Electric Vehicle Charging and Cat Safety

Welcome to the macro fab engineering podcast. I'm your guest Christopher Howell.

And we are your hosts Parker

Dolman and Steven Craig.

This is episode 162. Two quick announcements before we jump into the podcast, key con 2019 is coming up soon. It is a user conference for a popular open source CAD program KY CAD. It is happening April 26 and 27th 2019 in Chicago, Illinois. This is the first and largest gathering of hardware developers using key CAD talks at the conference will span hardware design, revision control, scripting, manufacturing considerations and proper library management and getting started developing the underlying tools. All announced talks have been listed on the conference site which is in our show notes. Then the next announcement is Mac fab will be at South by Southwest and Austin this year, we are teaming up with particle.io to put together a hardware happy hour. It will take place this Friday, March 8 from 4pm to 8pm. At the jester King brewery, check the show notes for full details and to RSVP. Join us for food beer and network with fellow hardware engineers to kick off your South by Southwest weekend.

Open E V SC started in February 2011. With a simple experiment to try to generate the J 1772 pilot signal on an Arduino. One experiment led to another to another until a prototype J 1772. Compatible controller was born with lots of feedback and interest. A few boards were offered to other hardware hackers, what started as six boards built in the first batch turned into many 1000s. Today, open E V S E powers charging stations from many manufacturers all over the world.

So Chris, what is open E V? Sen, who are you?

So we are obviously an open source company. There was a problem in the industry charging stations were extremely expensive, and they were really just a glorified, very safe power cord. So we really wanted to drive the cost down and provide a product to the community that was more affordable and was cool, you know that you could hack you could do lots of cool things with

so hacking power cables,

absolutely

high powered car charging cables. That sounds like a really generally safe thing to hack, right?

Sure. Why not? 20 kilowatts, you know, just just a little bit.

So Chris, who are you though?

So I'm a network engineer by trade. I've always been interested in electronics. My grandfather was an amateur radio operator. And you know, we always played on the radio together and built circuits together. And I've always had an interest in electronics. This particular project came out of just desperation, really, I had a quote that was insanely expensive. And I just started playing around.

You know, I love the fact that you call it a project, even though like it's like a huge thing now like where you're offering kits and manufacturing stuff. I just I don't know, I that's a great thing. I love it. Yeah, it

started out as a project it I never intended for it to go where it went. But it's been a fantastic ride. I've really enjoyed every bit of it.

And so I guess it was because of the lack of open openness with car chargers is why you decided to get into this

correct, absolutely the at lack of openness, the lack of options. And, you know, the fact that everybody was was really being gouged at the time, the cost was just insanely expensive way more than it should have been.

So what, what makes this different than just like an extension cord, I guess is a good way to put it.

So there's a protocol. You mentioned it in the introduction, J 1772. And it's kind of a checks and balances. So you wouldn't want you know, just any average person playing with, you know, like I mentioned 20 kilowatts worth of power, energized at the end of a connector. So basically the standard ensures that there's no power available at the end of the connector until all of the safety parameters are met. So basically, it also tells the car how much power it may draw from the circuit, because the vehicle itself isn't going to know what's available. And that actually is a dynamic setting. So the Available Current can change depending on many different things you may have generation capability or solar availability you may want Want to alter your charge current at different times. So it provides a protocol to communicate from the station to the vehicle and the vehicle back to the station.

So if you're running off solar in a cloud rolls on over, your charger can say, hey, you know, you can't be so hungry?

Absolutely, we have a solar divert feature, where we partnered with another open source company in the UK, it's open energy monitor. So their energy monitor can measure the output of a solar and we can adjust the card charging to dynamically adjust to match what the solar production is at any given time.

So the the J 1772. Protocol, what all does that encompass? Is that just the signaling between things? Or is that more? It is

more than that. So it is the shape of the connector. It's the signaling and it's some of the safety features that are required. There are other safety features that are required by UL specifications as well.

So what kind of what kind of signal is it? Is it like TTL? Is it a serial connection isn't a common port.

Now, it's actually an analog connection. So what happens is, the charging station provides a 12 volt signal. And when you plug in the electric vehicle, it drops that 12 volt down to nine volts. When the vehicle is ready to charge, it drops it down further down to six volts. And that signals that the Charr the car is ready to take a charge.

Okay, so how does the communication between how much power the car can take and that kind of stuff happen?

So what happens is that same signal, once the charging station is ready, it turns on a PWM signal at one kilohertz. And the duty cycle is what specifies the current that's available. So you alter the duty cycle to change the Available Current at any given time.

That's a very interesting setup they have there.

