I THINK – THEREFORE I CAN

I got this week’s video up more or less on time. But a blog entry just didn’t happen. Christmas came early in the week. It’s Friday and we face another show deadline. And I just haven’t gotten to it.

John Hardy requested a CAN tutorial and I made a weak stab at it in this weeks show. I’m guessing this kind of chalk talk is not going to get me to my dream of 100 million hits on YouTube and Susan Boyle type fame. Pacing to and fro in front of a green wall just can’t make good video.

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But CAN is as CAN does. And I am a bit excited about it. We are working on a project, for example, using the TCCH charger. This charger has become the default charger for EV’s largely on price. We have now a pretty good supply of a truly excellent charger, the Brusa NLG513 and even some interest from Brusa in our becoming a dealer. The problem is their pricing. Our cost would be about $2800 and I don’t think it represents a good value proposition even at that level. At the $1995 we are selling the AZD stuff, it’s a great one as it is configurable to an extreme beyond all need, and the build quality is just excellent. It’s also heroically small for what it does – physically. It’s easy to tuck into a car.

We also have the PulsaR in the wings. I was supposed to have 10 of these in stock by November 15. The first working prototype actually isn’t in test yet. But the task turned into an engineering challenge, and I’m told the THREE now PCBoards are off to assembly this week. Should have one in test soon. And hopefully we’ll get one shortly after.

My hope is for PulsaR to rock our world. It does feature CAN communications. And it has the opportunity to perform a lot of instrumentation functions as it manages power INTO the battery pack as well as out of it. It will give us a hugely capable AC charge rate of up to 100Amps and 3 phase if you have it. And of course it does DC charging as well. In this way, we can do charging at up to 300 amps and 370volts from a “mother bank” or another car. That positions us for SAE J1772 Rev B Level 1 and II DC charging.

And I think that does offer a good value proposition at $3500.

Back to the TCCH charger. These have been going for $1200 or $1400 in the 4kw range. At 130 volts, that is 30 amps and gets a 180Ah pack in the black in 6 hours. It’s a little largish. But bang for the buck, this charger from China has been the low cost alternative.

It has a little problem. IT’s not configurable. So you order it with a set voltage, and if you’re pack changes or upgrades, you get to do it OVER again. There have been some versions sorta/kinda available that do 10 charge curves separated by a volt or two to get a range. And you kind of have to pick a voltage range when ordering to maximize your current at that voltage.

For another $75 they sell a CAN controlled version as well. So like U.S. OEMS, they have foregone confirmability for CAN control. Now the ball is in your court, do whatever you like with it. It comes with a little CAN adapter with two pins – CAN HIGH and CAN LOW and there is a bit of a specification. But it really doesn’t amount to a great deal.

When you turn the charger on, it starts transmitting a CAN message indicating the current output voltage (0) and the current output current (0) and a status byte where each bit indicates a fault. If it doesn’t get a reply within about 5 seconds, it shuts down.

It expects a very simple CAN message in reply. The CAN control message has two bytes for VOLTAGE and two bytes for CURRENT and one byte for CONTROL. The CONTROL byte basically let’s you keep the charger ON (1) or OFF (0). Whatever current level you send it, it will try to charge at that current level (up to whats available) until reaching the commanded VOLTAGE. When it reaches that voltage, it automatically tapers the current to hold it.

And so we have been working with Nathan Knappenburger on a little Arduino project to control the TCCH charger. He’s been at it since August, and this week I started looking into the code a bit myself as he seemed to be in some dire straits over something or another.

Enter Macchina. Macchina is the Italian word for “Machine” and serves as a vernacular for automobile in Italian. The Macchina is a specialized board by RechargeCar based on the Arduino Mega 2560 and is compatible with all 5 OBD2 signaling protocols including PWM, VPW, ISO 9141-2, KWP and CAN. Actually most specifically CAN using the MCP 2515 CAN controller and the TJA1051/TH8056 Transceiver. This should cover any car built from 1996 onward. It includes a sturdy power supply to power sub-circuits and add-ons (called “shields” in the Arduino world) and was designed with automotive standards in mind on a 4-layer PCB with better immunity from Electromagnetic Interference (EMI). The MACCHINA SCHEMATIC

Better, on the ATMEL 2560 used in the Arduino Mega, there are six external hardware interrupts connected. And so the Arduino documentation shows how you can attach a function to a an external hardware interrupt and trigger it on a rising edge, a falling edge, or on a change. These are denoted as interrupts 0 through 5. Interestingly enough, the Arduino source code actually supports interrupts 0-7 for eight total hardware interrupts. It’s just that two aren’t connected to anything, and so they don’t document this.

