A Simple, Overkill, Electric Car

If you’re building an electric car nowadays, you’re probably looking at taking a normal, gas-powered car and replacing the engine and transmission with an electric motor and batteries. [Gahaar] thought this is a rather dumb idea; all the excesses of an internal combustion-powered car, such as exhaust, cooling, differential, and fuel storage is completely unnecessary. Building a new electric car from the frame up is a vastly more efficient means of having your own electric car. So that’s what he did.

[Gahaar] build his new chassis around a single box made of 3mm aluminum sheet. Attached to this box are two AC induction motors at the rear of the car, negating the need for a differential, with 45 lithium cells stuffed into the middle of the box. There’s no gearbox here, greatly reducing the complexity of the build, and with the batteries providing 145V and 100Ah, this simple car has more than enough power for a lot of fun.

The suspension and steering were taken from a wrecked car, in this case a Mazda MX5, or Miata for those of us in North America. The Miata suspension easily unbolts from the frame of the wrecked car, and with just a little bit of welding can easily be attached to the new electric chassis.

Even though [Gahaar]’s car is basically just a bit of aluminum, motors, suspension, and batteries, he’s getting some awesome performance out of it; he estimates a top speed of 100mph with about 60 miles per charge. It’s an awesome way to get around the farm, and with a custom fiberglass body, we can easily see this being one of the coolest electric vehicles ever made.

47 thoughts on “A Simple, Overkill, Electric Car

    1. There are all flavor of VW’s that can accomplish this. I personally would find a Manx style buggy thats already registered and do the swap. Now only if I had the dedication or money that the submitter has.

    2. Yea. I don’t mean to suggest this as a reason not to do the hack but the nice part about an existing chassis is that an entire team of engineers studied it’s impact survive-ability and did exhaustive testing to confirm it.

      More importantly (for anyone who believes that their L33T driving skills will ensure that they’ll never have to rely on the impact survive-ability) tht same team of engineers also thoroughly studied and tested the frames capacity to not break over long periods of use and work-hardening…

    1. It has Mazda MX-5 suspension. It’s a sports car, so it doesn’t exactly have rock-crawling articulation and miles of suspension travel, but it’s actually pretty comfortable to ride in. Since this is presumably lighter than the Mazda, it’ll ride harder unless he changes out the springs, but still has more than enough travel for use on real roads.

        1. The miata is the Japanese version of the quintessential english sports car of old. Light nimble cars for twisting country roads. It might not be masculine enough for some, but I don’t see how the term for the car would change with the gender of the driver.

          On the actual topic, I have entertained the thought for some time of buying a light super seven replica and converting to electric drive train. I could probably be a very nice toy and would turn out something like the thing in the article, but with a body and basic safety.

          The obvious problem with super seven like ev cars is the barn-like air resistance, even with the small front area.

          1. Have a look at some of the full-body clones (no idea which continent you’re on so you may find this easier/harder depending upon it). Things like “Fisher Fury” and (Raw?) “Pheonix”, they both have a similar style of chassis as a 7 but with bodywork that covers the wheels and a bit more of an aerodynamic shape.

          2. (I’m replying to myself, Sheldons post didn’t have a reply-button)
            The problem with a fisher fury or a ginetta g20 or something similar is that they are harder to find and quite a bit more expensive. There is quite a lot (relative to the size of the market, that is) of (registered, road legal) sevens in different levels of sophistication to be had around here (sweden).

            I’m actually rebuilding the battery for my ev that I ride to work (when it works) right now (this is a break). But that is only a moped :P.

          3. That’s a shame. As I’m in the UK, while there are a lot of cheap 7 clones, the Fury/Ginetta/Pheonix cars are not that much more. I’ve been tempted to convert my own Fury (currently with a bike engine) to electric but I think it would be better in the long-run to just buy someone else’s failed project and work from there.
            Not knowing the exact costs, I guess the only other alternative for you would be to import one from the UK (I know “Vinnie” @ ‘C7 Imports’ over the border from you in Finland does this quite regularly – all be it mainly focussed on working 7s).

            Out of interest were you thinking of keeping the motor in the front (with propshaft to a rear-diff) or trying to Franken-hack it into the rear behind the seats where the fuel tank & diff are normally squeezed in (effectively directly dring the wheels)?
            I’ve wondered maybe something designed for rear-engine would be a better chassis such as the Sylva J16/R1ot or something more track-day focussed such as the SabreG2 from AB Performance.

          4. UK imports of sports cars are quite common, especially for people tracking them. Uk is significantly cheaper, if you don’t mind sitting on the wrong side of the car. Registration is a problem for cars without the proper eu-papers. Sweden has a system like uk for registrations of one-offs, but that don’t apply for cars you bought already built. Buying a kit from caterham and electrifying would probably work. The sane way to do it would probably be to monitor used cars sale-channels for a light space-frame covered car or a super-seven like one with a blown engine or as an almost-done-project and buy whatever the best thing is that shows up. I might be a bit tight in the back of a seven for a motor, maybe you can fit it on top of the diff with chain drive.

