric vehicle supply equipment. Kinda weird that we’re calling it “an
equipment” but let’s not get any more pedantic than this video is already guaranteed to be. Fundamentally, this device is merely a controlled
access point to the power grid. I’ve been wanting to make this video for
a long time but finally got motivated to do it thanks to a series of interactions on Twitter. You know who you are. First, qualifications; this video is discussing
Level 2 AC charging in North America. Those of you with your fancy three phases
need not comment on your Type 2 connectors because yes, I know they exist in Europe, Australia,
and elsewhere but they do not exist over here so mentioning them is irrelevant. DC Fast Charging, the most famous system of
which being the Tesla Superchargers, is not where we’re headed either. Not today, anyway. Instead, this video is about quote unquote
“slow” at-home or at-the-office charging and the devices which make that work. Unless you plan on exceeding your vehicle’s range in a day (in other words are doing long distance travel) this is how the vast majority
of your charging will (and in my opinion, should) occur. I very much hope we focus on getting more
level 2 chargers in more places to help accommodate those who need a car but don’t live in a
single family home rather than make that huge percentage of the population reliant on DC
fast charging, thus replicating the fueling infrastructure we have today but with high-speed chargers instead of gas pumps. Plugging in at home or at work is not only
much more convenient, but requires less radical infrastructure and from my perspective seems a lot easier to manage on a connected smart grid. But the main reason why I hope we go with
the more Level 2 less DC charging route is because these things are stupidly simple devices. I said earlier that these aren’t chargers;
in fact, these are basically just fancy light switches. Let’s explain what I mean. Most things we call chargers are really DC
power supplies. Yes even those aren’t often really chargers. They contain electronic circuitry designed to turn AC mains voltage into a defined and stable DC voltage; in the case of standard
USB that would be 5 volts. The charging is done by the device you give
the 5 volts to because it knows how to treat its battery best. Electric cars are pretty much the same. In the case of Level 1 and 2 charging, they
handle the charging themselves. But they go one step further than your phone
or laptop. Because electric vehicles come in all sorts
of shapes, sizes, battery chemistries, and battery pack voltages, it’s not really feasible
to put the power supply outside of the car. So it isn’t. This device has no voltage conversion circuitry
in it of any kind, except for the wee bit it needs for its own electronics. A reminder to the keyboard warriors out there; we’re not talking about DC fast charging in this video. This device has one job and one job only. To safely deliver AC power to a car. The car itself contains the battery charger. Want to see it? Well, in the Chevy Bolt EV it’s here. These four boxes represent all of the electrical
bits of a Bolt. The Bolt’s Bits. Up on top here to the left is a junction box
which splits out traction battery voltage to the inverter module and high-power accessories
like the air conditioning compressor and cabin heater. Below it is the inverter module which actually
drives the traction motor (and thus wheels) and recovers charge under regenerative braking. On the right up top you have a DC-DC converter
which takes high traction battery voltage and steps it down to 13.8 volts or so to power
accessories and charge the 12V battery (in other words this is the equivalent of an alternator
in a conventional car). And below it is the onboard charger. Side-note, a lot of you may be asking why
an electric car needs a standard 12V lead-acid battery. Technically, it doesn’t *need* it but the
design of the car becomes much safer and also easier if you can run conventional things
like lighting, infotainment, power windows, the computers, etc off of low voltage. It’s easier because it means the things
that are the same from a gas car to an EV don’t need to change - imagine a 400 volt
turn signal bulb. And it’s safer because, well for one you don’t
have high voltage wiring running all over the place, but more importantly when the car
is off and not charging, contactors inside the battery open removing traction battery voltage from everything. What are contactors? Well, you’ll find out shortly. You can actually hear those contactors close
when you turn on the car. [two dinstinct thunks] [Classic General Motors Seatbelt Bong] Or plug it in. [A single clunk, followed by a beep] And obviously when the high voltage system
is shut down, you need something else to close those contactors and turn it back on, and that’s why the bulk of the car’s control systems run at the conventional 12 volts and why there’s
a standard battery, too. Anyway, again, this is the onboard charger. It’s kind of hard to see in situ, if you’d
like a closer look at these components I can’t recommend this video from the Weber Automotive YouTube channel highly enough, it’s fantastic. Also everything is a lot cleaner. But this module here is the actual charger. It takes AC power coming from the car’s
charge port, rectifies it to DC, boosts that up to the battery pack’s required charge
