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Discussion Starter · #1 ·
Well, with three and a half estimated months left to finish my build, it’s about time I start a build thread, complete with pictures for the eye-candy addicts. :)

Here’s my car, a 1990 Honda CRX. Ain’t he a gem? Yes, I said he. As my wife always says, he is a stick shift. I got him last summer, and we named him C-Rex.



When we got him, he had 3” lowering springs on him and it would bottom out on every bump in the road. I replaced those with a 1 ½” lowering, with increased spring stiffness performance coils for better handling (and anticipating a slightly heavier endcar, even with lithiums). I also found a nice set of Enkei rims that are just a touch scuffed up – when the conversion’s finished I plan to repaint them pearl silver. The rest of the car will also be receiving a paint job after the electric conversion is finished, new windshield, new rubber moldings, etc. What, you don’t like cancerous sunspots on the top of your roof?

Although this is a build thread and not a blog, people often ask me why I am bothering with all this, so I thought I’d say it once. I’m converting my car because I want the U.S. to be less reliant on foreign oil. Will my car make a difference? I don’t kid myself. But slowly the country is turning its eyes to electric and I hope to be one of the early users. Additionally, I was born and raised in the Motor City, and cars are a huge part of my life. Being an electrical engineer as well, it’s the perfect blend of interests to make a great (and expensive) hobby. My goal for the car is to be fast, fun to drive, practical range, and intuitive to use. I want any of my friends to be able to borrow the car and not have to explain “well, just click that lever three times to prime the pump… and you can’t use the heat while you’re using valet mode…” or whatever. The car HAS to have an intuitive OEM look and feel or the American public will never want one.

But they will want a C-Rex…
 

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Discussion Starter · #2 ·
Fast forward six months. My little sister has been driving C-Rex for several months now (since her car died). She must have bad car luck or something because C-Rex died and there was oil in the spark plugs. I took that as a sign – the EV conversion would now begin!

And by “conversion” I mean several more months of saving money for the build and finishing other projects around the house before starting another headache for my wife in the garage.
 

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Discussion Starter · #3 ·
Finally, time to get our hands dirty! A couple friends came over and we made short work of C-Rex. We pulled everything down to the engine in one day. In fact, we almost got the engine out too but had hangups separating the engine from the transmission. I wanted to try to keep the transmission in there if I could help it.



I’m not gonna miss you, you underpowered, least-powerful engine to ever grace a beautiful CRX. Nor will I miss your blown valve cover gasket and leaky radiator that I covered with aluminum foil.



Thanks, sis, for filling the gas tank up fully right before the engine died! Haha. At first I thought I was going to have to disconnect the fuel line and use the fuel pump to empty the tank. Luckily, my (all?) gastank had a drain plug that did the trick. I was worried about the flow being so great that I wouldn’t be able to put the plug bolt back in and would have explosive gas spilling all over my garage. But I quickly learned that it drains very slowly if I just put the filler cap back on. So if you’re doing a conversion yourself, don’t worry about that part. We ended up filling two of these storage bins worth of gas, which I happily put in Lexi, my wife’s car. :)



Here I cleanly watch and take pictures from afar as my friends remove exhaust parts. I hate working on exhaust parts. Thankfully I have an awesome impact air wrench that made short work of every bolt it ever met. And awesome friends that wanted to learn about cars. Lesson one, get under there and remove those exhaust parts! It is the most fun part of the whole conversion! ;)



Now the real fun begins – engine removal! My wife joined us for this part, in addition to being a faithful supporter of the EV, she brings a level of enthusiasm that is refreshing for people like me who already know how to rip out the engine. Here’s us donning our favorite headlamps (I love those things), and our friend Mark who stubbornly refused. At least Mark knows how to tie knots. :)



We got the engine all tied up and lifted with the hoist, but alas, it wasn’t to be that day. There wasn’t enough room in the engine bay for the engine and transmission to separate and come clear. We came back another day, refreshed, and me having a good idea from my CRX forum. I piled firewood under the transmission, popped the CV shafts, and we let the transmission fall (onto the firewood which catches it) out below the car, thus freeing the engine to come out the top.



