RWD Tesla Powered CRX

[Qckslvrslash]

Hello. My name is Martin I am located on Vancouver Island and 9 months into my first EV conversion. I have posted this elsewhere as well, but as many people only visit certain sites I thought I would post a more condensed version of my build here for people to see, comment on and perhaps even learn something from my struggles.

Summary

Donor
1990 Honda CRX Si - Celestial blue

Car was DOA. Distributor and Main relay were caput. Fixed to allow me to drive the car prior to its sacrifice to the conversion gods/

Drive Unit
Tesla Model S Small Rear Drive
-Custom Mounted in Rear of car using CRV trailing arms to convert to RWD

Battery
-12 - LG Chem "Pacifica" Modules 2.6KWh
-Goal is to fit into 2 battery boxes. Secondary in under vehicle box where gas tank used to live

BMS
-New Thunderstruck 16 cell BMS

ECU
Motec M150 and Motec PDM15
-The entire wiring of the car is being replaced. I will be hand building an entire harness as the original CRX has cracked sheathing and many shorts throughout.

Charging
-Ovartech 6.6kw Charger w/1.5kw DC/DC converter (Same one as resold by stealth EV)
-Chademo

Misc Components/Upgrades
- Model 3 A/C compressor
- Electric Power Steering
- Bosch Ibooster
- Power Windows
- Power Mirrors
- Heated Seats
- Aux. Electric Heater

Overall Goal
When I bought the car an EV conversion wasn't the first idea I had for it. However the Kona EV my girlfriend bought was enough to convince me to try something unique. My first and largest goal to the entire build was seamless integration. I have long been inspired by builds like Bad Obsession's Project Binky and their overall philosophy of going overboard, just for the sake of it. Often what has steered me away from conversions in the past is most cargo space seems to go to the batteries, I wanted to avoid this even if it meant more work/complications.

Ultimately Outside of a few giveaways such as lack of shifter, exhaust, or looking under the hood I didn't want to anybody to tell this wasn't a clean example of a CRX when complete

[mdrobnak]

Welcome fellow Motec coder.

This sounds like its going to be quite a fun ride when done. Definitely interested in the iBooster and AC compressor fun, as I will need to tackle that on my BMW 330 conversion.

I'm looking forward to seeing your progress, good luck!

-Matt

[bexander]

Welcome!
I really like the CRX and what you are doing to it!
Where can I find some more pictures and info on the build?

[Qckslvrslash]

I will be catching up with the project here but I have posted it on Hondatech and diy electric. Or every day or so I will compile a more concise post here

[Qckslvrslash]

I feel the best way to concisely catch the project up will be focus each post on a specific section of my build.

Assess what I have and my Plan

With the car home I actually started by fixing the motor it had. I wanted to be able to drive it while I decided on what I would be building. But idle hands and all that it didn't sit long before I started stripping back the layers.

Originally I had thought I would find a wrecked Leaf or Bolt and transplant the entirety over to the CRX. But pretty quickly the idea shifted to a RWD conversion being more unique. Some folded cardboard later I had a Small Drive Unit Mocked up to see if it would even fit.

Happy to say a tesla unit would just squeeze between the main lower control arm pickup points. I scoured car-part.com for wrecked teslas and called yards all over North America looking for a reasonable price on a drive unit and got to work prepping the car.

Trailing arms are modified AWD CRV ones commonly used in AWD swaps. The whole interior would be coming out so I had a blank canvas. Plus my binky inspiration demanded it.

The motor stayed in longer than I would have liked but without a cherry picker it would be one of the last bits to go. That said getting rid of it and the fuel tank felt amazing.

My batteries were one of the first things to arrive. I committed pretty early to the LG "Pacifica" modules and got to some initial fitting pretty early on confirming my suspicions that ever millimeter would matter. So the stock front subframe got replaced

Ultimately this is the setup for the front battery pack. 8 Modules. the other 4 will live in the middle of the car. More to come on that in a future post.

[Qckslvrslash]

Mounting the Motor

The motor arrived on the pallet with a number of extra goodies. The plus side to calling around to lots of different yards meant in the end I found one that wasn't interested and nickle and diming every piece. They basically asked what I would like and they tossed it all in. Some bonuses were, 18ft shielded 2/0 cabling, most of the rear coolant hosing, wiring harness for the whole car's rear. Sadly much of this was cut but it gave me raw materials I'd otherwise had to have paid for.