voltage, and sends that into the battery pack. Inside the pack itself you’ve also got various modules which monitor each cell and help balance everything out. Now, here’s where things get a little complicated
and where the critical role of the EVSE comes in. The car’s onboard charger may be capable
of pulling more power from the grid than a given circuit can safely provide. It’s the EVSE’s job to tell the car how
much current it can pull and then to supply it with voltage when requested. Let’s now take a closer look at the device
itself. This is a Siemens VersiCharge unit, a fairly
basic EVSE. It has a NEMA 6-50 plug on one end, and the
industry-standard SAE J1772 connector on the other. Since 2010, every single battery electric
vehicle and plug-in hybrid for sale in the US that doesn’t begin with T and end in
esla has this very connector on it. From the Chevy Volt, the Ford Focus Electric,
the Nissan Leaf, the Volkswagen E-Golf, the Toyota Prius Prime, the Kia Soul EV, the Hyundai
Kona Electric, and yes, even the Wheego LiFe,
they all have this charge port. This connector is part of the universal nationwide
(except for Tesla) Levels 1 and 2 charging standard capable of delivering up to just
shy of 20 kW, though typically most units deliver between 6 and 7.2. This unit, like many out there, is rated for
30A, so depending on the voltage it receives it can deliver between 6.2 and 7.2 kW. We find a user interface on the front of this
device, though not all EVSEs are going to have one. The most useful thing this does is allow you
to delay charging for up to 8 hours in two hour increments, a fairly easy way to take
advantage of time-of-use rates if your utility offers them. Though it should be noted most cars can do
this themselves, in fact on the Bolt EV you can even program that based on GPS location so
it charges immediately when on a public charger, but only between certain times at home. A lot of the symbology on here is, I believe,
shared between multiple models because I don’t think this unit has any sort of WiFi connectivity
(though frankly, I don’t really care either way). Oh, and of course it has fancy lights on it
because what good is driving an electric vehicle if you don’t get to be smug about? Let’s now open it up. You might be surprised to learn that most
of what’s in here is simply empty space. The unit is way larger than it actually needs
to be, partly so it can have those fancy lights to help your smugness, and partly because it
helps manage the cord when not in use. The power leads from the plug (which interestingly
are not colored properly, the white wire should be red since there is no neutral but whatever) go to a terminal block, allowing you to replace the plug or hardwire the unit if so desired. One reason to do that is that this particular
model is weatherproofed and so can be outside if installed and wired properly. From there a few small feeders go to the circuit board, and two large conductors go to one side of a contactor. Out the other side of the contactor you’ll see that it goes to the main conductors of the charge cable. This contactor is the single control device
of this unit. A contactor is simply an electromagnetic switch. When energized it closes, connecting
the charge cord directly to incoming power. When it’s open, it doesn’t. That’s it. That’s all these devices do. They're a fancy light switch. [loud CLACK of contactor] But it is a critical safety device and what
keeps your car from overloading a circuit. Let’s talk about that part first. Keep in mind that the car is the load. The charger is inside the car. This device is simply a gateway to the grid. It is labeled as though it’s a 30A device which makes things easier for regulators and electricians, but in reality the device itself
consumes maybe 5 watts. The car is where the load actually comes from. So first and foremost, it needs to tell the
car how much power it can safely pull. The device can only supply 30A because it’s
on a 40A circuit. Technically it's allowed provide up to 32 continuously, and truthfully I don’t know why they capped it at 30, but anyway the device needs to tell
the car “Hey! Don’t pull more than 30A. You’ll make trouble if you do.” And it does that through very rudimentary
signalling protocols. So, here’s a close-up of the pins on the
car’s side. And now on the plug side. This one helpfully labels which pin is which. The three largest pins are Line 1, Line 2/Neutral, and a safety ground or protective earth. If you’re confused on why pin two is only
sometimes neutral, you might want to check out this video I recently made on the US electrical
system. In short, we use split phase power, and on
a 240 or 208V circuit both pins will be hot, but on a 120V circuit only one of them is. The other smaller pins are the control pilot
and the proximity pilot. Let’s start with proximity. The main purpose of these pins is to tell the car and the
EVSE that they’re connected to each other. On the EVSE side, the proximity pilot and
ground pin are connected via a resistor which allows the car to know it’s plugged into
an EVSE even in the event the EVSE is dead. This completely passive method ensures that
when the car is plugged in, even if the EVSE is faulty or there’s no power to it, it knows it’s connected to an EVSE and won’t let you shift from park. A well-thought-out design preventing the careless
from driving away with the charge point. The control pilot is a little more complicated,
