# 90 CRX Si - RWD EV Conversion



## Qckslvrslash (Oct 29, 2019)

First thing I tackled was figuring out what was wrong with the sunroof. 

It looked like nobody every service it or lubed the cable drive









Everything was seized solid 











Judicious application of WD 40 and heat eventually broke the cable drive free. After which it became a repetitive process of lube up, run it back and forth, clean out and relube. 










I then gave everything else a good clean. Sandblasted and repainted the tray and called it a job well done.

I had yet to commit to what kind of build I wanted this to be. So I started in on some CAD and broke out the cardboard to see just what might fit


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## Qckslvrslash (Oct 29, 2019)

It looked like I had just enough room to fit a Tesla small rear drive unit into the back end of the CRX









Which was enough for me to go full send and start tearing everything gas related from the car










It was pretty liberating to remove things with zero care of ever having to worry about fitting them back in. Usually replaces a fuel tank is a pain but a knife and side cutters made short work of all the lines. Though as I got to the interior wiring I was decidedly more patient and careful removed the harness hoping it could be saved. Bit by bit I stripped the layers back. 










Until she was nearly a bare shell


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## Qckslvrslash (Oct 29, 2019)

With the car stripped down the motor was the final victim of the purge.









The front traction bar subframe was next to go as I needed as much room up front as possible and an aftermarket performance one saved a good deal of space over the stock one. 










Battery jenga followed suit as I planned out how to fit the 12 LG modules in. I ultimately decided laid on their side would work best. The other 4 modules are going in the middle of the car where the gas tank used to live to better distribute weight and leave room up front for a contactor box and the charger.


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## brian_ (Feb 7, 2017)

Interesting. 

Are you not planning for thermal management of the battery modules (chill plates)? There doesn't seem to be enough room allowed for that... or for a battery box. Or a radiator.

At the other end, what did you settle on for suspension... the AWD version of the CRC/Civic suspension?


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## Qckslvrslash (Oct 29, 2019)

brian_ said:


> Interesting.
> 
> Are you not planning for thermal management of the battery modules (chill plates)? There doesn't seem to be enough room allowed for that... or for a battery box. Or a radiator.
> 
> At the other end, what did you settle on for suspension... the AWD version of the CRC/Civic suspension?


Funny you should ask. I 100 percent am planning to cool the modules. I haven't finalized their design yet as until the motor was mounted I did not know 100 percent where the batteries would sit. 

This was an early model of one design for a cooling plate. As you can see at this point batteries were going in sets of 3.









For suspension modified CRV trailing arms were used. To fit a Civic/CRX they need to be shortened a bit








The were accompanied by some k-tuned upper and toe mounts to give me some adjustment options. 

When all is said and done I will be getting some coilovers with custom spring rates to deal with the slight increase in curb weight ~400lbs total


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## Qckslvrslash (Oct 29, 2019)

After the cardboard measuring and some follow up with an actual tape measure and at least one backup plan should the motor not fit as intended I found this beauty at a wrecker. 










Tesla Small Rear drive unit. The plan was to mount it as tesla does behind the axle it drive with a backup of running it inverted and thus forward if I couldn't make the adequate clearance. 

Several months went by as I waited for a spot on a lift at a local shop as cutting out the floor of my car and the main rear cross support was not something I was going to take on alone. The day arrived in September and after some measuring again the hole was cut and the future of the CRX sealed. 


















The hole grew over time as new frame work came into shape










Bit by bit the motor mount came to shape. 









The motor side mount is what changed the most as it was realized placement meant we lucked into the side mount fitting into the lower control arm mount









With that done the motor was mounted. 
















A cross bar was made to give the lower control arms some extra support.


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## brian_ (Feb 7, 2017)

Qckslvrslash said:


> I 100 percent am planning to cool the modules.
> ...
> 
> This was an early model of one design for a cooling plate. As you can see at this point batteries were going in sets of 3.
> View attachment 120917


Good to hear. 

But I'm not sure about the coolant circulation pattern. Normally inlet and outlet manifolds are used, with multiple loops between them, so that each module gets similar cooling. In this scheme all modules see the same coolant flow rate, but with an increasing temperature from the module on one end to the module on the other; even the cells within a module are in a similar sequence.