This was going to prove to be one of the most difficult parts of this build for a number of reasons.
1. While I had measured the clearance between the control arm mounts I was not sure the drive unit would truly fit.
2. If it did clear between suspension mounts the rear crossmember would still have to be cut out.

For this reason before I had bought the motor I had a backup plan. Mounting it inverted. To do this one has to remove the internal oil pump and go with an external electric. Weld shut the vent and make a new one on the bottom and machine a new oil return from the motor side of the drive unit but it can be done. EVRomania did this in their hill climb race Golf.

This would also be the only part of fabrication I wouldn't do myself. While I can weld my garage and lack of lift meant it was far better to leave to professional fabricators. There were some lessons learned in doing this and doing it again would likely take far less time but when you have to work out every single step for the first time it is never fast.

Day 1 - Measure

Little happened the first day in the shop. It was mostly a lot of measuring to make sure things would clear and ordering materials.

Day 2 - Goodbye spare tire
A cross brace was tacked in to add structure and the spare tire well an most of the stock crossmember were cut away

Day 3 - Control mount plates
To add back some strength that was taken away plates were made and welded to the stock control arm mounts.

As we waited for the metal to arrive the hole and positioning were refined.

Day 4 - Materials at last
With the bulk of the metal order showing up finally work could really get underway. The main structure was 2inch box. It was welded to the top side of the unibody rails. In retrospect there was likely just enough space to fit them in line with which may have better suited the goal of making it look 100 percent stock but the lost trunk depth is nearly imperceptible.

Things moved a bit slower over the next few days as other projects in the shop demanded immediate attention but the work continued slowly. Picking up the rear mount was the first solid connection made.

This is also where some time was lost. Originally the side mount was going to need an adapter bracket. With the mounting holes being on different planes with was not straight forward.

However over the next few days as other bits of the structure got worked out a different solution became an obvious choice.

Front and rear mounts complete. Also visible is the triangulation structure on top. To say we added strength would be an understatement.

[Qckslvrslash]

Motor Mounting Part 2

What became clear and entirely by luck was that the stock tesla side mount fit nearly perfectly into the driver side rear lower control arm mount. To make this work the mount would have to be remade just a hair wider and would mean none of the stock mount was in tact. This is exactly why I did not do this part. Too much original structure removed. Pay professionals!

With all three stock tesla mounts accounted for finish welding was last and the main structure was done.

The last step was the addition of a lower cross bar to help add in more rigidity.

And Googly Eyes. You must always give your drive unit personality!

I commend the shop on their work and importantly their ability to keep my own goals with the build in sight. It would be easy to make something that doesn't blend in but the whole time I had left them with rear interior trim so that things would go back together as seamless as possible

You can see how the CRX's lockable cubby really hides the extra height and results in a flat rear cargo area. I had to do some notching on the side panels but the rear fit in with ease and while I still had to add a new skin in myself I couldn't help but put the rest of the trunk trim in.

The lost 1-2 inches of depth are not noticeable in the least since the CRX had such a large trunk to begin with and I couldn't have been happier that it all fit so seamless.

It also meant that any outside help I was going to use on this build was done. The rest was down to me to make it all work.

[Qckslvrslash]

Welcome fellow Motec coder.

This sounds like its going to be quite a fun ride when done. Definitely interested in the iBooster and AC compressor fun, as I will need to tackle that on my BMW 330 conversion.

I'm looking forward to seeing your progress, good luck!

-Matt

Since you are interested in the Ibooster I will cover it next.

Brakes - 2018 CRV Bosch Ibooster Gen. 1

One of the biggest things I have learned over the course of this build it to avoid the Tesla tax everywhere one can. A quick check of ebay shows most "Tesla" units selling for between $400-1000 which is an insane markup especially when I got the exact same thing from a 2018 CRV for 100 Canadian plus shipping. The only difference between the CRV and model S booster is the reservoir and funnily enough the bosch part even in the honda has tsla as part of the coding. On the CRV it is remotely mounted as the booster is buried deep in the engine bay.