but still not all that much. If it’s awake and ready to charge, the EVSE puts a 1 kHz square wave signal out on the control pilot pin. Without a car plugged in, that circuit is
open so nothing happens at all, but when a car is plugged in, just as there’s a resistor
on the EVSE side for the car, there’s a resistor on the car for the EVSE side. In fact, the car can manipulate the resistance
in order to signal different things to the EVSE. Per the spec, when the car is connected it
should have a 2740 ohm resistance across the protective earth and the control pilot pin. This signals presence to the EVSE. To request power the car lowers that resistance
value down to 882 ohms. That will cause the EVSE to close the contactor,
and then the vehicle can charge. There is also a very special and rare case
where the car will lower the pilot circuit resistance further to 246 ohms to signal that
it requires ventilation when charging. This is used to prevent such a hypothetical vehicle
from being charged indoors. I’m not aware of any consumer-facing applications
where this is in use, but if you were ever wondering why your charger says “ventilation not required” on there - that’s why. It’s to prevent such a car (perhaps one
with lead acid batteries which could produce a lot of hydrogen when charging? Really not sure what would require ventilation) But anyway, to prevent such a car from being charged with this supply. Most importantly, though, that 1kHz square
wave being sent on the control pin is pulse-width modulated to signal the maximum charge current the car is permitted to take. That is arguably the single most important
thing the EVSE does. See, a Chevy Bolt has a 7.2 kW onboard charger. That happens to match the rating of this EVSE
so we’re all hunky dory. But what if I wanted to charge it on a smaller
circuit? Say I had installed a 3.6 kW charger on a
20A circuit. The car needs to know it’s only allowed
to pull 3.6 kW or else it would overload the circuit and trip the breaker. Which is of course inconvenient, but also
you’re then relying on the breaker to actually trip, and if it’s faulty you could very
well have a fire on your hands. Better to not tempt fate. The EVSE is also monitoring the circuit for
any ground-faults and will open the contactor should one occur. They're usually designed to self-reset at least a few times so that you aren’t left without a charge in the morning. And they’ll also self-test things like the
integrity of the protective earth and provide other various protections. But at a core level, all this does is announce
its presence and capacity, and wait for a signal to initiate charging. Then it goes *CLACK* and the car does the rest. So if these are merely fancy light switches,
why are they so gosh darn expensive? It’s not exactly hyperbole to say the functions
of this EVSE could be replicated with an arduino, a contactor from an air conditioning unit, a power supply, and a willing middle schooler. The answer? [incredibly annoying rising "ehhhh" sound] OK well in fairness, there are plenty of options
these days which can provide all that this car can take for around $300. The greatest cost of installing a charging
station will always be simply running a new circuit to wherever you need it to be. Which is why it would be *great* if we could
require at least one 40A 240V circuit for garages in new building codes. But anyway, the charger itself need not be
expensive because it’s a pretty dumb device. I believe I've said this a few times now, but
it is basically a fancy light switch. The greatest cost in these units is almost
certainly the charge cable itself. It’s a fairly specialized and quite beefy
multi-conductor cable, built to withstand a fair bit of abuse. This entire unit weighs something like 20 pounds
or roughly 9 kilograms, but the vast majority of that is just this cable. The actual unit is a plastic box. The connector itself is designed for 10,000
insertion / removal events, which means it should last a couple of decades in a private
setting, and a good few years at least in a public one. The connector’s handle is also a little
more specialized than you might realize. Can you hear the little microswitch in here
when I depress the latch? [clicky clicky noise] This actually adds another resistor across
the proximity pin and the protective ground, which signals to the car that it’s about
to be unplugged. This is actually among the most elegant parts
of this design spec. More or less the instant the car sees that
resistance change, it stops pulling power from the grid. That means that when you interrupt a charge
by unplugging the connector, current flow has stopped before the pins are actually separated
(and indeed before the contactor opens) which prevents arcing and prolongs the life of both
connectors and the contactor inside the EVSE. Pretty neat. Now, just because these devices are really
quite simple doesn’t mean there isn’t room for innovation here. The biggest limitation with this standard
is that the car can’t really communicate with the charger other than to say “please provide power” and (rarely) “I need ventilation.” There really isn’t anything like negotiation
going on, and the charger is completely unaware of the characteristics of the car such as
its state of charge, battery capacity, or indeed maximum charging rate. That could be quite useful for things like
load sharing and potential back-feeding to the grid should that ever come to fruition. Let’s talk about load sharing because that