Yeah, the fact that that it from the sound of it, it could all be done analog, like you don't necessarily have to have smarts behind it or, you know, the traditional sense of smarts. So I wonder why they decided to go with that.

Yeah, that's a good question. I think it's a, some fall back from history. From the older EVs back in the days of the Eevee. One, I think they had a similar setup back then. But it's also very simple to implement. You know, it does have its limitations. Of course, you can't pass any data from the vehicle to the charging station or the other way. But it is very simple to implement both on the vehicle side, and on the charging station side.

Some people might think that's actually a benefit not being able to transfer data, because of security reasons and stuff like that.

Well, it may be a benefit, for security reasons, but there are some really interesting things we'd like to know from the vehicle. For example, right now we have no idea the state of charge of the battery, we don't know if the battery is completely empty, or if the battery is completely full. So if we did have a data signal between we could at least know that the batteries say, you know, 68% charged, and then we can make decisions based on that. But since we have no idea how empty or full the battery is, we can do you know, we have limitations on on how fast we can charge or what kind of decisions we can make, since we have no clue what the state of charge of the battery is,

gotcha, or how impatient that driver is, there you

go. You have to be prepared at all times to deliver the full load, right?

You well, you have to be able to respect the pilot signal. So what happens is, say the if the pilot signal is saying, Hey, you have 16 amps available, it's the responsibility the vehicle never to exceed that. So you can change that on on many different many different inputs. For example, if you have demand response with your utility, we could reduce the pilot when there's an energy shortage. In the UK, they're actually going the opposite way the utilities are providing a incentive or a cheaper rate at certain times and we speed up the charge when the rates drop. So there's a lot of a lot of things you can do with a dynamic pilot signal to alter the speed at which your car is charging.

So besides the SAE J 1772. Is there any other kind of regulations that you have to kind of engineer around?

Yeah, then you have to, there are UL guidelines that dictate some of the safety features that that we have to implement. And basically this is a safety device. It's a very smart power cord and safety device. So really, you The number one focus has to always be safety. So every check that we do has a verification to it. Like for example, when we do ground fault testing, before, every time we close the relay, we check that we tickle it with a test coil just to make sure that the circuitry is working as expected. We also want to ensure that the relay is open when it's supposed to be open and closed when it's supposed to be closed. So we actually do stock contact detection to make sure that it really did open the circuit when it said we're supposed to open the circuit. So every safety feature has a verification along with it to ensure that all the systems are working correctly.

Cool, does the so the products that you provide this smart charger, do they have any any of the regulatory markings on him like the UL listing or anything of that sort,

the individual project the products and kits that we sell do not have UL listing on themselves. Basically, when you list a charging station, you list it as a whole device. There are companies that do use our products that do have UL Listed products. There's a company called Wat Zilla that builds their stations with our hardware and firmware. And they did go through the full UL testing for their charging station. So since really our target audience is manufacturers of stations and kit builders and enthusiast, we don't have you a listing on on those particular products. There's no way you Well, whatever certify a kit, they want to make sure it's built the right way in a factory that's that's certified, for sure. So some of our customers are UL certified that use our products, but the particular products we sell are not.

So the kids, I'm actually kind of curious about them. First of all, I want to ask, how much interest are you seeing in the kits? When it came when it comes to electric vehicles? My initial thought would be that someone would just want to buy whatever it is throw it up on the wall. And there you go, yeah, you're done, you know, but you you offer kits that are, you know, build it from the ground up. So how much interest are you having on that,

there's actually a quite a lot of interest in the kids, the early electric vehicle drivers were very technically minded people, we're starting to see a lot more of the general public by electric vehicles, where they're not going to want to put together a kit. But you know, there's definitely a lot of people out there that want to understand how their charging station works. They want to be able to repair it when it breaks. And if you buy something off the shelf, there's no way they're going to sell you a controller board or a contactor or even provide you with a schematic. So there are a lot of people that want to be able to repair their equipment and understand how their equipment works. So we've actually had really good success with the kids.

Yeah, actually, I've been doing a lot of research on, you know, eventually, maybe designing or building my own electric vehicle. And one of the big questions that comes up when doing that is like, how do you still charge it? And, you know, having an open source charging solution is one of those things.

Yeah, it's very helpful. And there's, you know, when a company wants to develop a product, it's a lot easier for them to buy our kit and then add their secret sauce on top of our foundation. So a lot of our kits sales do go to universities, they go to other manufacturers, they go to entrepreneurs who are trying to build something. So it really makes a great platform to start from if you had to design all the electronics from scratch just to get you to the point where you could develop your product that takes a lot longer. So we've seen a lot of companies that are very interested in our kits to advance and accelerate their projects.