But Macchina connects the pin 13 interrupt output of the MCP2515 CAN controller chip to the hardware interrupt 6 pin on the Atmel 2560 multicontroller. This has an interesting effect. You can use this hardware interrupt to do CAN in a very efficient manner, and it can’t interfere with any shields that use hardware interrupts because it isn’t normally connected on the Arduino version. But it IS supported in the standard Arduino compiler.

The MCP2515 has another feature to recommend it. It features 2 masks and 6 filters that allows you to mask/filter for messages from specific CAN IDs. In this way, it will ONLY set an interrupt when messages from IDs that get through the mask/filter table arrive. This feature is not actually implemented in the Arduino library RechargeCar has provided. But we discussed it with them and they are going to add it to the library. This is very powerful. In this way, you can “listen” for only messages from devices you want to interact with. And better, with the hardware interrupt, you don’t really have to listen at all. When a message from such a device shows up on the bus, the MCP2515 will put it in a register and assert an interrupt to call up a specific routine in your program to deal iwth it. The rest of your program can operate for all intents and purposes without interruption, so to speak, on other things.

Relieving the ATMEL from having to actively “listen” for messages is a dramatic reduction in workload. So we’re gradually becoming a bit of a fan of the MACCHINA.

Chargers have long been a problem for EV builders. With this, we will ultimately have a line of three different chargers with very different capabilities and power levels, at three different price points. But ALL three of them will be CAN capable.

Controller Area Network (CAN) goes quite beyond the Generalized Vehicle Control Unit (GEVCU) we have proposed. It is going to be a part of everything we do on an EV build in the future. I believe we can make this as inexpensive and easy as the old RS-232 serial port was for modems and online services twenty years ago. And it promises much easier integration with modern vehicles as conversion donor candidates, and the use of OEM parts in our builds.

Jack Rickard

54 thoughts on “I THINK – THEREFORE I CAN”

  1. Hi Jack,
    I rarely post here, but I read the blog, comments, and forums religiously. I just wanted to say that I very much appreciated your explanation this week about CAN structure. In fact, just the previous evening I had been perusing wikipedia articles looking up terms that I didn’t understand on the forums, so your chalk talk was very timely for me.

    Of course, Just when I thought I had a handle on what it took to do a conversion, along comes this discussion of CAN and it’s importance to converting modern cars. I’ve avoided the need to learn about CAN and the myriad of associated knowledge (networking, programming, etc), and have also avoided looking at donor cars that depended on CAN for full operability. IF (and it’s a big IF) I can get my head around this new direction that you’re pushing for, it should open up many more possibilities for conversions for me. I don’t mean to speak for anyone else, but there may be others like me who have also been limited in donor selection due to unfamiliarity with automobile systems like CAN.

    Thanks again for moving the rock a little further,
    Alex

  2. Jack,
    Thank you for the “Chalk Talk”. It seems that, just when I think I understand these beasts, I realize that the layer of understanding I have is nowhere near the core (or the Whole). And, I’ve been troubleshooting and repairing these (OEM) systems for the last 20 years!
    But, I guess that is the difference between repairing an existing system and creating a new system.

    I still have a lot to learn…..
    Keep up the good work,
    Raul

    1. Thank you for the finer details of CANBUS Jack. Most rewarding.

      Was shocked and saddened when I saw no “return” glassed in around the bottom edges of the wheel arches to both stiffen and make safe from catching pedestrians. For what it is. It’s cheap!

      I have a question.
      Say joe Blogs has a big switch mode power supply of the correct voltage for his proposed pack to give ≤3.35V/cell. If his theoretical supply had a current limiter so the Voltage dropped if the load was too high. would it make a viable system?

  3. Hi Jack,
    I use two 2KW TCCH chargers, which I mounted where the fuel tanks used to be in my Mazda MX5. They are 416V chargers which gives me 3.65V/cell. I no longer allow them to get to 416V, instead, as soon as the voltage reaches 400V (3.5V/cell) I drop the current to 3amps (C/20) which drops the voltage, and switch off when the voltage gets back to 400V. This gets around the need to change chargers when the voltage requirements change.
    Also using the Gridconnect CAN-232 interface is a quick and inexpensive way for experimenters with RS232 experience to communicate with CAN devices, including the TCCH chargers.

  4. Re: 28 Dec show… forklift idea for Richard. Since there are already electric forklifts, there’s no need to do an ELETRIC conversion. But, how many are LiFePo4 powered? You could do a “hot rod mod lift” show using CALB cells, more power, better instrumentation, more power, faster charging, and more power. It could be used as a mobile fast charge power supply as well as a load for testing stuff.

    Just a thought 🙂
    Raul

  5. Jack, your approach for CANBUS is awesome. Attacking the problem of modern car being computerized instead of circumventing it.
    May I suggest you setting up a Wiki for collecting information of various CAN message types for various cars? That way multiple people can put their findings in one place without the risk of losing anything.
    Wiki is much better for collecting knowledge than forums that are best for questions/answers kind of stuff.
    You can use public Wiki platform, like wikia.com or set up MediaWiki on your site.