is a powerful tool for things like multi-family residential situations. Here, Tesla currently leads the way by quite
a margin. Load sharing allows a given circuit to provide
multiple vehicles with electricity by managing the current each vehicle can pull when more
than one is plugged in. Say you have a 40 amp circuit like this thing is on. Well, you could put all of the allowed 32
amps continuous into one charging station and thus one vehicle, but you could also share
that amongst multiple charging locations. See, a 40 amp circuit like what supplies this is capable of providing roughly 600 miles of driving range over a 24 hour period. But if you typically drive just 40 miles in a day,
you only need about 7% of that output on a typical day. Sharing it among multiple charge points allows for
more people access to one circuit at the same time. So long as the charge points can talk to each
other, they can simply command whatever vehicles are plugged into them to pull less current
so that it can be spread out between more vehicles. As individual vehicles are unplugged or finish
charging, they will allow the remaining vehicles to pull more current. Now this isn’t unique to Tesla but right now
Tesla has the most flexible and also most economical solution available through their quasi-proprietary wall connectors. Up to 16 gen 3 wall connectors can share a
single circuit and communicate with each other wirelessly, which greatly simplifies installation. While spreading even 60 amps (the max supported
by the wall connector) out between 16 cars leaves a paltry sum for each vehicle, the
idea isn’t really to allow 16 cars to charge at once - it’s to allow things like shared
parking lots or garages in multi-family dwellings to have more charging points with less capital
investment. It is very unlikely that all 16 units will
ever be in use at the same time, and Tesla has one other advantage up their sleeve here. Because Tesla is Tesla they’ll have absolutely no reservations about allowing direct communication between the cars and the wall connectors. It’s my understanding that the Tesla wall connectors
use the same protocol as SAE J1772 in the cable, they just use Tesla’s proprietary
connector rather than the real deal, so I don’t think they talk through the charge
cable itself. I’m absolutely certain I’ll be corrected
if I’m wrong so I won’t even bother asking. But the good thing is that this allows non-Tesla
vehicles to charge on a Tesla wall connector with an adapter. Thankfully. That’s why they’re not quite proprietary. Barely. But if Tesla vehicles can talk to each other
and also the network of wall connectors through some other means like WiFi, they can communicate their states of charge and rather than split the available current equally, it can be prioritized to vehicles with lower charge. From my perusal of the manual of the Gen3
wall connector it doesn’t look like this prioritization feature is currently live,
but of course there’s no reason to think it won’t be quite soon via a firmware update. Still though, similar solutions are available
from companies like ClipperCreek, and indeed inside this Siemens unit there are some connections which make me think it can be bonded to other units and even limit its charge rate based on a little potentiometer I saw in there but anyway those companies don’t have the advantage of vertical integration and so their products tend to be a little more expensive. That’s the downside of serving everybody
and not perpetuating a walled garden. Plus right now, there’s no codified state-of-charge
communication between car and EVSE. However, that could change. A proposed update to the SAE J1772 standard [through gritted teeth]
really would have been nice to have given it some sort of name, guys... would enable real vehicle-to-charger integration using power line communication protocols. That would help enable my personal EV charging
pipe dream. I would love for power utilities to start installing
their own level 2 EVSE equipment all over the place. Help get people in apartment buildings set up, and those who live in areas with on-street parking only. If the car can communicate with the EVSE,
and the EVSE is part of a smart grid, an EV driver can register their car, plug it in
anywhere on the network and have the electricity it uses automatically added to their own personal electric bill. Public charging today is a mess of competing
companies each trying to make a profit in one way or another, and maybe that’s where
we should go but personally I kinda wish utilities would just step in. Plus, if the car can tell the grid its state-of-charge,
dynamic load-balancing on a huge scale would be easy to implement without stranding drivers. And, should backfeeding of the car’s charge
to the grid ever be a thing, well that's a perfect way to make that happen. If you’re a policy maker and/or someone
who works for a utility, I’d just like to say I really think you oughta start looking
at this. If you had L2 chargers everywhere, you incentivize
people to keep their cars plugged in and if their cars are able to feed the grid in times of excess demand, well now you have access to battery storage which you didn’t need to pay for. And yes I know that idea is unsettling to many
people, but the beauty of a smart grid is that you could potentially offer incentives
and opt people in, or you could simply codify into vehicle design that every EV has a 10%
