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What's he building in there?

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  • brent012
    Frangipani
    • Feb 2011
    • 41

    Originally posted by mauswerkz View Post
    Embedded C is the reason I'm so comfortable with C ;-)

    There are 99 microcontrollers being used in that system (not kidding, one on each cell managing the cell's voltage during charging, and one polling the rest for their data and doing all the calculations). It's scalable up to 250 cells. The before/after picture is a shot of the serial stream coming directly from the main microcontroller. I've hooked an LCD up to it (simple 2x16 one) before and that's how it will be in the car for showing critical information (low cell voltage, high cell temperature, state of charge, etc).
    Ahh cool, so you'll have a pc in there for that display basically? Ever thought about using a cheap head unit from ebay/china which has windows ce on it for the display then? You'd have to use an older version of VB i'd say but it'd all work good as long as you could connect up an input from that main microcontroller, would be real easy to install in to the car as well then - but that's the least of your worries

    Lol sorry if what im saying is completely pointless or irrelevant, i don't know too much about electronics = ( I have an interest in it though and im starting uni this year doing ICT Engineering/Business though! Will be specialising in software but i still get to do some electrical engineering stuff and embedded systems too
    My N15 SSS Pulsar

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    • mauswerkz
      Electronical Stig / Moderator
      • Feb 2010
      • 1223

      Originally posted by tekkentool View Post
      Yikes! I knew EV batteries were expensive but damn. Even the DIY route isn't cheap.
      Yeah, they're pricey, but if they aren't abused, a modern EV battery should last 5-8yrs, which is about the same age you'd expect to start needing to do major work on any car. Also, the replacement battery in 5-8yrs will be half the cost and twice the capacity of the old one anyway.

      Regardless, I've done the math and taking into consideration the cost of the battery, the cost of electricity, and the cost of E10 petrol today, you'll break even on the cost of the battery if you drive an average of 44km/day (if the battery lasts 5yrs) or 28km/day (if the battery lasts 8yrs). Either of those numbers is reasonable. Luckily, the average distance per day and expected battery lifetime are linked, so if you drive less per day, the battery will last longer, and vise versa. I don't drive my car much at all. Maybe 2-3 days/yr, and my commute is only 10 minutes each way on days that I work, and I still manage an average of 29km/day according to my tracker app on my phone. Any driving beyond those averages ends up actually SAVING you money in the long run over fuel, and that's assuming you'll have to replace the battery.

      For example, if you maxed out the car's range every day (95km/day or so), assuming the battery would only last 5yrs, and that electricity will stay at $0.25/kw-hr and that petrol will stay at $1.40/l, you'd STILL save $38/wk over that period of time over driving a car that gets 10l/100km (even at 6l/100km, you still break even). That's almost $2000 saved per year. Over 5yrs, that's $10,000, enough to buy a new battery at today's prices. So the battery can potentially pay for itself.

      It's also safe to assume that both fuel and electricity prices will go up over that period, but it's more likely that fuel will go up at a faster rate. Throw in the fact that a modest investment in solar panels for your house pays itself off very quickly these days and an electric car suddenly doesn't seem as expensive.

      Okay, I'll stop preaching now ;-)
      My Facebook page - My YouTube channel - mauswerkz on Twitter
      The mauswerkz 300zx EV build thread.
      My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
      sigpic

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      • mauswerkz
        Electronical Stig / Moderator
        • Feb 2010
        • 1223

        Originally posted by brent012 View Post
        Ahh cool, so you'll have a pc in there for that display basically? Ever thought about using a cheap head unit from ebay/china which has windows ce on it for the display then? You'd have to use an older version of VB i'd say but it'd all work good as long as you could connect up an input from that main microcontroller, would be real easy to install in to the car as well then - but that's the least of your worries
        I'm planning to interface the battery management system and other key EV parameters/controls via either a carputer, or one of those chinese headunits running android (or infact any android tablet that the user wanted to mount in the dash for navigation, music, etc).

        Originally posted by brent012 View Post
        Lol sorry if what im saying is completely pointless or irrelevant, i don't know too much about electronics = ( I have an interest in it though and im starting uni this year doing ICT Engineering/Business though! Will be specialising in software but i still get to do some electrical engineering stuff and embedded systems too
        Congrats on starting uni! Software is fun, I think. Now that the hardware of my projects is mostly ironed out, the development is (and has been for a while now) all in software. There are many lines of code making everything work, talk, and play nicely (and not explode).
        My Facebook page - My YouTube channel - mauswerkz on Twitter
        The mauswerkz 300zx EV build thread.
        My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
        sigpic

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        • Rosey
          ain't no frangipani
          • May 2010
          • 6976

          28-1-12 last post? We can't have that..

          How's work on the EV-BMW going Mr Maus?