  6. Jack,
    Just a heads up on the Honda Insight picture. The one that appears is not the ground breaking first generation one, but the horrible “transport unit” that replaced it.

  7. For those who are not fit enough for programming complete hardware like Macchina or
    other Arduino derivates…..but want to do some tests or research in CAN I can recommend
    the combination of the Lawicel-232 CAN-RS232-Adaptor and the freeware CANHACKER.
    Of course, Canhacker is not like some a little bit more professional Software like Labview,
    but it is free and very easy to understand.
    The thing i missed most is the ability to decode a message to its bits, but it is a good base for beginning.
    It allows You to listen and write and even to filter CAN-Signals without expensive devices.
    for a few predefined CAN-Messages, the bandwidth will be enough, and all the dialoges
    can be easily programmed as RS232-Messages with a little Atmega and BASCOM for example.

    I had been successful in listenig to the CAN-Bus of a SMART Fortwo with the Lawicel Adaptor.
    The SMART is a wonderful example for a vehicle that has almost everything based on CAN.

  8. I quite enjoyed the segment on the AutoBlockAmp in the Dec 28th video. During the calibration phase does the “-” need to be entered in front of the calibration value? At 1:01:42 in the video the graph appears to show -51.1 amperes. Does entering 50.2 instead of -50.2 send the unit into chaos? I will be adding one of these units to my equipment list for my project.

    1. Does it make any sense to toggle the fuel guage into being a tachometer as well? It’s not like in an ice where you are trying to hit shift points, but more of an rpm indicator. The fuel guage/tach coul have a toggle switch to change function. You hardly need either one to be dedicated to that function full time.

  9. Something serious to say about these shootings.
    The root issue, Nigh on all of those shooters AND the many, many suicides are down to taking SSRI’s. Stressed soldiers in Afghanistan are killing themselves faster than the Taliban can. A few have walked out and killed whole villages. None of these killers are autistic kids.
    Then there are the civilians. The USA is by far the worse. 10% of the people are taking them but if you miss or stop…. Beware! How you feel is not natural.
    Please Google “suicides shootings SSRI”. Perusing Youtube will also give many first hand accounts who were on them, how it affected them and what the users done. Also users who were attempting to cold turkey after being on them. Horrible!

    On a lighter note. Richard, you are beginning to remind me of Darth Vader.

      1. In regard to Heating system control, I had some not yet tested ideas that I’ve been considering. Jack is correct in that normal relays will weld closed or fail to extinguish the arc when opened when operated at high DC voltages. The EV200, tyco and gigavac contactors are great but they still have limited capability to close into a load. I am only guessing that is what happened on the escalade. My idea is to develop a heater controller based on an 8 pin PIC or other microcontroller. Use a couple inputs for low, medium and high inputs from the fan switch, or an analog temp selector or whatever. Use one output to pick up the EV200. Use a second output to energize a solid state relay, like the one here: http://www.crydom.com/en/Products/Catalog/s_sc.pdf
        The solid state relay could then be PWM (I’m thinking 50-500Hz or so) operated to supply varying amounts of power to the heater element. In that way too, and most importantly, the solid state relay would only turn on AFTER the EV200 closed. The EV200 would then be commanded to open AFTER the solid state relay is commanded to turn off. In that way the mechanical contactor is never opening or closing under load. All this is theoretical, and it seems like a good idea to me, add disclaimer here….

        Brian

      2. Richards beard reminded me of Dark Invader ;). Don’t worry Richard, you look ok.
        You must excuse me. I’m not a smoker and my niece asked me if I’d like to try her e-cig; strawberry flavour with high nicotine. I was so high they had to hold on to my ankles and this friend of hers was building a Leggo VW micro bus and helped by sticking flowers on it..

        A fine old pair of Teletubbies that drink whiskey, play with high voltages then go for a drive. A program for real adults. Not much chance of Jacks Nu-nu doing its stuff at 6am on a Sunday morning though.

  10. Great show again this week. I’m just a little curious. Is Brian ever coming back? Did he decide to hang it up, quit the rat race and run away to join the circus. The weekly show after all was his idea.

    1. Haven’t heard from him. The show was my idea. Brian wanted me to do it WEEKLY and claimed he could sell ads if I did. He didn’t. But it was a nice thought. I sold a few. But it was difficult. Particularly the Chinese.

      In any event, he will undoubtedly be back. He’s worked for me five times now. Over 17 years. But it’s not all fun working for Jack. It’s kind of addicting, but not always fun. At the heart of every successful entrepreneurial activity is in overcontrolling detail obsessed neurotic asshole driving everyone to distraction. If you don’t know who that person is, it is YOU. In the case of EVTV, we all know who it is.