charge buffer that’s invisible to the driver. That way there's some battery capacity that they don't even know they have and never affects their range. There’s so much we could do, all it takes is some imagination and willingness to regulate some things. Which is obviously a pretty tough sell in the US
at present. But for now, your garden variety EVSE is a
pretty dumb device. Even Tesla’s wall connectors when installed individually really don't do anything more than this does. If I can give a piece of advice to those who
are in a situation where they can install their own charger in a private garage, it
would be this; have an electrician install a NEMA 6-50 receptacle. I installed this one myself, and yes I know
that needs to be in conduit-- I’m getting to it. Anyway, many EVSEs are available with this
plug, and they come in various capacities. It will allow effortless changes in the future,
and also offers some peace of mind in case your EVSE happens to develop a fault of some
kind and becomes unusable - then you can simply replace it yourself in mere moments. Though as I hope I’ve shown you, there really
isn’t much that can go wrong with these. It’s just a fancy light switch. Thanks for watching. I hope with this video I’ve explained that
this piece of the EV puzzle is actually quite simple. There’s a lot more we could do and in my
opinion should do to make EVs more feasible for more people, and to help leverage them
as much as possible. The real challenge is how to get EV charging
more accessible to renters, multi-family dwellings, and areas with street-parking only. Tesla deserves praise for their innovation
with the wall connector, but I do hope they will eventually join the rest of the automotive
industry and remove the dichotomy in North American charging standards that as of 2020 they alone are maintaining for a competitive advantage. I know, I can’t help myself here, but I
say that not necessarily to disparage Tesla but to let the less-familiar with the EV world know
that an industry standard charging protocol and connector exists for all vehicles not
made-by-Tesla. And also to get some of the more die-hard
Tesla fans to engage with that reality and what that might mean for the future adoption
of electric vehicles. Yes, you may wish to bring up that Tesla went
their own way because the standards we have now were not yet finalized, and they totally
should have! EVs wouldn’t be taken seriously were
it not for the Supercharger network. But a robust standard exists now that every
manufacturer has signed onto. They owe it not just to future Tesla owners
but also the industry as a whole to support it. And better do it now than later. Just for context, that little orange thing
below this charge port? That covers the high-power DC pins of this
CCS-combo connector. Again, every modern EV and plug-in hybrid
going back to 2010 except for Teslas has a J1772 connector, and by augmenting it with
these large DC pins, DC fast charging was added without removing compatibility with existing Level 1 and 2 AC infrastructure. Now that Nissan has dropped the competing
CHAdeMO from the US market, every new EV will soon have this exact plug or it will be a Tesla. And don’t tell Tesla loyalists but these
bigger pins which they often like to say make the connector needlessly bulky can handle
more current than Tesla's proprietary connector. If Tesla chooses to support CCS in the North
American market as they have already done in Europe and China, I will be so delighted I’ll make
a video about just that. But until that day, I will remain incredibly
annoyed at them for being the last remaining automaker holding onto a proprietary connector. That doesn’t help move electric vehicles
forward, it just helps Tesla. Anyway, let’s cut to black before I get
a mob on my hands. ♫ interoperably smooth jazz ♫ [various sounds of struggle] This isn't awkward at all... Up on top here to the left is a junction box which splits out tractshion [said a little weridly] This line is a tongue-twister! Oh my god I'm just looking at all those technical words that I wrote down there... [sighs] Great. But they go one step further because... oooh, skipped a line! That's exciting! But when a car is plugged in, just as there's a resistor on the EVSE seuh be dueh nuh enunciation failed a little bit. ...downside of serving everybody and not just - I should've - I didn't write, see the thing about the connections that are in here; I didn't write that in because I didn't open this 'till later. Is not where we're headed today either. Oh, shoot! Did you know it's really that simple? Did you know that the car is where the charger lies? Some of you undoubtedly did, but if this is news to ya I hope it makes you think more positively about the situation. It really isn't anywhere near as complicated as some people make it out to be. SUPPORT CCS, ELON!
Every single one of his videos are mealtime worthy, I've never had as much fun learning about how a CD changer works or why fans always start on high power, as I have watching these videos.
At first glance I thought the car on the left was a picture of earth from space.
I'm disinclined to watch 27+ minutes on this topic, and have a strong suspicion that someone is about to come along and explain how this video is being pedantic, and it really is a charger in the most accepted useage of the term...but I'll happily be wrong
What does your electric bill look like when you have an electric car?!
I giggled everytime he mentioned the load his Siemens charger was delivering. I am a child.