For sure, so what what's included in the kits, what what if someone were to purchase a kit, what would what could they expect.

So in the kit itself, we include everything you need except for the AC cable and the J 1772 cable. It's all of the screws, all of the bolts, all of the electronics, all the wiring, and we've we've made a lot of a lot of improvements over the years. So now basically you can build a kit with just a screwdriver. All of the wires or harnesses that just plug right in there already the correct lengths. The electronics just screw in the firmware is already pre loaded. So basically if you can operate a screwdriver you could put together one of these kits. We also do sell bundles, which do include the electric vehicle cable as well. So literally you do Just put it together and slap it on the wall. You don't need any other components, or programmers or you don't even need to solder, no soldering no crimping, just just assemble it just follow our online build guides.

And these are intended to be plugged into a mains outlet somewhere nearby. Right?

Correct. We generally use the nema 1450 outlet, which is basically an RV outlet. They're found all over North America and campgrounds and and at home. They're very inexpensive to have installed on your property because they're very common with with our V's.

So I got a question with compatibility, because I know well, I think I know that like Tesla uses their own kind of thing, like on auto manufacturers that standard J 1772. Do they all adhere to that standard? Or are they different? Or and How do y'all handle that?

So all of the automakers do, including Tesla, Tesla just uses a different shape. So they include an adapter that adapts their special shape to the J 1772. shape. So all of the electronic compatibility is the same. And our charging stations are compatible with Tesla, as well as all the other modern vehicles, including vehicles overseas. There are other standards in Europe. One of them is called IEC type one and IEC type two and our controllers are also compatible with those as well.

So when is it just marketing when Tesla just says supercharger?

No, there superchargers are apps absolutely super, it's really incredible what the amount of power that they're putting through that very small connector. So their superchargers are really the best in the industry. And they're everywhere. So it makes long distance driving, very easy to do.

So what's the I guess compared to your charger? What makes that charger different from a technical standpoint, besides just more power?

Well, from a technical standpoint, what's happening is our charging station, really, you know, like we said was a smart power cord. The actual electronics that convert the AC to DC are onboard the vehicle. So the actual charger is on the vehicle. The Tesla Supercharger is a DC device. So it actually is the charger. It's an off board charger, basically, that's very, very high power. It takes the 480 volt three phase electricity, converts it to DC at very high power and then manages the battery as it puts the the energy into the vehicle.

Okay, gotcha. So it is actually almost fundamentally different kinds of charging mechanism. Absolutely.

There. Yeah, there's gotta be some more smarts behind that. I'm sure there's communication there.

Oh, yeah, absolutely. And they actually have digital communication on the DC quick chargers, they have a can type signaling, that's that's constantly sending data back and forth between the vehicle and the quick charger.

You know, out of curiosity, do you know how many of your users are Tesla drivers?

I don't know that answer. But I would guess that it would be in the 1000s. We have about a 15,000 plus installed stations at this point. All the way from the deserts of you know, Mojave, California out in the middle of Siberia.

So do you know anything about the going the other way, like I was talking about? If you were someone who is designing or building an electric vehicle, the battery management is a big deal. Do you know of anyone that's kind of working on that? That would work with this kind of standard?

Yeah, there's some open source work that's going on to decode some of the stuff that Tesla's doing actually, they're they're trying to replicate all of the different components within the Tesla battery and battery management system in an open source. fashion. I believe that's happening over in the UK.

Oh, cool. I'll have to take check that out.

There's always a you know, a very vibrant DIY community for just about everything having to do with electric vehicles. So whether you're building a battery or battery management system, or you're building your own charging systems, there's there's plenty out there in the in the open source and DIY communities.

Cool. So Steven, you want to go to the listener questions that we have

a real quick I want to just ask about the your energy system or program. I'm not entirely sure what to call it. This is this is some data management and gathering system on your charging Correct?

Yeah, so what we do is every 30 seconds we take current and power readings as well as temperature readings with inside the enclosure and we send them up to our server. This is another product of the open energy monitor. Project, they have a a application called eemaan. CMS. So basically, we're taking this data every 30 seconds and graphing, you know, the power over time, the temperature while you're charging, and as well as usage for each day. And here's some of the cool things you can do especially with with internal temperatures, you can start predicting failures, when the temperature rise is higher than you'd expect, you know that something's wrong there. There may be, you know, a loose connector, you know, something going on with the charging station.

So how are you actually reporting that data is it over Wi Fi is or something of that sort?