Have you seen the cooling flow in the Chrysler Pacifica Hybrid cooling plates? I haven't, but they have the modules in sets of three like that, with a cooling plate on the bottom, and whatever they do might be a good example to consider.


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## brian_ (Feb 7, 2017)

I'm glad that the suspension approach worked out, and the available room versus the drive unit is very fortunate. The structure looks good, and certainly shows both that this sort of conversion can work and that it is far from the trivial exercise that some people tend to suggest it will be.


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## Qckslvrslash (Oct 29, 2019)

brian_ said:


> Good to hear.
> 
> But I'm not sure about the coolant circulation pattern. Normally inlet and outlet manifolds are used, with multiple loops between them, so that each module gets similar cooling. In this scheme all modules see the same coolant flow rate, but with an increasing temperature from the module on one end to the module on the other; even the cells within a module are in a similar sequence.
> 
> Have you seen the cooling flow in the Chrysler Pacifica Hybrid cooling plates? I haven't, but they have the modules in sets of three like that, with a cooling plate on the bottom, and whatever they do might be a good example to consider.


I have done some research into stock setups. Yes there are compromises in my setup but several modules across an increasing temperature gradient is pretty common. The stock pacifica setup has each set of 3 on a single cooling plate with an inlet/outlet at the front.










It is routed much like this Chevy bolt plate. There is some mitigation to gradient with the doubled up flow but you will never completely get around it. Worth noting that due to the smaller channels my cooling plates will be in parallel to one another which will counter some of this as well. Unfortunately there are limits to what a guy can do even a routed channel is a significant step back compared to microfin or other cooler styles.

This is a link to a pdf on a paper comparing both different coolant channel distributions and flow rates.


https://www.mdpi.com/2313-0105/6/1/17/pdf


It serves to highlight the effect on homogeneity of adding more channels but also how increased flow greatly helps. Ultimately I have to balance cost of production against results. To me imperfect cooling still far exceeds zero cooling and since people quite frequently run these batteries in setups with zero cooling so I am doing better than most. If there were a market for cooling plates for these modules I may spend the effort to design a better one and produce and sell it. But the modules can't be bought anywhere currently which means production runs aren't an option. 

As far as the engine mounting if I stayed FWD and was happy loosing all my cargo to batteries it would be a lot more simple. As it stands I spent most of yesterday trimming up the interior to fit around the new bracing/mount. I will only loose 2 inches of cargo depth.









Which I suspect nobody will even notice when all finished and carpeted.























It was the goal of the whole build. For everything to look and feel stock until the vehicle moves.


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## Qckslvrslash (Oct 29, 2019)

My last few posts brought everything up to date as far as the motor mounting went. However it was far from the only parts of this project. One of my earlier decisions once I went electric was to add in electric power steering and electric brakes as I had no desire to listen to a vacuum pump.









The Bosch brake booster is out of a 2018 CR-V it is near identical to the tesla ones with the major difference being the remote resevoir, and the fact it cost me 100 bucks on ebay vs the 700 people ask for a Tesla one pretending it is special. One of the funnier bits being that Bosch's internal naming has TSLA as part of the part number. 

Fitting it was relatively easy. Removed the stock Honda vaccum booster and insert the Bosch one. It wasn't quite that simple as the fit was a little tight but a quick sand of the main opening meant it fit right up. The shape of the firewall and iBooster weren't quite the same either so I sacrificed the stock booster and used its backside to get a nice tight seal on the firewall


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## Qckslvrslash (Oct 29, 2019)

brian_ said:


> Good to hear.
> 
> But I'm not sure about the coolant circulation pattern. Normally inlet and outlet manifolds are used, with multiple loops between them, so that each module gets similar cooling. In this scheme all modules see the same coolant flow rate, but with an increasing temperature from the module on one end to the module on the other; even the cells within a module are in a similar sequence.
> 
> Have you seen the cooling flow in the Chrysler Pacifica Hybrid cooling plates? I haven't, but they have the modules in sets of three like that, with a cooling plate on the bottom, and whatever they do might be a good example to consider.