Freedom!!! We then put the transmission back in the car and towed it to our detail guy who power washed and steam cleaned the whole engine bay. You could eat off that surface! This was well worth the twenty bucks he charged me, since I saved hours and hours of the messiest job on earth, fifty million rolls of shop towel, and probably gallons of Simple Green. I mean, just look at it:



Time to go relax and have a cold one. I thought about selling some of the parts to recoup some costs, but in the end I'm so impatient and didn't think it was worth my time dealing with Craigslist deadbeats, so I ended up posting it all for free online. It was all gone the same night.
 

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Discussion Starter · #7 ·
Thanks, guys, for all the kind words. :)

I plan to put in a WarP9 and 45 130Ah CALBs in there, with a Zilla-1K. It should be much faster than the original car, which was the DX, but it should be much faster than even an Si (sports version).

The car will look much better when it gets its new paint job this spring. I've got a new hood, new fenders, front lip, and am going to do a couple simple aero mods to it.

New update to come soon, am writing it up...
 

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Discussion Starter · #8 ·
The next weekend I took a short interlude from the EV, but worked on something related. I had always planned to do some welding for the conversion. So I wanted to practice my welds before working on anything critical, so I built a cart to hold my welder. Yes, those are perfectly working (cheapie china) socket wrenches that hang the cables. Figured that gave my cart a little personality. :cool:

Next update to come: mating the motor to the transmission!

 

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Discussion Starter · #9 ·


The next step was to mate my new WarP9 with my existing transmission. I decided to keep the transmission to optimize both range and acceleration, as well as stock OEM feel. I also replaced the clutch at this point, since it’s all open and apart. I went with a Stage-2 Organic clutch plate. From my research, an OEM or even Stage 1 clutch would probably be unable to handle the torque I aim to throw at it. And a Stage 3 (or Hockey Puck) clutch would be too uncomfortable/annoying to drive, due to the stronger springs. That went against my goal to keep it feeling like a daily driver, so I went with Stage 2. Since an EV needs no “friction feathering” when starting from a stop and thus there is only wear in between shifting gears, I fully expect this new clutch to long outlast the rest of the vehicle. I also got the lightest chromoly flywheel I could find – an 8 pounder made by Fidanza (the stock one weighed in at 20lbs). This is actually a pretty big deal. It should lower my rotational mass quite a bit, helping with range and acceleration. And since I don’t need to balance out any vibrations like in an ICE car, I can go with the lightest weight possible.

To mate the two, I went with an off-the-shelf adapter plate and hub coupler made by Randy at CanEV. My friend has a CNC mill and so I entertained the thought of building it myself, but in the end, time is money and I only have so many hours a week to work on the project. Premade solutions are my friend. I estimate I would’ve spent probably 40 hours measuring, drawing in CAD, cutting in wood, testing, recutting in aluminum, etc. That’s 40 hours I’d rather be driving my car. All in all, the adapter is awesome and was well worth the price tag. There is a good reason Randy’s cost the most – you get what you pay for. Everything I needed, bolts, shaft key, Loctite, etc., was included in the package. Additionally, Honda Civics/CRXs have quite a large “magic number” that would typically mean a very thick and heavy spacer in all the other adapters I considered. The one from CanEV is cast and thus any shape they want. Full disclosure: I actually lost two months on the project trying to get an adapter from another source for cheaper, but was unhappy with the adaptor that evolved out of that large magic number and wasn’t what I’d agreed to purchase. To their credit, they refunded my money with no hassle and were really upright people, so their names won’t be revealed. I think my case was an isolated case. And so if you have a Honda, just get this adapter.



Here’s the coupler mounted to the electric motor. I used a little lubricant to get the coupler on there; it is such a tightly machined fit. Tap it on with a rubber mallet until it bottoms out against the shaft bottom, then torque the locking allen bolts firmly. Everything at this point, I mean everything, gets a coat of red Loctite to prevent loosening from any vibrations (though there aren’t likely to be many with an electric motor).



Here’s the side view after bolting the adapter plate to the motor. I’ve also already mounted the new flywheel in this picture. See what I mean about the custom casting of the thick spacing between the motor and the adapter face? That would normally be a thick spacer ring of aluminum, adding unneeded weight.



Here I’ve installed the new clutch plate and clutch housing to the assembly. It’s now ready to slip the transmission shaft in, aligned to the clutch plate, and mate the two assemblies. Below is the final powertrain assembly – ready to be mounted! :)

 

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Excellent build thread, subscribing.... good luck with your project!

I hope you didn't forget to change direction of brush advancement on Warp9 since Hondas turn in opposite direction. Also keep that in mind when wiring your motor's field and armature, make sure it spins in proper direction.

