Electric Sonett: Old Car/New Tech

This project focuses on ecological sustainability and social responsibility through reuse. Increasing lifecycle efficiency, decreasing cost.

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I'm doing an electric conversion on a 1974 Saab Sonett. First, I'm restoring the car. More importantly I'm making custom mounts and adapter plate for a used Smart Car motor/controller to power the rig. I'm also using the 3.3 kW battery charger from the same era Smart Car. If I can successfully hack the Electric Smart Car system to use in this car, I will have effectively created a relatively inexpensive EV. Everything, including the car, cost me less than $3,000 (batteries not included). Batteries are the expensive part now, but their price is dropping.
My goals for this project are focused on creating an ecologically sustainable and socially responsible electric car (with the style/power of a 70s sports car). By building this EV from used parts I am saving money and extending the lifecycle of these components. By lowering the initial costs, people with less money can still invest in owning an electric vehicle, reducing fuel/maintenance costs and improving lifestyl

I am using an electric Smart Car motor/controller and charger, as well as some big relays, safety cut offs, crash switch and the water pump from the same era electric Smart Cars. I think there is great potential for the use of OEM parts in electric conversions. These parts are incredibly cheep. I purchased the motor/controller for $250.00 plus shipping. This reduces costs without reducing quality. These are really nice parts and will make for a powerful and dependable EV. The largest hurdle to overcome is hacking the motor/controller and charger (that's why it's so cheep). These components are controlled with proprietary CAN data that I need to get my hands on.

Despite this major difficulty that I may or may not be able to overcome, the ideas that I am exploring are valid/interesting/constructive. If I can't hack it, someone else soon will.

The ideas that fuel this project are centered on ecological sustainability and social responsibility. Utilizing used parts is good for everyone! It saves money and keeps old stuff out of the waste stream. It feels like dumpster diving for gold. But this stuff is around. Damaged EVs go to the junkyard with lots of good parts in them. As the proliferation of EVs grows, more parts will be available, so let's make use of them!

Ok, I'm rambling. This will be a cool project. Stay tuned and I will post CAD files of the adapter plate that you can modify to fit your transmission if you want to use this motor! Contact EV West, they might still have some of these on hand.

This project has taken an unexpected turn recently. I'm temporarily using a forklift motor and an old Kelly controller. Hopefully I'll be able to go back to the smart car system (I really want to be liquid-cooled) but for now I'm making some compromises to fit a schedule and budget.


Front Crossmember cut to fit Smart Car controller

JPEG Image - 1.33 MB - 12/30/2015 at 21:52



Stock transmission bell housing

JPEG Image - 2.45 MB - 12/30/2015 at 21:52



CAD (cardboard aided design) (I'll learn solid works soon)

JPEG Image - 1.88 MB - 12/30/2015 at 21:52



Cutting the transmission input shaft for prototyping purposes. I will make a custom shaft eventually.

JPEG Image - 1.86 MB - 12/30/2015 at 21:51



Sonett interior

JPEG Image - 1.37 MB - 12/30/2015 at 21:51


View all 22 files

  • 1 × Electric Smart Car Motor/Controller This is a used motor/controller from the Electric Smart fortwo.
  • 1 × Electric Smart Car battery charger
  • 1 × Electric Smart Car water pump Pump for coolant to motor/controller/charger
  • 1 × Electric Smart Car switches, disconnects etc... Relays, Emergency cut off, crash disconnect switch
  • 1 × Saab Sonett Transmission A free transmission from a junkyard.

View all 8 components

  • Getting back to it

    Adam Curtis09/28/2016 at 00:38 2 comments

    After a lot of traveling around I'm back in town and ready to work on the Electric Sonett some more.

    I have all the parts I need to get some tests going and maybe take the car around the block.

    look for more posts as I wire up the controller and batteries!