          Comment

          • mauswerkz
            Electronical Stig / Moderator
            • Feb 2010
            • 1223

            Originally posted by Rosey View Post
            28-1-12 last post? We can't have that..

            How's work on the EV-BMW going Mr Maus?
            Battery management system has managed a couple charges now, working fine. The controller is apart at the moment for a redesign of the capacitor precharge circuit. It's slow going at the moment due to Uni and stretching myself very thin with other commitments. It may see anothter surge in progress if thing come together for a solar race car at Uni. If my controller is in a state to be used in such a project, there may be some funding involved. For now though, studies and work take priority :-(
            My Facebook page - My YouTube channel - mauswerkz on Twitter
            The mauswerkz 300zx EV build thread.
            My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
            sigpic

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            • leadfoot
              feels indifferent about chrome
              • Nov 2011
              • 2546

              mauswerkz i too am a coder proficient in java, c, c++ assembly. i'd be keen to take a look at your code. i'm thinking of starting my own electrical project an integrated car management system. basically a carputer that replaces the ecu radio etc (think r35) the kicker being you'll be able to alter ecu settings on the fly. harnessing the power and calculation speed of a pc. the aim would be to replace the ecu with an interface module that connects to the pc viz usb or sata. i'd also be keen on your input/thoughts. i'm more comfortable with the code side of thing the pcb's aren't my cuppa tea
              the build it started as show and quickly turned into GO!

              Mitsubishi service and electrical manuals hosted by me for you mitsi nuts

              Originally posted by MOOG
              right next to my Silvia was an old Mitsubishi colt that had somehow managed to dodge the flames and was fine! absolutely perfect. every ugly panel of it. i could almost feel the Mitsubishi badge laughing at me and I've hated them ever since.

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              • mauswerkz
                Electronical Stig / Moderator
                • Feb 2010
                • 1223

                Originally posted by leadfoot View Post
                mauswerkz i too am a coder proficient in java, c, c++ assembly. i'd be keen to take a look at your code. i'm thinking of starting my own electrical project an integrated car management system. basically a carputer that replaces the ecu radio etc (think r35) the kicker being you'll be able to alter ecu settings on the fly. harnessing the power and calculation speed of a pc. the aim would be to replace the ecu with an interface module that connects to the pc viz usb or sata. i'd also be keen on your input/thoughts. i'm more comfortable with the code side of thing the pcb's aren't my cuppa tea
                Feel free to contact me in PM's on here. I've been planning to put some sort of graphical interface on my system since I started the design. I've got something like the Toyota Prius (or Tesla Model S if I wanted to go really advanced) interface. Something to show and control the main parameters of the drive system. I like the idea of having a computer control the engine of a normal car directly, but I doubt the speed would be there for effective control. I'd be more inclinded to have the computer control the parameters of a dedicated ECU, but have that ECU do the timing-critical work. This also protects against software/hardware crashes on the PC. I would certainly not use Windows. Anyway, we can chat more in IM if you like.
                My Facebook page - My YouTube channel - mauswerkz on Twitter
                The mauswerkz 300zx EV build thread.
                My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
                sigpic

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                • Harrstein
                  Frangipani
                  • Jun 2012
                  • 15

                  Bump

                  very interested in this project. as in about to do a study of electrical engineering. also quite interested in the battery part as my dad is quite in to this world. he designed batterypacks for electric bikes etc. all Li-ion ofc
                  How do I do English?

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                  • mauswerkz
                    Electronical Stig / Moderator
                    • Feb 2010
                    • 1223

                    Since this was bumped, I suppose I should post an update! I'm currently on break from Uni, but I've been so busy with other stuff that I haven't had a chance to get much done on this project. Thankfully, I was able to spend some time on it yesterday and (hopefully) have solved one of the problems I was having. The problem was how to charge the massive capacitor in the motor controller before closing the contactor (to avoid an arc between the contacts). This is normally done using a dedicated contactor which connects a resistor across the main contactor so the capacitor can charge gradually. Once the capacitor is charged, the main contactor can close and off you go.

                    The issue I was having was that I used relays to do this. It probably wouldn't have been a problem if I didn't want to both charge, and discharge the capacitor, which requires having both the positive and negative connected to the same relay. This means that nearly 400vdc was present the the same relay. Needless to say, I was having arcing issues. So I've designed the piece you see below. It's a solid state circuit which performs the same function. This is just the prototype and will allow me to get the controller running again. The final controller will have this built in, and I'm also planning on making them as stand alone units to sell to the EV community.



                    I've also purchased and modified a 3kw industrial variable speed drive so that it can run on my battery pack. This is connected to my second motor and will act to create a load when the first motor is connected to it. This way I can make a dyno for testing and tuning. Very handy to have!