That adapter plate and shaft coupler look awesome! Randy certainly knows his stuff.
 

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Yes, really nice adapter plate, looks absolutely original oe, fantastic work :)

Did you consider removing the ring gear teeth from the flywheel, or are they getting utilised for something, tach etc?
 

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Discussion Starter · #12 ·
Yes, really nice adapter plate, looks absolutely original oe, fantastic work :)

Did you consider removing the ring gear teeth from the flywheel, or are they getting utilised for something, tach etc?
No, I'm not using the ring gear, and I did think about removing it. But in the end I decided I was already saving so much weight, it wasn't worth the hassle. I also wasn't sure if that would compromise the weight balancing in any way so I just left it alone.

Thanks Dimitri for double checking, I did reverse the direction of the motor! :D I have yet to apply any power to it yet, just haven't had time, but I'd like to stick a 12V battery on there soon just to see a satisfying FORWARD rotation. ;)
 

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Discussion Starter · #13 ·
Time came to mount the motor and transmission assembly into the car. The original assembly was held by three rubberized mounts on the transmission and only one held the original ICE towards the driver’s side. The goal of course was to reuse the engine mount for the electric motor, including reusing the rubber to isolate the chassis from torque twisting and road vibrations somewhat.



I originally tried to make a custom mount out of angle iron with my newly-practiced welding skills (hence the whole reason, besides keeping my welder off the garage floor, why I made a welding cart the weekend before). As you can see, the final product is quite sturdy. The problem was, I kinda just did it as I went, figuring that when I got to how it would actually mount to the original bracket, it would be obvious. But due to where things lined up, there wasn’t really a good way to fasten my mount to the car. Additionally, the thickness of the angle iron meant I couldn’t get it around the dual output shaft of the motor without cutting off most of the motor shaft. I don’t have any plans for A/C or to run anything off that shaft, but I just didn’t like the idea of getting rid of a perfectly good shaft.



So I decided to stop being stubborn and go with a mount that I’d seen before online, courtesy of the blog Open-Source Civic. It’s actually quite simple and thus a quality mount. I originally didn’t want to use it because I wanted to do some welding, but later realized that is a stupid reason to do the wrong thing. So there’s my own version of the motor mount, for a CRX. Instead of spending hours making an aesthetic curve with a jigsaw, I just cut half of a hexagon off the bottom. Just a few minutes with my grinding wheel. :) This mount still required me to cut some of the output shaft off, but not nearly as much. I cut about an inch off and retained slightly more than an inch. Plenty to mount my RPM sensor. Then a connecting linkage is put in place and several carefully measured drill holes, a coat of primer and hard enamel paint, and plenty of Loctite later… <wa-la> the motor is mounted!



That pump you see mounted to the top of the motor mount is my vacuum pump for the brakes, I'll cover that shortly! :)
 

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Discussion Starter · #14 ·
Next up: heater installation. I decided to go with a ceramic heater mounted in the heating duct instead of using the existing coolant lines. For whatever reason I just think it’s more elegant and simpler to go all electric there, plus electric heat comes fairly instantly instead of having to heat up a reservoir of water first. My original plan was to mount the heating element directly into the heater core, which I pointed out in the picture. Many people did that before and it sorta makes sense. But after getting in there to remove the core, I realized that if I ever had any problems with it, it would be an extreme pain to get to. First of all, getting the dash out required three people, and we cracked the windshield in the process. The windshield’s getting replaced anyway, but that’s just a sign of how inconvenient it is to get to. Not only that but once in there, removing the heater assembly was also a pain. I then realized that there’s no reason it has to be there.

I decided to put it in the heating duct that connects the blower to the heater assembly. This offered lots of advantages. For one (and it's the biggest one), if there is ever a problem, I can get the whole unit out by simply removing the glovebox with three screws instead of hours of messing with trim/wires/tachometer cables/etc. Second, when cool air is wanted, the heating element simply remains off and is virtually no impediment to the air coming from the blower. Third, this way I remove the need for the “heat flap” wire that is controlled through the temperature dial. I simply locked the heat flap so it never shunts air where the heater core used to be, thus removing the cable. This is nice because I am going to use the temperature control dial space for an EV Display (SOC gauge) instead. Lastly, it’s not a lot but I lose the weight of the heater core since I don’t need it.