  • How I design

    Adam Curtis04/23/2016 at 23:22 0 comments

    Designing for this project required many different approaches. Sometimes it was easy enough to take measurements, design the part in question and make it according to those dimensions. Other times it would be exceedingly difficult to measure all aspects of a situation in order to obtain correct angles and placement. In these cases I often use a more fluid design and prototyping method. In the case of the battery mounts I decided that I would have the weight of the batteries resting on a couple reinforced spots on the battery pack and make several tabs that bolt to the car body as well. In this case I decided that the easiest way would be to make all of the hardware that I imagined needing and then spot weld everything in its correct place while the actual batteries were holding the space they would eventually occupy.

    I like to use technology to help in this process. The Notes app on my phone can integrate pictures, text and drawings into a single document, which is easy to follow.

    Here is an example of one way in which I prototype in the physical world.

    Battery mounting hardware


    Two tabs with hole offset up


    (Having completed these tabs I give it a check mark while working in the shop)

    Image.jpegMount to this surface. Triangle and tab


    Make triangle mount


    Weld nut onto car, bolt through tab

    Make beefy steel pieces that mimic motor mount shape and bell housing shape to weld to sheet lining under battery sides. These sheet pieces welded to original tray. Maybe 20 gauge on the sheet with 12 or 14 gauge strip between two "pressure points"

    The sheets need to be

    11" x 20"

    And 11" x 24"

    Cut out 4 pieces of 12 or 14 Gauge measuring 4" x 4"

    Motor piece


    3/4 from top 1/2" slot


    7.25" on top

    With these notes I was able to fabricate all these little parts quickly and efficiently. I returned to the garage where the car is and rested everything where it would go. After making sure everything still fit right I started tack welding everything in place. I use compressed air to cool a weld quickly when it is close to combustible material. The batteries are insulated in a thick plastic housing so I was not worries about welding near them.

  • Trunk Floor Replacement

    Adam Curtis04/23/2016 at 23:21 0 comments

    I just finished cleaning up the old rusty metal where the trunk used to be and tacking in the new trunk floor that I made the other day. Not to much to share. I will add a couple cross braces for support as my trunk has no structural bends stamped into it.


  • Throttle Pedal

    Adam Curtis04/23/2016 at 23:20 0 comments

    Over the last couple days I've figured out where I want the throttle pedal. I'm using a toyota prius hall effect sensor pedal. So this pedal takes 5v from a power supply and then sends out a 0-5 volt signal to the controller depending on position. I'm going to set up a "hot pedal" regen brake system. This means the regenerative braking will kick in as soon as I start taking my foot off the "gas" pedal and even before I hit the brakes. I've heard that the Tesla model S has this setup and people like it a lot. I've heard people say that it is worse for your efficiency because you don't coast. Maybe, but the amount of energy used to spin the motor at the same speed as the drive wheels is probably only around 200 watts or less, which (although not a good thing) is pretty small compared with the 16,000 watt hour battery pack. I will monitor the motor as I start testing the car and if it seems that the free-spin draw is excessively high, I will switch over to the standard regenerative braking activated by the brake pedal. This will allow me to coast without any draw on the battery pack.


    To set up the throttle pedal, first I made an aluminum mount in the approximate shape that I would need. I cut it across the front so I could bend it at the bend in the firewall of the car. I bolted the aluminum where I wanted the pedal. Then I duct taped the pedal to the aluminum mount and tested using it. It turned out that it was too close to the brake pedal and I kept bumping it when "emergency" stepping on the brake.


    Next I modified the aluminum mount so that I could move the pedal over to the right slightly. I TIG welded the aluminum at the angle that I wanted it and bolted the pedal to it.


    In this final position I was no longer bumping the throttle while hitting the brake and the throttle was comfortable on my foot at all angles.


    Voila! I still have to hook up the wiring and run it to the controller, but the mount is solid and I like how it feels.

  • Fitting it in the Engine Bay.