    2. You were probably looking for MacPhereson struts. It’s off a Miata so it’s Double Wishbones on all 4 corners. For on-road suspension for a small, light car it’d be hard to do much better as long as he’s in a similar weight range.

    1. No, he has it right. From the builders page “The chassis is one of the few items you need to fabricate. The majority of items are sourced and attached to the chassis. We use a pressed aluminium box from 3mm thick aluminium sheet that doubles as the main structural spine and the battery box. The approach keeps fabrication very simple, maximises rigidity, keeps the weight low down and concentrated in the centre of the car and keeps the battery pack away from damage in impacts.”

  1. I ESTIMATE my electric car does 200mph and has 1000 mile range.

    Doing some sort of measurement is not exactly hard is it?

    Also, I bet if you unbolted ALL the unused parts from an MX5 you’d get a lighter monocoque chassis with things like doors, windows, windscreen wipers ready installed.

    1. Entirely possible. There are reasons carmakers switched to unibodies, after all. Wasting weight on exhaust and differential is an odd complaint given that all that shit can come off.

      1. I don’t think that it would be lighter than this, but it would certainly be stronger.
        Backbone frames don’t have a lot of torsional rigidity, and they don’t handle offset impacts very well.

        1. There is a small company in the Czech Republic named “Tatra” that makes all-wheel drive trucks (plenty of vids on youtube) whose main trademark is a backbone frame made by a big friggin’ tube…

          That frame design has proven itself for the last 80 or so years, has very few equal rivals, because that tube allows for good stiffness, lots of suspension travel (swing axles) and a convenient place where to stash the driveshaft and differentials (all wheels are driven, 4×4, 6×6 or even 8×8)

  2. I’m not an engineer, however a stressed member like that even at 3mm thick of alu will have stress cracks real quick. He would have been better off using the monocoque of the miata, as for no diff? That’s a tough one to have as the electric motors would need to be synced when going straight and compensate in revs and load in corners. Masochistic fun to be had to a very simple solution. The diff itself is not as inefficient as the chains hes using to transmit power to each wheel, and requires way less maintenance, he could have used the motors mated to each-other down the middle with a diff in the front, with ford Festiva spindles and an inverted diff having a true mid engined, 4wd vehicle with a locked center diff, or insert a diff in between the two motors.

    1. It’s really no problem to control electric motors for rpm and torque to eliminate the diff. Think of the control of the 4 (!) motors in a quadcopter and the flight figures you can do this way.
      You can even combine this with inertial sensors (accelerometers and gyros) to make any kind of ESP and torque vectoring you want. So it is a much better solution to have individual motors you can control individually. It is just not possible or economical with internal combustion engines in the size of a normal car. So the diff is the second best solution.

  3. As the designer and builder of the car I can provide some responses to these comments.
    Strength and stiffness – a large diameter thin walled tube has better performance than the typical unitary body construction. A Miata is not a monocoque. A race car monocoque is a large thin walled tube that you sit in. Check out the structure of the Lotus Elan or the Tesla Roadster if you doubt me.

    Suspension – with this platform the springs sat on their bump stops, so yes had to swap out for much softer springs.

    Weight – I unbolted every thing from the Miata frame before taking it to the dump. I did not weight the frame but it was too heavy for two people to lift but it could be rolled easily by two people, so would estimate over 200kg, compared to the box chassis which could easily be lifted by one person, less than 40kg.

    Speed – haven’t tested top speed because I don’t have access to a test track and the speed is far greater than I can test on the dirt roads around the farm.

    Safety – This is not intended to replace your family SUV. Its more about a fun weekend, track, farm or for an electric platform for a kit car body. It is safer than a motorbike or quad bike and would have a roll cage and body for the track.

    I would hope to inspire you with the simplicity of an electric drive systems and keep the focus on the engineering of a electric vehicle platform by presenting the project without it body which would draw the focus to how it looks and whether people like the styling rather than the underlying engineering concept.

  4. @ganhaar Wow, fantastic job, and I agree 100% with your engineering concepts themselves, but I have a feeling you’re going to run into registration / insurance issues unless you can prove that it really is an existing car. Good luck with it, I wish the best!! My 17 year old son will find this very fascinating, I’ll show him your page as soon as he’s home from school. We’ve had many discussions on the subject of designing a car from the ground up vs modding an existing one.

    Excellent choice of avoiding styling before the engineering is done! You’re a man after my own heart there. BTW you should probably put bumpers on it, or anything you collide with is going to come join you right there in the front seat.

  5. If he gets 60 miles to the charge, that thing competes with conventional designs…
    On a fraction of the time, budget, and manpower…
    Either he’s wrong about something or car companies just don’t give a fuck about electric vehicles.

  6. Instructable!!?? Seriously??!!

    If you’re smart enough to build this thing, I’m sure you’re smart enough to know that instructables is for kiddies blinking LEDs, not real projects like these. Please just post it all on some forum or something like that in the future if you don’t have your own website.

    1. You can use induction motors as generators. They need a way to get their rotor magnetized. The simplest way are some capacitors. Or you do it like Tesla does it: By the correct control of the drive inverter. Yes, Tesla uses induction motors and of course they do regenerative braking.

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