                    My motor controller itself is going through a complete redesign at the moment. I wasn't happy with the 3-phase waveform generation algorithm that Atmel wrote and provided in an application note. I had to write my own code to perform dithering on the frequency so that the motor wouldn't jerk when the frequency suddenly jumped by 3-4Hz (due to the use of integer math in the microprocessor). I've written my own algorithm which is capable of up to 0.1Hz (+/- 0.7% of nominal throughout) precision for frequency and 2V precision in voltage. It also set the output duty cycle based on the measured battery voltage so that the output is consistent even when the battery voltage changes. Implementation of frequency control and slip will be much easier because frequency can be set directly as a variable, rather than using a scaled value as the application note did.

                    The biggest change though is that I'm moving to a much more powerful microprocessor which will support a ton of features that no other EV motor controller on the market offers and which I think even those of you who aren't in to electric cars will be able to appreciate. More on those once I've made some more progress and have something to show though.

                    I'm hoping to have the new hardware design compete and ready to order some PCBs by the end of my Uni break, but that only gives me two weeks to do it and I have other stuff I need to do in that time.
                    My Facebook page - My YouTube channel - mauswerkz on Twitter
                    The mauswerkz 300zx EV build thread.
                    My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
                    sigpic

                    Comment

                    • mauswerkz
                      Electronical Stig / Moderator
                      • Feb 2010
                      • 1223



                      New prototype motor controller board has arrived. Assembling and testing it one feature at a time. So far, so good! If all goes well, this board will actually end up in my car.
                      My Facebook page - My YouTube channel - mauswerkz on Twitter
                      The mauswerkz 300zx EV build thread.
                      My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
                      sigpic

                      Comment

                      • Rosey
                        ain't no frangipani
                        • May 2010
                        • 6976

                        That's awesome man, best of luck!

                        Comment

                        • Crazy2287
                          Frangipani
                          • Dec 2011
                          • 879

                          Fingers crossed! hoping it doesn't have any gremlins! good work and good luck!
                          My "show" (wan|<) car:
                          http://forums.mightycarmods.com/show...ing-(Car)Build.

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                          • AlexanderB
                            Frangipani
                            • Oct 2012
                            • 1072

                            Great project. Too bad they changed the rules here, the electric motor and controller both have to be "approved for road use".. So basically, you can now only build an EV if you buy a mega$$$ setup from Siemens or another company that does EV drive trains, or if you find a crashed, previously roadlegal EV and take the motor and controller from it...
                            Modifying is a lifestyle!
                            Originally posted by milkchicken
                            Oh man I hate it when the bolts on my car decide to strip, its so awkward.. I'm like dude I've got a partner I can't be seen doing this...

                            Comment

                            • mauswerkz
                              Electronical Stig / Moderator
                              • Feb 2010
                              • 1223

                              Originally posted by AlexanderB View Post
                              Great project. Too bad they changed the rules here, the electric motor and controller both have to be "approved for road use".. So basically, you can now only build an EV if you buy a mega$$$ setup from Siemens or another company that does EV drive trains, or if you find a crashed, previously roadlegal EV and take the motor and controller from it...
                              That's a shame. I'm surprised they'd discourage EV conversion like that. I think the US is about the easiest place to do a conversion, with very little oversight or rules regarding it (depending on the state). It's possible in Australia, but you have to convince a government recognized engineer that it's safe in order for it to be legal.
                              My Facebook page - My YouTube channel - mauswerkz on Twitter
                              The mauswerkz 300zx EV build thread.
                              My 1992 BMW 318is Coupe, soon to be battery powered. Technical progress in this thread.
                              sigpic

                              Comment

                              • AlexanderB
                                Frangipani
                                • Oct 2012
                                • 1072

                                I guess there is some tricks I can still try. get the part numbers from some 80's EV, print a nice label on the controller box and make a neat alloy plate on a similar sized electric motor.. Pretty bad cheat, but they probably can't prove you did not take it from that roadlegal 80's EV.. (Or, I you actually do find a rusted out 80's EV on the scrapyard, take the real bits, you can always put in a different controller and some extra volts on the pack when its registered. Same with engine swaps, they can't see the difference, nobody cares.)

                                The other one is frequently done on homebuilt kitcars, they are shipped to the UK where they have very lax rules about homebuilt and modified cars, and once you have it registered there, you can export it back to your own Euro country and by European law, its streetlegal everywhere in the EU because one of its member states approved. (If you tried to have it registered here, they basically tell you to build 3, and have 2 of them crash-tested.. :? unless its an engine swap, they're okay with that.. Except electric, apparently )

                                I haven't been able to find any data on EV conversions in the UK, and its probably not going to work, because the new rules here state "These technical requirements also apply to import cars." On the other hand, as soon as its legal in the UK, the motor and controller are now "from a roadlegal EV"
                                Modifying is a lifestyle!
                                Originally posted by milkchicken
                                Oh man I hate it when the bolts on my car decide to strip, its so awkward.. I'm like dude I've got a partner I can't be seen doing this...

                                Comment

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