    Adam Curtis04/19/2016 at 01:54 0 comments

    Because of weight distribution problems and lack of storage space I decided to try and fit two of my three battery modules in the engine bay instead of the trunk (The smaller two modules.. 30s3p and 18s3p modules) This was immediately impossible because of my motor mount. I modified the mount so it would take up less space and now I'm back at trying to get everything into the engine bay. I successfully bolted the batteries to the modified (cut up) battery tray (the huge T shaped ones that the chevy volt is famous for). I cut that up into three parts so my three modules will all be bolted separately.

    I think I've figured out how the batteries will fit in the engine bay. Now I'm concerned about air-flow around the heat sink on my controller. This is an old Kelly controller (apparently they are infamous for over-heating issues). I'm not worried about the batteries over-heating because I will have them wired 24s 12p which means that each cell is supplying less than 8.33% of the maximum 500 amps the controller is rated at. Doing the math shows that each cell will be asked for no more than 41.67 amps at peak draw. For some reference the 2011 Chevy volt is rated at 149 horse power, which is equivalent to 111.1kW. The Chevy volt battery pack is rated at 360 nominal volts and actually operates between 300 and 400 volts depending on the state of charge and engine load. Let's do the math with 360 volts because that's nominal voltage.

    power (watts) = volts * amps. So 111.1kW=111,100 W = 360 V * amps

    That gives us about 310 amps peak draw on a 96s3p battery pack so each cell can provide just over 100 amps with proper cooling. I don't have proper cooling yet, but I plan to. But as long as I keep the load on the batteries to half of the original I'm probably fine. Right? Any smart people who know better, please tell me before I blow up.

    IMG_2033.jpgHere's the batteries resting in the engine bay above the motor and transmission. See any problems? I'll make a metal battery mount that bolts into the engine bay and tranny/engine mounts.


    I can fit the bonnet over the batteries but there is not quite enough room for the heat sink on top of the controller. The controller will either melt or self-limit without a heat sink. What if I put the heat sink through the hood? Is that blasphemy?


    Should I cut a hole in the hood for the heat sink or just leave the hood off until I figure out a liquid cooling option? IMG_2041

    What do you think about the aesthetics of this? Maybe I could get a scoop...

  • Front Axles

    Adam Curtis04/19/2016 at 01:15 0 comments

    I pulled the front axles out to put new rubber boots over the CV joints in the front wheels. YOU DON'T NEED TO DO THIS. THE RUBBER BOOTS FIT OVER THE T-DRIVERS! Anyway, I learned that after I had already broken a circlip (C-clip) in this case the stop-ring that keeps the axels from going too far into the CV joint. I talked to my friend Patrick who let me look through his Sonett parts bins but no luck. I talked to Chris and he had a couple, plus an extra lock ring (a thinner ring that keeps the axle in). I drove out to Worcester and picked them up. Getting the axles back in was harder than getting them out (which was as easy as hooking a ratchet strap to the T-drivers and pulling the axle straight out of the wheel hub). I broke one lock ring and had to use the extra. Getting the axles back in is easy if you do one thing. MAKE SURE THE LOCK RING IS BENT TO THE SMALLEST CIRCLE IT CAN BE AND STILL GET IT ONTO THE AXLE. Once I figured this out it was as easy as hammering the axles back into the CV joints. Before I figured that out I was trying to get the lock ring pushed into the CV joint while the diameter of the lock ring was greater than the diameter of the splines on the axle. This meant that the CV joint was pushing part of the lock ring over the outside of the spline instead of into the grove where it is supposed to live. I greased everything first and my dad cleaned and greased the needle bearings in the T-drivers (every one) (Thanks again to Chris for extra needle bearings, I was one short somehow...)

    I now have it all back together and dropped the motor/transmission in. I even hooked up a 12v power supply to the motor and let that drive the car forward.

    The drive train is all set up and working!IMG_1973.jpg

    This is the stop-ring. The lock ring is made of a wire. A tip for getting these lock rings on is use a small round file in the gap to make gripping it with a spreader easier. My spreaders have round pins for teeth and the flat ends of this clip didn't work well.