Yeah, our station has Wi Fi built into it. And it basically has a router type interface where you can log into it and change settings, you can set up session options like say, example, add five kilowatts before you stop charge for two hours. Or you can set up timers. If you have a different rates, you can say start charging at 11pm and stop charging at 6am to get the best rate. So within that Wi Fi interface, we we send the data to our eemaan CMS servers, if you choose to, you can also build the same thing. It's an open source project. So you could actually build a local server within your own house and never send any of your data out to the cloud. We give our users a choice.

That's really cool. Is that running on? Because I met Chris at the particle.io conference. Is it running off a particle was it photon?

It is not it's not running off a particle right now we're using an ESP 8266. Okay, and we will likely upgrade that in the future to an ESP 32. That's a project I'm working on right now. Whether or not we go the particle route. That's still under evaluation and discussion.

Cool. All right. So John Cutler have from Twitter asks, is there any work on allowing load sharing from multiple Evie SCS, sharing a circuit and or supporting the hydro style setup? So I'm going to guess what is the hydro style setup? If I guess if you know,

so, yeah, hydro was a project by one of open avsc early customers, a guy named Nick, great guy. And what he did was take a he basically built a splitter, so he regenerated the pilot signal twice, shared the current and half, and allows this little box to plug into one charging station and then charge two vehicles. So it was a pretty cool little setup he had, can you do that with open avsc, you can actually do that today, it just takes a little bit of work. Open avsc supports MQ TT messaging protocol. And if you have an MQ TT broker, as well as software, like Node red, for example, you can actually build whatever logic you want for charging your vehicle or sharing load, you know, you could increase charging based on positive Twitter sentiment, or you could decrease charging based on stock value of a certain company. So you could actually build any logic you can imagine with Node red, and then control the charging station with MQ TT. So that is possible today, we are working on ways to make this a lot easier for the user, so that you could just click a button and do the sharing. So yeah, we definitely have that as a upcoming feature, as well as you can do it today if you're willing to put in the work.

Um, he also has date based scheduling, which you've already explained, it already does that through the app. Yeah,

the current app, it basically all seven days of the week are the same. But the open energy monitor guys are working on a little plugin to their software, that will give you more granular schedule based so we will have more more complicated scheduling coming in the near future that can can pick out weekdays versus weekends and set multiple schedules and even take external inputs and schedule based on lowest rate or you know, whatever. Grid conditions are available at the time. So we do have some intelligent scheduling coming very soon.

Cool, and then smaller, more portable versions, but I'm looking at you got one on the wall, and I think that's pretty small.

Yeah, our current station is just about nine and a half pounds. So it's very small and portable. But we will be coming out with even smaller versions very soon. We did have a basic station a few years ago, that was basically the same station without the LCD display and a little bit more compact, compact. So we are going to reintroduce that in a different form factor fairly soon, and we may even go another form factor even smaller than that.

And I think more portable, it's like, I guess I'm imagining like a solar panel like, like opening up.

Yeah, I don't think we'll be doing that. That's a great idea. I'd love to see you know, solar panels and batteries on a trailer to charge stations and vehicles. That would be, that would be a pretty cool, well, I

need like 144, double A batteries.

Yeah, exactly. There was actually a guy that had a, I believe it was a Cadillac. And he puts a battery and a charging station in the back of the trunk. So he definitely had a portable charging station, he could drive it to wherever he needed it.

So the design in terms of making it more compact, I looked at your build guide earlier today. And correct me if I'm wrong, but it looks like a lot of the design was driven by the enclosure in a sense, where it seemed like the enclosure was picked, and then the electronics fit inside the enclosure. Because there's a little bit of extra room in there that could be shrunk a little.

Yeah, so we used a standard enclosure from a company called Polycase. They have a lot of different options and enclosures. And they do machining and printing on the enclosure. So that made a really good choice. The size was actually driven by the current. Since we're trying to do about 48 amps of current, we needed to have a relay that was large enough to support that. So really, the the end current is what's going to dictate the size of the station, we can get a 40 amp station a little bit smaller. And we can do a 24 amp station if we integrate everything on the controller board, like integrated relays as well. But we're limited to less than 30 amps if we go with smaller relays, so we can get it down in size. But we also have to shrink the power as well.

And then he also asks, is there a Raspberry Pi version coming soon?

We're not planning anything based on the Raspberry Pi. The guys in in the UK, the open energy monitor guys, they're playing around a little bit with with Raspberry Pi's and banana pies to throw in charging stations. But right now we're sticking with the ESP 32 and the 8266 for our comms.

Cool. And then guy Thomas, who is from our Slack channel, his handle is GRTYV are asks, what is the current state of the vehicle charging grid? And what can we do to influence decision makers to move faster on adoption? I have a response and as the five electric vehicles.