Update on the cooling plates. I finally got around to modelling them tonight more accurately to the current intended setup

The flow in the battery loop will be split 4 ways. My charger/DC converter, and then each of the 3 cooling plates. Each cooling plate will be sandwiched between 4 modules. 

The flow rate was set at 1/4 for the test with each module putting out 1100W of heat.

















Inlet temp set to a fixed 20 Celsius with outlet temps around 27C

The plate itself has the one main cool spot at the inlet but from the back side you can see the majority is kept around 23C. 

My system for now will not have a chiller thus anything sub ambient will be impossible but given where I live I expect I will be able to fast charge and keep the temps under control. Plus side if things get too warm somewhere in the loop each battery has 2 thermocouples and I will have a control loop to back off charge rates and driver warnings if battery, or drive unit temps ever climb. The drive unit is on its own loop.

Both loops will have a 3 way valve. On the batteries this will control flow to the rad vs a closed loop to keep temps up in cooler weather. On the drive unit the valve will switch flow between the radiator and Heater core. I also have a small PTC as backup heat there should I need it. 

These are the two radiators. Each will have a fan. They are Mishimoto aftermarket replacements for the Auxiliary rads in a 2016 Camaro SS. Based on some back and forth with Sasha from Mountain Pass Performance (did the Tesla Powered Lotus) and Chris from Zero Ev. We expect these to provide adequate cooling for the build.


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## Qckslvrslash (Oct 29, 2019)

A 3 hour drive to a local wrecker provided fruitful today. I have been looking for some time for a Chademo plug on the cheap as I just wasn't willing to front the 750-900 dollars most places are asking for an inlet. 

A leaf's loss is my gain. Scored both of charge plugs from a 14' leaf and the 1.5 meter's or so of associated cable. 









What was also funny is I drove 6 hours total to get plugs that were from a vehicle sold 4 blocks from my house. 

If only installation were as simple as pushing it into the old gas filler. 









That is where the 1772 plug will live. I suspect the chademo will be tucked away under the hood. While popping the hood to fast charge isn't something I necessarily want to do all the time some sacrifices must be made for vanity. Goal of the whole build is to have what looks like a stock CRX and there just aren't many options to hide an outlet that large.


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## remy_martian (Feb 4, 2019)

Nice work. I like your booster mount and choice of the SDU.

What tool did you use for your flow/cooling analysis?


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## Qckslvrslash (Oct 29, 2019)

remy_martian said:


> Nice work. I like your booster mount and choice of the SDU.
> 
> What tool did you use for your flow/cooling analysis?


That was all done in solidworks. I am fortunate to have access to it. Not sure what fusion360 has but it is free


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## zrickety (Dec 4, 2020)

Awesome build, subscribed.


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## Tremelune (Dec 8, 2009)

It looks like you've got the hardest bit out of the way! Now it's just fitting the batteries somewhere...


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## Qckslvrslash (Oct 29, 2019)

Tremelune said:


> It looks like you've got the hardest bit out of the way! Now it's just fitting the batteries somewhere...


Fitting the batteries has been a pain. Mostly because finding a shop to cnc the cooling plates has been a nightmare.


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## wjbitner (Apr 5, 2010)

Qckslvrslash said:


> Fitting the batteries has been a pain. Mostly because finding a shop to cnc the cooling plates has been a nightmare.


Have you tried eMachineshop.com? They take a cad drawing, and give you a bid. They are a bit slow, (maybe the work goes to China??) but they do seem to be able to make a piece from a cad drawing.


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## Qckslvrslash (Oct 29, 2019)

Last week and a bit have been tinkering with heating options. 

There will be two coolant loops one for the batteries, charger/dc/dc and a second for the tesla motor/inverter. 

Each loop will have a valve to control coolant flow. In the batteries the valve will simply cut the loop to bypass the radiator if battery temps are low. The motor loop valve will direct the flow either to the radiator or the stock heat core. Knowing an electric won't produce the same levels of heat as an internal combustion I decided some form of auxiliary heat would be a nice add on. 

I specifically am avoiding 400V PTCs as I don't want to sacrifice range. I'd rather supplement what waste heat the car does produce. 

I have gone through a couple Aux heaters from Euro cars to mess around with.