  • Revisiting the Smart motor

    Adam Curtis04/14/2016 at 14:03 0 comments

    So as you know from thoroughly reading each one of my blog posts to date... Just kidding, no one does that. I'll just tell you.

    I've TEMPORARILY set aside my smart car motor and controller until the software hack is complete. In the meantime I am using a forklift motor and an old Kelly controller. This is a simpler system and much less amazing in lots of ways but the motor spins, which is good.

    There's the background. Here's the update.

    I'm working with a friend of mine at Worcester Polytechnic Institute to get a custom transmission input shaft made with a spline for the smart car motor. He and I drew it up in SolidWorks based on measurements that I'd taken from the Sonett transmission input shaft and the female splines on the smart car motor.

    Just the other day he 3d printed the first prototype to check dimensions. It fits! He is going to machine the next prototype and then we're going with chromoly or something equally awesome. IMG_1971.jpg

    Here is the shaft in the smart car motor. In order to 3D print it he had to make it in four pieces but it seems to be fitting great!


  • Machining the input shaft

    Adam Curtis04/13/2016 at 04:17 0 comments

    Along with working on my battery pack I machined the splines onto my transmission input shaft today.

    I'm not 100% sure this will hold up to abuses but it will get me going until I can afford to have a rod of chromoly CNCed into a permanent solution.

    After drawing up the splines that I needed to make to fit my adapter coupling I found that the angle between splines was a perfect 90 so I just used a flat end mill and cut with the corner at just the right height and depth while my shaft was in the indexing head on the Bridgeport table. There were conveniently 20 splines and the indexing head is a 40 to 1 ration so I'd cut a spline, swing the arm twice and repeat.

    I cut these splines into metal that my friend and welder protoge Rhett Courser laid onto the shaft with his magical TIG skills.

    Here are pictures so you can understand what I'm talking about.

  • Chevy Volt battery pack tear down

    Adam Curtis04/13/2016 at 03:58 0 comments


    Today I got a battery pack out of a 2011 Chevy Volt with 50,000 miles on it. Let's hope their pack lives up to their 100,000 mile guarantee. It should as the car software is designed never to use the bottom end of the pack's capacity, which keeps it in a very stable voltage range.

    I'm going to take the pack apart and rewire the cells into a 148 volt configuration, which I will charge with the PFC-2500 from Elcon. This is a 2.5kW charger so the charge times are going to be abysmal but it's all I can afford right now.

    {{EDIT* 4/14/16

    Last night I opened up each sub-pack to discover that the cells are spot welded together in sub-sub-packs of 3p12s and 3p6s. There are seven packs of 3p12s and two packs of 3p6s. I can't unweld them so I need to work with a voltage that can be accommodated by these packs. Also, I want to use all of the cells so they age at the same rate and I can reconfigure them later into a 360 volt pack once more. That means my only two options are 90volts or 180volts. I'm using (temporarily) an old Kelly controller that can't handle any more than 178 PEAK voltage so I have to run the 90 volt system until I can go back to the Smart car controller. This will be a slow car. }}

    Here are some pictures of the inside of a Chevy Volt battery pack from 2011.

    I took all the buss bars off to disconnect the four sub-packs before I went deeper.

    The orange cables/plugs that go into the top of the batteries have cell level connectivity. So it should be pretty easy to put my own BMS on these batteries using those plugs!

    I'll post more pictures soon of what is under these plastic covers. The battery cells are welded together. That's going to pose problems when I try to take them apart to rewire them.

    {{EDIT 4/14/16

    Sure enough. There's no way I'm getting those cells apart. Check out these pictures and descriptions of the Chevy Volt battery pack...

    Here are the cells. Above are two sub-sub-packs of 36 cells (3p12s) and an 18 cell on the right (3p6s) You can see where they're connected with bus bars.