Yeah, that's that's a good one. So actually, the infrastructure is is doing very well. Tesla kind of set the standard with their Supercharger network, they build a nationwide network of quick chargers. And then they also have a program called destination Chargers were at hotels and resorts and places you might be staying for a lot longer, they've been putting in destination chargers. So if you own a Tesla, you can pretty much go anywhere in the United States without any problem at all, or any prior planning. Other manufacturers are having a little bit more difficulty. They built the vehicles and expected the networks to be built for them. That exactly didn't happen the way they hoped it would. So I think a lot of the manufacturers are starting to realize that, hey, you know, if we, if we want to have a nationwide network, we may have to build it ourselves or create a partnership to do that. home charging is very easy. There's really not much you have to do to prepare a home for charging. Basically, if you can throw in an RV outlet, you're good to go. If you have other power constraints, you can charge slower, but you have to make sure that you'll be able to add enough miles to match your daily commute in order to do that. And then around town, you know, I drive places and I'm surprised to find charging stations in places I had no idea where they were they were. So really the infrastructure is really coming along very nicely. And because electric vehicles are generally charged at nighttime, when energy is plentiful, they really aren't having any impact on the grid itself.

Isn't I think VW is being basically it's part of that diesel gate. ruling is there it was like five years ago for us to build. Well, the green force to build a start charging grid kind of thing.

Yeah, they are building a charging infrastructure and they've done some public service announcement advertisement as well as part of part of that diesel gate settlement. So hopefully a lot of good will come of that.

And then super capacitors for buses or trains. Is there any progress in that area?

I don't know about that. Now let's now see that that would be an interesting question probably for Elon Musk since Tesla was was trying to buy that super capacitor company. So he probably knows something that we don't. So I haven't even asked him right. I could try. I met him once, but he never returns my calls anymore.

Yeah, I think isn't that the future just doing having giant inductive coils? In the concrete slab in your garage? Right? So you just drive on top of it and your car just charges, right?

That would be a cool way to do it. You know, there are losses involved with that. But you know, really plugging a car into a charger is no big deal. You know, it's the same as your cell phone. You plug it in at the end of the day. And you know, you start the next morning, it's full ready to go. How long did it take to charge? I don't know. But it's it's ready to go in the morning.

Yeah, I can imagine if you had a an inductive charger, because inductive charges work really well, when your device, the coils are really close together. But you've got like, you know, five, six inches in a normal vehicle air gap. And think about if your cat went underneath there, and it came out the next day with three eyeballs. Or it just microwaved it.

Yeah, maybe that would happen.

20 kilowatts of inductive charging. Yeah, might that might happen.

So that's actually gonna be a listener. Question there is. Figure out if you like how big of an inductive charging you need to do 20 kilowatts.

Yeah, how many amps? You'd have to send into a giant coil to actually produce that at the at the load?

Well, that's not just load. It's also the the you have a loss there. Right. That's how I don't know what the inductive losses.

So I'm saying at the load you want, you want 20 kilowatt. So what do you have to dump into it to get there?

Yeah, that would be a lot.

Yeah. And is it cat safe? Okay, so I have one more question for you, Chris. Before we let you go. All right, what Evie, do you drive?

So I started out with a Nissan Leaf. And I still do have a Nissan Leaf. But I also have a Tesla Model S and my wife drives a Model X.

Okay. And what Evie would you suggest people to buy?

Well, my recommendation would probably be the Tesla Model three. It's a great car at a reasonable price. And really what sets it apart from everything else is the nationwide network that Tesla has built. All the other manufacturers are probably five, eight years behind if they decided to build a network today, and a lot of them aren't at this point. So really, that that sets Tesla apart is they have that nationwide network and it makes it so useful. You know, I haven't bought a drop of gas since December 13 2012. So I haven't bought gas in a very long time. And I've driven my car from Los Angeles to Bar Harbor, Maine, and back. So you really can go where you want to go. And you know, there's really no limitations these days.

And that's cool. So Chris Ware is gonna be the best place for people to learn more about you in open E V, S E.

So the best place to learn would be our website, open E vsc.com. We have a lot of information there. You can check out our source code on our GitHub repositories. Our build guides are linked and there's a store where you can buy components kits or even prebuilt stations.

Cool. Thank you for coming on to the podcast. All right.

No problem.

You got anything else? Stephen? No, I think I'm good. Hey, Chris, you want to sign us out?

I sure will. That was the microphone lab engineering podcast. I was your guest Christopher Howell.

And we're your hosts Parker Dolman. And Steven Craig later everyone

take it easy

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