Now it was 100 percent luck that the iBooster fit so cleanly, but it also makes sense for parts commonality that the bolt patterns would remain the same. There were only two things I needed to change. First I had to take about 0.5m off the main hole through the firewall and second I had to fit a square peg in a round whole. The CRX firewall was contoured to fit the back of the vacuum booster. To do this I sacrificed the stock booster and welded the bosch mounting plate to create a seal on the firewall.

This let me use the stock gasket and served to space the booster away a bit. The final
fit was great and the fact that the bosch master cylinder bolts to the booster means I could flip the unit whichever way I pleased so as to fit

These units are used in a lot of vehicles these days and I think this largely has to do with a couple things. Not relying on vacuum means that even when an engine is making boost the computer will have full braking available for emergency braking. This is actually a common issue in rally cars where left foot braking is used and why basically the first modification to making a rally car is tossing the vacuum assist and going full manual.

For their wiring. One of the hardest parts to the ibooster was its plugs. Mine didn't ship with pigtails I managed to find the bosch part numbers but the plugs are near impossible to find in low quantities. I was quite pleased when I did find one enthusiast in the Netherlands selling a number of these bits. https://www.evcreate.nl/shop/brakes-whe ... ector-kit/


I originally found the info in a Chrysler Pacifica Manual.

When you remove the canbus communications which aren't vital to the unit functioning you are left with this.

My assumption is most the CAN protocol has to do with adaptive cruise and emergency braking none of which is needed and would be a safety nightmare to try and get correct. All said I do wish bosch had used a cheaper connector as it cost me as much as the booster in the end but I suspect it was all they had in house that had the mixed pin sizes they needed to power the thing up.

[Qckslvrslash]

HV Circuitry

This is a place I welcome criticism or advice. I have read just about everything I can and there seem to be varying opinions on best practices for HV structure. I have tried my best to create a reasonable setup based on these but I am still fallible.

For Current monitoring I am using a Sendyne SFP 200 which are capable of 600A continuous at 1000V. Not shown is the Sendyne Sim100 ground fault isolation monitor. Needless to say I am building this as safe as possible and sign of trouble things will shutdown.

The batteries are split into two pack for weight distribution and concealment. 8 in the engine bay with 4 where the gas tank used to live.

All main HV wiring will be 2/0 shielded cable fed through Gigavac GV200-MA contactors. The positive contactor precharge will be controlled by a Zeva smart precharge unit.

Right now my ancillaries are not isolated by their own contactor but instead a main disconnect switch. This will let me shut off power to everything when the car is sitting longer but also enables some of the wakeup functions I am programming. Things such as DCDC on low 12+ voltage etc.

[Bratitude]

Awesome, and your a islander! you me and arlo should go for a cruise!


are you planing on having contractors to separate each battery box?

very interesting the crv ibooster you picked up has Tesla markings. Evcreate is Lars, he’s active on here.

interested to see if the can IDs differ from the official Tesla ibooster. Have you gotten the ibooster functioning ?

[Qckslvrslash]

Awesome, and your a islander! you me and arlo should go for a cruise!


are you planing on having contractors to separate each battery box?

very interesting the crv ibooster you picked up has Tesla markings. Evcreate is Lars, he’s active on here.

interested to see if the can IDs differ from the official Tesla ibooster. Have you gotten the ibooster functioning ?

It is something I hadn't been intending to do based on some advice from Motec and talking to their EV developer. While I know it is common to separate parallel packs with contactors I intend to leave them permanently paralleled with an emergency disconnect that is normally closed. This would be monitored at all times the car is "live" for excess cross current

While my understanding is a little more crude it amounted to with EV batteries they are designed to handle such high loads imbalances aren't the same level of issue and the packs will naturally remain in balance. This will be a similar setup to their development mule which used two Volt battery packs in parallel.

[Bratitude]

it’s not out of concern for cell balance, it’s a isolation safety thing. all depends. For example a battery box up front and one in the rear, at least one connection per box should be isolated in its neutral state. in the event of a crash, you want to minimize the amount of potential live connections.

Sasha and his lotus had his volt packs all stuff together. Thus there’s no live leads draped across the car, no need for pack contactor separation in his respect

[Qckslvrslash]

it’s not out of concern for cell balance, it’s a isolation safety thing. all depends. For example a battery box up front and one in the rear, at least one connection per box should be isolated in its neutral state. in the event of a crash, you want to minimize the amount of potential live connections.