    Check out these sweet spot welds... damn.

    These huge bricks are held together with glue, steel bands and 3 foot screws. I wanted to see what the cooling system was like so I started taking this apart down to cell level. As soon as I loosed the 4 bolts that hold the black endplates together coolant started leaking out from every cell. Here's what the 4 bolts look like.

    Here you can see the four bolts coming off to the left and you can see that all of the cells in the module are spreading apart and spilling coolant on the floor. More detail below.

    Each cell has little o ring gaskets to seal the coolant inside.

    After letting the cells separate I had to use a ratchet strap to pull the module back together before I could get the bolts back in.

    Here are the three packs as they come off of the T-shaped metal plate. I don't have a picture of the hardware that holts them in place. It is a bar on each on at the base that bolts down and clams these plastic cell housings to the metal plate.

    Now I'm stuck with the task of figuring out where these modules can fit in my car... woof. The biggest one is 33.5 inches long. My trunk could hold that one I guess. The next larges is nearly that long with the coolant pipes coming off each end. I think I can fit that under the hood above the motor. The small pack will just go in the passenger's lap.

  • A quick switcheroo

    Adam Curtis04/12/2016 at 16:24 0 comments

    I've been trying to set up the Electric Sonett with a smart car motor and controller. I'm putting that idea on hold because I'm graduating in three weeks and I want to drive it down the isle to receive my diploma. Instead I'm temporarily going low tech. I'm talking brushed DC forklift motor with upgraded brushes. Kelly controller 144 volt 500 amps. Used Chevy Volt battery pack rewired to deliver! Still need to figure out the charger situation. I want a Manzanita PFC40XM but it's not quite in the budget. We'll see what I can come up with.

    I built the hardware to hold the motor in place over the weekend. Adapter plate and engine mount. I'm going to cob together an adapter between the motor and tranny driveshafts.

    This junk will probably only be safe up to 40mph, but it's quick, dirty, and a lot of fun!

View all 21 project logs

Enjoy this project?



Dr. Cockroach wrote 10/29/2017 at 22:40 point

Awesome project. I want to tackle a EV conversion and am just at the stage of reading as much as I can.

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edward19141914 wrote 05/11/2016 at 14:07 point


Did you have a control board replacing the one in zytek moter yet?

I am interested in using zytek 55kw motor for my mini bus conversion.

Your help for controller will be much appreciated

  Are you sure? yes | no

Adam Curtis wrote 05/12/2016 at 17:44 point

Hi! No, there is no replacement board or software yet. I will definitely make a post about that when it happens. 

Stay tuned,


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Matej wrote 03/23/2016 at 06:41 point

Why are you attempting to hack the controller/inverter versus just reusing whatever necessary bits from the Smart, if I may ask?

I am curious because I have also been eyeing wrecked Smart ED's and wondering what the bare necessities for using the motor would be. If all that is necessary to make it work is the accelerator pedal, I would be thrilled. Of course, I assume the battery pack would need to be of the same voltage as the original in the Smart, with a standalone 12V DC-DC system and a custom charger setup.

Are you trying to hack it in order to be able to take full advantage of all the on-board PDU functions, with the ability to reprogram it for different battery pack sizes and such?

Or do the Smart ED components use authentication similar to the Nissan Leaf, where the only way to make it work is to use nearly the entire electrical system from the donor car? Understandably, this would make hacking it the only option, since tracking down the car that the motor was pulled out of would be very inconvenient if not impossible.

Either way, I look forward to any progress you make with the motor and controller.

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Adam Curtis wrote 03/23/2016 at 16:48 point

Hi Matej,

Thanks for the interest!

So far as I understand it, the controller receives data through a CAN network and will only operate if it is satisfied that the other core components are working correctly. These cars are being decommissioned, but you can't buy a whole car because of legal reasons, so you can't just use all the parts (would be nice)... this makes the components undesirable and therefore very very cheep. 