Here is my heater, ready to be tested. It’s a little Sunbeam ceramic element rated at 1500W. Supposedly enough for a small room, so C-Rex should be comparable after all the thermal losses. Walmart’s the only place I found stocking them – it’s allegedly a seasonal item. I guess that makes sense. :) Now that I got it all stripped down naked, I used my little wall-clock/thermometer to see how hot it would get with some airflow.



Here is as hot as my thermometer measured, 115 degrees Fahrenheit. The next snapshot after this the display just says “HI.” I figured that’s hot enough to only need one in the system.



I mounted the element into the duct complete with its original mounting plastic. I figured that some engineering already went into the material that can hold a high-temperature/high-voltage element safely and that UL had already verified – I didn’t want to take any chances with burning my car/garage down. So I kept the original mounts, even the safety temperature switch it comes with, and screwed into that plastic from the outside of the duct. It’s a very secure setup – that heater ain’t goin nowhere. When mounted in the car and running off 120VAC with the blower motor going, the outside of the duct only reaches slightly warm to the touch after running on full heat for half an hour or so.

I’d describe the heat coming out of the vents as moderate. Feels hot enough it should be able to defrost my windows, but it’s not so hot that I’d probably ever take off my winter jacket inside the car. At this point, I don’t want to go to two elements since one takes a whole 1500W when in use. After I get through the first winter (probably won’t even be in by this winter to test it), we’ll see if it needs upgrading.

However, the heat output did have an effect on my temperature control decision. Being an electrical engineer, I thought it’d be fun to design a simple feedback-controlled thermostat. So I did that on paper and was satisfied it was simple and would work reliably. Then I got to actually feeling the heat coming out of the vents and now I think a thermostat is overkill. I couldn’t picture needing to ever adjust the heat much lower than “fully on,” so I decided in the interest of simplicity and time, I will just make my heat fully on or off, and use the blower fan control to lessen it if I want less heat. This will be a change from the OEM feel of the car, but I think it’s a simple enough one. And anyone borrowing the car in the winter will likely not be fiddling with the heater controls since they will want heat as well.

On the bright side, my Zilla is liquid-cooled and I will be using my thermostat control circuit that I designed for that instead. With the circuit I can easily change a few elements out and adjust a desired trip point where the fans for the heatsink come on when it gets hot enough. When I install that system and build the circuit, I’ll post my schematic here so others can use it if they want.

One last benefit of not having a variable temperature (just on/off) for my heat is it frees up that space where the knob is for my SOC gauge. This is key because I wanted the gauge to be mounted somewhere where it could be read easily and not have to take my eyes off the road for too long. There’s no room in the dash for the SOC gauge, though I will be using its output to drive my original Fuel gauge so I can easily estimate remaining range. This will be one deviation from OEM, which had a heater control knob there, but I think the above-listed advantages makes that worth it.
 

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I mounted the element into the duct complete with its original mounting plastic. I figured that some engineering already went into the material that can hold a high-temperature/high-voltage element safely and that UL had already verified – I didn’t want to take any chances with burning my car/garage down. So I kept the original mounts, even the safety temperature switch it comes with, [snip]
Make sure you rewire that safety switch so its contacts control the heater element relay, not directly switch out the element as they did originally. The air gap on those thermal switches are not nearly large enough to switch 100 or more volts DC, they are strictly AC rated.
 

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Discussion Starter · #16 ·
Make sure you rewire that safety switch so its contacts control the heater element relay, not directly switch out the element as they did originally. The air gap on those thermal switches are not nearly large enough to switch 100 or more volts DC, they are strictly AC rated.
Good catch! I'll make sure that gets fixed, thanks.
 

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Discussion Starter · #20 ·
Speaking of batteries, anyone have any thoughts on the AUX 12V battery?

I've decided to use a small 12V battery in case of DC/DC failure. So it only needs power really for a short time if the DC/DC dies or big enough to handle headlight/vacuum pump surges.

My current plan is to get an Odyssey PC680 lead-acid battery. It's 221Wh, which should be plenty, and is fairly light (15lbs), but a little pricey at $135 about. It's a deep-cycle, no maintenance battery. Comparable weight built out of TS 40Ah cells would cost twice as much and about twice the capacity.

I've heard now a few people mention lawn tractor batteries, or maybe motorcycle batteries (thought those were 6V though).

Just wondering what others have concluded...
 
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