Sasha and his lotus had his volt packs all stuff together. Thus there’s no live leads draped across the car, no need for pack contactor separation in his respect

Most discussion I have seen on the topic always seems to revolve around cell imbalance and cross currents. Hadn't considered vehicle state in a crash. The disconnect would be able open and separate the packs in the event of a crash, or I could program it to easily. The pack on a module basis is 8 up front and 4 in the back. So two modules from the "rear pack" actually live in the engine bay with the main one.

I actually got lucky and kinda seem to have slid in as Sasha's guinea pig for controlling a Small Drive unit. He is also who I have been chatting with when I hit a wall or find no solid information online on a subject or worse conflicting info.

[Qckslvrslash]

Awesome, and your a islander! you me and arlo should go for a cruise!


are you planing on having contractors to separate each battery box?

very interesting the crv ibooster you picked up has Tesla markings. Evcreate is Lars, he’s active on here.

interested to see if the can IDs differ from the official Tesla ibooster. Have you gotten the ibooster functioning ?

Also regarding the ibooster the numbers are identical to tesla units having compared them online. The only difference is the master cylinder bolted to the end which is a different part. I suspect the CAN protocol would be something bosch set up though I could see it being manufacturer configurable. I briefly bench tested it with some alligators but haven't powered it up or tested with my brakes as I need to put different fittings on and reflare the brake lines to bolt to the master cylinder.

[Qckslvrslash]

Two pretty cool things turned up in the mail today.

Sendyne Sfp200 and Sim100 responsible for my current monitoring as well as detecting any hv leakage to chasis.

[Dusty4]

hi qckslvrslash,
nice project! I look forward to seeing it progress, may I ask where you got the sim100? I have reached out to sendyne but had no reply..

[Qckslvrslash]

hi qckslvrslash,
nice project! I look forward to seeing it progress, may I ask where you got the sim100? I have reached out to sendyne but had no reply..

Yeah I was struggling to get them myself. I had Mountain Pass Performance/Motec Canada order them for me.

Of note they don't come with any connectors so you have to order them seperately. I really think sendyne works exclusively with larger parties.

[Isaac96]

Yeah I was struggling to get them myself. I had Mountain Pass Performance/Motec Canada order them for me.

Of note they don't come with any connectors so you have to order them seperately. I really think sendyne works exclusively with larger parties.

A year ago or so (July) was looking at isolation monitors. I emailed 'sensing at sendyne dot com' and they replied within the day, quoted $300 for the SIM100MOD. Maybe ask them; times might have changed.

-Isaac

[Dusty4]

Yeah I was struggling to get them myself. I had Mountain Pass Performance/Motec Canada order them for me.

Of note they don't come with any connectors so you have to order them seperately. I really think sendyne works exclusively with larger parties.

A year ago or so (July) was looking at isolation monitors. I emailed 'sensing at sendyne dot com' and they replied within the day, quoted $300 for the SIM100MOD. Maybe ask them; times might have changed.

-Isaac

Hi Isaac,
Yeah that's who I emailed.. times must have changed..
I'll give mountain pass performance a go. thanks Qckslvrslash

[Qckslvrslash]

Yeah I was struggling to get them myself. I had Mountain Pass Performance/Motec Canada order them for me.

Of note they don't come with any connectors so you have to order them seperately. I really think sendyne works exclusively with larger parties.

A year ago or so (July) was looking at isolation monitors. I emailed 'sensing at sendyne dot com' and they replied within the day, quoted $300 for the SIM100MOD. Maybe ask them; times might have changed.

-Isaac

Yeah I was struggling to get them myself. I had Mountain Pass Performance/Motec Canada order them for me.

Of note they don't come with any connectors so you have to order them seperately. I really think sendyne works exclusively with larger parties.

A year ago or so (July) was looking at isolation monitors. I emailed 'sensing at sendyne dot com' and they replied within the day, quoted $300 for the SIM100MOD. Maybe ask them; times might have changed.

-Isaac

Hi Isaac,
Yeah that's who I emailed.. times must have changed..
I'll give mountain pass performance a go. thanks Qckslvrslash

Price hasn't changed. I paid 299USD for mine. I suspect it has more to do with them not wanting to deal with a massive influx of independent people calling buying single boards and then follow up questions on how they then work. By having them bought through third party's they then have a knowledgeable intermediary to deal with basic questions.