I've found some folks who are working on a software hack of the controller. This would be the most useful for everyone because it will be cheep and easy to implement on many of these controllers.

Other options include replacement of the controller for an of-the-shelf one or just replacing the part of the controller that deals with the incoming signals. 

This controller has a build in DC-DC converter, is liquid cooled, and fits perfectly in my engine bay, so I want to use it if I can. 

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Jarrod wrote 01/30/2016 at 06:05 point

Hi Adam. I've been eyeing off the Zytek motor from EVwest too for a mitsubishi eclipse conversion, wondering how the CAN bus hacking is going? Were you able to get much info out of EVWest or Zytek themselves? did you seriously get it for $250? they are asking $900 now! (still seems like a good deal)

Another option is to keep the power electronics (IGBT's, drivers, current sensors and capacitors) but replace the microcontroller. This guy has made a universal inverter hacking board in fact he was linked from hackaday, hacking a Tesla inverter/motor

Actually uses the same chip I've been playing with in my 'everywhereElectric' ebike motor controller project on Great thing about this TI instaspin solution is it'l work with 3-phase AC motor, induction or PM, and any output stage so long as you have at least 2 phase current sensors.

Software is pretty well documented and super easy to customize if you are fluent in C++ and embedded systems. Also, I may be attempting it if I end up buying one of these motors. I'm in Portland OR btw.

Oh and what did you end up doing about the motor shaft spline adapter?

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Adam Curtis wrote 01/30/2016 at 15:06 point

Hey Jarrod, that sounds like a cool project!

I've met a couple guys who have the wiring diagrams from Mercedes and are working on the zytek system now (This weekend actually! I'll let you know about that). Also, EV West is working on it too. One of the main people, John, told me that they have succeeded in getting the motor to spin but nothing further. 

I like the idea of replacing the control board and keeping the high voltage stuff. Having taken the cover off of the controller I can say that there is plenty of room, everything is pretty accessible and modifications would be doable. I think it's a well-build system, and simple. There is some question about how much current the controller can handle. It is definitely the limiting factor, not the motor. 

All three phase wires have current sensors. 

I've been redesigning the motor shaft in SolidWorks. (I'll make the file available). I know some guys with a 5 axis mill so hopefully they can just set up the tooling and do it. Otherwise I'm going to be making it on an old South Bend lathe and a Bridgeport for the time being.  So I'm going to have a direct driveshaft from the motor into the transmission. No adapters or clutch. 

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Jarrod wrote 01/30/2016 at 19:58 point

Nice, sounds like it's close. definitely make a post on the process, I'd be fascinated!

Do you know what IGBT modules they use?

The company where I'm working is likely getting into high efficiency motor inverters in the near future, so I'm already thinking about bumping up the voltage, monitoring the motor temps and see what it'l do.

Wow so the motor shaft is not that hard to remove? I'd love to see some internal pics!

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Adam Curtis wrote 01/31/2016 at 00:06 point


Very cool. I'm not sure about the type of IGBT. 
The shaft I'm talking about is the transmission input shaft. It will mate to the female motor shaft. I won't actually be modifying the motor at all. 

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Jarrod wrote 01/31/2016 at 23:41 point

Transmission input shaft eh? does yours have gears machined into it? 5 axis mill should do it I guess.

I'm thinking I might be able to machine down my existing input shaft to fit the smaller splined motor shaft. 

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Adam Curtis wrote 02/15/2016 at 15:11 point

The shaft has 6 splines on the transmission side. The Zytek motor has 17 female splines so I'm going to make a ≈9inch shaft with bearing press fit surface in the middle, 6 male splines on one end and 17 male on the other. I'm only nervous because I had a really hard time taking measurements inside the female zytek motor shaft. 

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Saabman wrote 01/11/2016 at 04:41 point

hey Adam awesome car to convert.

I'd love to do a similar thing but Sonnets are like hens teeth in Australia. 