      In any event, if he doesn’t want to play anymore, he doesn’t want to play. But I would expect him to show up right about THE most inconvenient time. That’s the pattern.

      Jack Rickard

  11. If the use of CAN bus becomes straight forward things are going to change. New equipment will come into the scene and mastering its control will only be a keyboard away. For example the 2005 V50 Volvo uses a nice electric power steering pump with an internal VFD that is CAN bus controlled. Even without CAN bus the unit will operate at a default speed with only 3 wires. I have installed one in my Miata project and someday would like to included CAN bus control on the amount of power assist. The search for the CAN ID and instruction format continues…

    1. I wonder if these new rules will apply to bicycles?

      I believe that the UK government considered the idea for EVs and rejected it, but it would be just like the EU to introduce such a rule. Without wishing to speak ill of the absent, it has been some years since the EU’s auditors have been able to sign off the accounts so the risk of malfeasance is greater than it might have been otherwise.

    2. Agree, it should be applied to all cars or no cars. Every time I’m walking in a parking lot with a car behind me that is petrol, I think about this stupid law.

  12. I do a lot of bicycling in the urban environment and lots of ICE vehicles sneak up on me. In setting such a president, they also need to put strobes on any vehicle that is on and in gear for deaf people.

  13. Is there anyone who knows how many different Litum based batteries on the market
    in the perspective to the quality as a function of price, quality, performance.

    Best Regards Allan

  14. As time goes by I am warming up to Richard. He might not be a master sommelier but he’s got a knack for seeing the practicality of things, which is a good balance for Jack’s technical deep dives. I’m even warming up to Richards way with words and enjoy his occasional “antidotal” stories. But this week I discovered I have to draw the line at “Massatoosits”.

  15. How about a review or stocktake of the various builds (and purchases) and a discussion of the choices and compromises of each so the in one session there is an appraisal of the successes and difficulties of each option and what is to be learned from each example. For example the Mini Cooper is hardly mentioned. Is this a car you still want to drive? Would you make the same choices if you were converting the Mini Cooper starting today?

    The aim would be to give a sort of how we got to here in the journey of building electric car conversions and then an assessment of how good here is. Of course, as we know in quantum mechanics, here may actually be more than one place. As string theory tells us, here may have several strands.

  16. While attending EVCCON-I I remember being struck (no pun intended) by the fact that I was watching 30 some odd cars simultaneously moving around the tarmac without a sound. I then imagined what it would be like to be in downtown Chicago with every car being electric. You might even be able to have a conversation on the street. Now try to imagine a crowded city with every car being electric and making some stupid electronic sound at the same time. The streets will start to sound like an arcade game. We will start to long for the good old days when it was all just really loud white noise.

      1. Doc:

        I build my own EVSE and only used four wires; the AC service wires and the pilot signal wire; the proximity wire wasn’t needed. see the following Open Source EVSE site to build your own: http://code.google.com/p/open-evse/

        BTW, There were 10 cable assemblies for sale; the guy sold seven then raised the price to $125…greed at work!

        Ladson

        1. Or maybe supply and demand. I ordered one to look at it. But I doubt I would use it for much. We got some of those 70A models recently and that’s what we have in the store. The 30’s are probably plenty, but I don’t want any. I’ve even refused my GE Wattstation to do 45a.

          My Escalade can draw about 65 amps. And we don’t have a PulsaR yet.

          Jack Rickard

        1. John,

          The question is, what system would reliably detect such a condition (loose connector heating)?

          Perhaps a simple temperature monitor that would always disconnect the traction pack when temperature in the battery box is not within limits would probably take care of this as well as prevent charging in unsuitable conditions.

          Cell level BMS is hardly the solution for this particular problem anyway. If any.

          1. Yes I guess that a loose connection on the cell might also further trash the attempts by any BMS to manage SoC by monitoring voltage (I have a voltage trace on my latest test pack which appears to show this)

  17. The WallStreet Journal is reporting the fire was caused by wiring. But, this discussion raises a question: Just how do you put out a Li Ion battery fire? Can you extinguish it with chemicals? Do you let it burn out in a safe container?, flood it with halon? a sand bucket? What safeguards and procedures are in place aboard an aircraft in case someone’s PC or cell phone catches fire?

    Ladson

    1. Going open source has advantages. Tinkerers, modders, tuners, 3rd party market and free advice and idea’s off the public being fed back to the manufacturer.
      On the other hand…. The police, given a Fascist remit can obtain access to see if you have been speeding, where you have been and the routes taken. Whether you stopped at the stop junction, tuned the car after the emmisions test and so forth.
      Ugly.

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