[Qckslvrslash]

Steering

This is honestly probably one of the more complex things I undertook. On the surface adding an electric steering motor inline isn't too large a task. What made it difficult was the spacing. This gave me the biggest appreciation for project binky and the insanity of that build.

Objectives
-Maintain stock wheel and column switches
-Maintain tilt
-No differences visible with dash plate on
-maintain or improve collapsing length, should I get in an accident my face will thank mme

The donor was a 2015 Nissan Versa EPS Column. While I intend to decode the CAN signals this unit works in a default setting without them and importantly has its control module in a seperate box giving me some flexibility.

A look at the stock rack shows the available space

A complicating factor was differing spline and diameter on the wheel end of the shaft. After some careful measurement I cut off the end of the stock CRX column and spliced it onto the cut end of the nissan rack.

This accomplished two main things meant I could put the CRX wheel and column switches on the end of the Nissan rack while maintaining the entire Nissan plunge length. The tab the column switches mount to also let me correctly clock the tilt mechanism and weld it to the outer Nissan shaft.

The first test fit was promising. And with nothing yet supporting the motor and inner shaft I could now clock the motor so it best fit

the last thing was to make a mount connecting the motor and the stock rear tilt pivot. For this I used the bracket that held on the controller and welded it to the pivot. And weld the CRX spline to the end of the intermediary shaft.

All told I am quite happy with the final fit.

The control box got mounted up to where the stock fusebox originally lived. Everything happily hidden out of site. Some time soon I am going to find a Versa to plug into and Can sniff so I can make some custom assist curves. My keypad will also have an override state both for max assist and no assist

[Qckslvrslash]

Batteries and Battery Boxes

This is really the largest outstanding part of the build. With much requiring the battery location to be finalized before I can complete wiring everything together. Today the blanks for my plates arrived after several months of second guessing myself so I feel I can cover this with some certainty now.

The Basic design will see 8 modules under the hood with 4 living mid car where the gas tank previously lived. Several attempts with cardboard led me to this being the best design for the rear. The batteries will live in this box inverted with the rear cooling plate atop them.

The notched step was necessary to clear different bits of the rear body and the new motor mount. You can see in the images below how it just steps around the toe arm mount. Normally I might worry about access to the bold but the ktuned adjustable links mean I no longer need access to the original factory cammed bolt and even then could likely just squeeze a wrench in if need be. I needed the step so that the main leads and bms plugs had clearance.

Without plates

With Plates

To say I am pleased with the fit and was relieved is an understatement.
1. I spent a lot of time accurately cutting the cardboard so I knew what I had made in cad would work
2. Ordering the plates was still a large expenditure and one it could be hard to fix should I have gotten things wrong. Likely would have meant new plates

What makes them special is they are t6061 precision ground to within .005" on thickness and within .015" in flatness the same standards as MIC6 plate. Due to the split plate design and my lack of access to things like vacuum brazing the plates need to fit together very tightly so I won't have leaks. Between them will sit a homemade gasket. The cooling won't be at high pressure but I still need them to be water tight.

The front box was more simple The main clearance item there was the front track rod subframe. I replaced it with an aftermarket unit to buy more space but it will still be tight.

The front box will have two cooling plates each with 4 batteries sandwiching it.

The front box is also going to house my contacters, charger etc. It will be tight and probably a pain to work on but should be a super clean look in the end

[Qckslvrslash]

To relocate the battery from its stock location I threw together a new battery box. This served as some practice prior to making the larger main battery boxes. It is going to mount between the firewall and traction battery.

[Qckslvrslash]

Short update

Most of my HV wiring supplies showed up this week. Step one is to start figuring out how to fit everything in the space available. A couple items on backorder but it is a start.

In an effort to get all electrical items into location so I can build my harness I picked up a Sony double din unit w/ android and apple auto. This meant cutting apart the single din CRX console. Japan had double din units but they cost an arm and a leg. This was 20 bucks give or take.

I am pretty pleased with the result. I need to get some glazing putty to fill the pinholes. Then a couple coats of paint.

[Qckslvrslash]

I'm sure I mispoke about something. So don't roast me too hard