Just a thought on your transmission considerations - 

The smart transmission and engine are designed to go together. So I would think ditching the dead saab tranny and using the Smart tranny and joining the drive shafts would be the better way to go. As long as the shafts are in the vicinity of where you need them. 

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Adam Curtis wrote 01/11/2016 at 15:53 point

Thanks for weighing in Bernie,

I was leaning towards ditching the old tranny too, but two things have made a Sonett transmission more appealing. 

1) The motor mounts sideways to the smart car tranny which would mean not enough space in the engine by unless I take the controller off of the motor and relocate it somewhere else. The controller is so inextricably mounted to the motor that this option becomes daunting. They share the same liquid cooling build into the cast aluminum and the controller has a great case that seals perfectly to the motor as well.   

2) I've made a new friend who has about a dozen Sonett transmissions. 

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miscrms wrote 01/05/2016 at 01:30 point

Awesome project!  I'm in the process of transplanting a Leaf drive system into a '73 Sonett.  I ended up with the car that Jack Ashcraft had worked on about 5-6 yrs ago, which had originally been converted to a 96V DC electric drive back in the early 90's by Budd Clark with the help of Walter Kern.

Most of my work so far has been on getting up to speed on the Leaf drive system, but I'm finally getting to work on the Sonett.  I have two main threads going on DIYelectriccar for my build and Leaf experiments if you're interested in checking them out.

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Adam Curtis wrote 01/05/2016 at 23:13 point

Hey Rob,

Your project looks sweet! Is that the famous electric Norseman? Do you still have to flash the high beams at every stop to get the motor to stop quickly so you can shift down to first again? I'm excited that you reached out to me, thanks. I'm also excited to follow your progress on diyelectriccar. 

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miscrms wrote 01/06/2016 at 00:56 point

That's the one!  By the time it reached me the system had been rewired 2 more times, and half the lead acid batteries were on their last legs.  It was very innovative for its time, but the drive system was pretty out dated by today's standards.  With the lead pack it was probably pushing 2500lbs and even with the 5sp retained the 6" 11.6hp motor really struggled.  Switching to the drive system from the Leaf, I should be under 2000 lbs (hopefully close to 1800 lb stock weight) and with 80kw (~240 ft/lb, ~105hp at the wheels) it should be a lot of fun.  And with 1/2 the weight and 1/2 the CdA of the original Leaf, efficiency and range should be quite impressive too.

Its kind of fun to think that the original designer of the conversion, Walter Kern of Saab Quantum fame, was said to have two favorite cars.  His electric Sonett daily driver, and his Budd Clark built turbo Sonett.  If I can bring the performance of the turbo and the efficiency of the electric together in this one Sonett, I can't think of a better tribute to a Saab legend.

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saab96 wrote 12/31/2015 at 17:53 point

Ashcraft has a booklet on how to convert a Snett III to Sonett II style flip hood. He also does transmission rebuilds.

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Adam Curtis wrote 01/03/2016 at 16:06 point

Thanks, for the link. I'm in contact with Jack Ashcraft about his electric Sonett now and have lots of cool ideas from that.

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Adam Curtis wrote 11/19/2015 at 16:34 point

So, I'm well on my way developing the adapter plate for my motor to the Sonett transmission. I'm running into the problem that the transmission shaft and the motor shaft are too long and are keeping the motor and transmission too far apart. I cut the transmission shaft down to the bare minimum with enough spline left, but the problem persists because my motor mounting surface is not flush with the face of the motor, but actually two inches down the motor body.

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Adam Curtis wrote 01/30/2016 at 15:08 point

I've bypassed this problem by committing to making a custom input shaft for the transmission that will couple to the female Zytek motor shaft. Now I choose the dimensions. 

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Londubh wrote 11/10/2015 at 21:20 point

I strongly recommend you check in at

There are a few folks there who're working on EV conversions of sonetts, and there are likely some folks who're working with Smart parts, too.  You might also see if the guys at EVWest can give you any pointers, since they've got some Smart EV parts on their website and therefore might have some understanding of how they work.

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Adam Curtis wrote 11/12/2015 at 18:41 point

Thanks! I'll look into it. 

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Jeff Powell wrote 11/09/2015 at 20:37 point

Up here in the Monadnock area, we've got a lot of Sonett love going on. Used to have one, passed it on. I still have some parts though. Let me know if you're interested. And say hi to Josiah!

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Adam Curtis wrote 11/10/2015 at 04:40 point

Thanks Jeff! I appreciate the offer. I would love to take a trip up to the Monadnock area some time. I haven't been up in a while.

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Patrick wrote 11/09/2015 at 20:03 point

 Hi Adam--have you checked out the electric Sonett material by Eric Kriss? He has an excellent documentation of what he did at the time, with an earlier model Sonett V4. Good luck with the project. Cant wait to see you tooling around town next summer!

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Adam Curtis wrote 11/10/2015 at 04:38 point

Yes! You left the booklet in the car and it made it all the way to me!
Thanks for the support!

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Adam Curtis wrote 11/09/2015 at 19:29 point

I have a battery question. I'm hoping to run my system on about 370 volts. It needs to deliver about 180 amps peak and the voltage sag shouldn't go below 300 volts. I want 55kW. 

The question: What are your favorite batteries? Company?

My thoughts: I'm looking into a bunch of different batteries, they all have there pros and cons. I could make a pack from 18650 cells that could handle this load at that voltage but the pack might take me a long time to build. 

Since my voltage is so high I need a lot of cells in series. I don't have enough money to then run more in parallel so most of the bigger cells like the ones from CALB are out. 

EAS Electric Autosports sells a large cell that can do 300 amps peak but with the BMS it would cost over $8,000 for a 14kWh pack. 

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Adam Curtis wrote 01/30/2016 at 15:11 point

I want to go with used Tesla packs from the same era Smart Car. They are about $1000 a piece and I need 6. Time for fund raising! 

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saab96 wrote 11/08/2015 at 10:30 point

Will you use the Sonett's freewheel transmission?

It has been done before; not with OEM Smart parts though.

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Adam Curtis wrote 11/09/2015 at 19:16 point

I have been contemplating this decision a lot. I will either use the Sonett's original transmission and make an adapter plate for the motor, or I will use the Smart car transmission and mate the Smart Car axels to my Sonett's axels. 
Thoughts? I'd love to hear some opinions. 

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saab96 wrote 11/09/2015 at 19:36 point

This is how it has been done before, Sonett tranny with adapter plate & electric DC motor,  no need to change the front wheel suspension.

With this the Sonett will go 160 km/h (100 M/h)  @5500 rpm in 4th gear..

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David Holt wrote 11/06/2015 at 18:10 point

I have a friend in Topeka, KS who has 2 Sonets.  He doesn't drive them much because one or both have will be down with motor problems.  Converting them to electric drive would be awesome.  

They really are extremely light. I helped him move one of them up against the wall of his garage.  I could almost pick up the back of it all by my self.

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Adam Curtis wrote 11/09/2015 at 19:18 point

Haha! Yeah, I have to push my Sonett up a steep hill everyday from the storage area to the shop and I only need a little help to get it there. 

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zakqwy wrote 11/06/2015 at 15:53 point

Sonetts are great! Excellent choice for an EV conversion. What are your plans for the restoration? I saw some rust in one picture--are you going to do extensive metal replacement?

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Adam Curtis wrote 11/06/2015 at 16:17 point

Yeah, the Sonett is great. All fiberglass body, no power steering or braking needed and the empty unibody weighs in about 550kg. I've been doing extensive metal replacement. I'm making a complete new floor for the trunk right now. I'm also tackling the Smart Car parts. They use proprietary technology so it's going to be a bear to get them to cooperate.

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