I started buying a BMW 87 Aux heater unit. 








You can see each of the main lugs. The board is effectively just a bunch of smart switches to turn on the number of elements requested over lin bus. You can solder a ground to pin one of each switch for manual control. See Damien Maguires video for more on this process. My main issue with the BMW unit is it is just too big to fit anywhere. 

So I moved on and grabbed a Phaeton's Aux heater.









You can see this unit is much smaller. 









The center top lug is ground with the 2 outer ones being 12v+

Much like the BMW it has a control board with some smarts on it to control on/off and level









A bridge between the center lug and the ground pin would be needed to turn this unit into a "dumb" one as I couldn't read the IC's part number to work out how to turn it on and off.
While this would be easy enough to do and for its size it puts out a surprising amount of heat. It was too small to really fit well anywhere. It would mean restricting airflow somewhere to force through the heater and CRX fans aren't too powerful to begin with. 

This brought me to my third PTC out of a B5 Passat









It's about 2/3 the size of the bmw one and should fit perfectly (it is still in shipping) The other thing that I like is it is a "dumb" heat no linbus, canbus, kline. In the original setup it has two relays a low and high. each feeding one of the 2 12v rails. 

The nice thing with all these aux heaters is they are very cheap. $20 or less on ebay and you can find them. 

On the point of not wasting battery, these should be a little easier on my system as they are intended to supplement the waste heat I do have vs provide the entirety of my heat. I am rigging up a small switch so that it comes on only when heat is turned to "11" and I will have an override in my ecu based on battery state.


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## brian_ (Feb 7, 2017)

Qckslvrslash said:


> ... That is where the 1772 plug will live. I suspect the chademo will be tucked away under the hood. While popping the hood to fast charge isn't something I necessarily want to do all the time some sacrifices must be made for vanity. Goal of the whole build is to have what looks like a stock CRX and there just aren't many options to hide an outlet that large.


The small glass panels that flank the vertical part of the rear window are probably too small to fit the CHAdeMO inlet, and it would be pain to fabricate the hinged door, but it would be slick!

There's always the classic American fuel filler location: behind a hinged rear license plate. That's way too low to be convenient, of course. 

For any possible second location, the J1772 and CHAdeMo inlets could be reversed putting the larger one (the CHAdeMO, right?) in the more accomodating fuel filler spot.

And it's an inlet, rather than an outlet, but you know that.


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## brian_ (Feb 7, 2017)

Qckslvrslash said:


> ... As far as the engine mounting if I stayed FWD and was happy loosing all my cargo to batteries it would be a lot more simple. As it stands I spent most of yesterday trimming up the interior to fit around the new bracing/mount. I will only loose 2 inches of cargo depth.
> ...
> Which I suspect nobody will even notice when all finished and carpeted.
> ...
> It was the goal of the whole build. For everything to look and feel stock until the vehicle moves.


Very nicely done!


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## brian_ (Feb 7, 2017)

Qckslvrslash said:


> I have done some research into stock setups...


Thanks for the illustration of the Bolt cooling plate - no one seems to show this part of any pack in teardowns.

The new flow pattern looks good.  This is certainly better analyzed than the vast majority of conversions!


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## Qckslvrslash (Oct 29, 2019)

brian_ said:


> The small glass panels that flank the vertical part of the rear window are probably too small to fit the CHAdeMO inlet, and it would be pain to fabricate the hinged door, but it would be slick!
> 
> There's always the classic American fuel filler location: behind a hinged rear license plate. That's way too low to be convenient, of course.
> 
> ...


I may have finally found a shop to actually cnc the cooling plates. Which would be the last major hurdle before I can really fit and assemble everything. 


The chademo plug is bigger that the fuel filler recess. Which wouldn't be too big a problem as I could make new cavity except it also hits interior pieces as the plug is deeper/bulkier that the 1772. 

For similar reasons it isn't practical to try to make it fit into one of the triangle garnishes while dimensionally it would likely fit and be super slick. The backs of crx's are already prone to water ingress which then gets into the light housings. The time and effort just aren't there for me.

















You can see how deep the plug goes behind its mounting point


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## Qckslvrslash (Oct 29, 2019)

Going to try and keep concise a lot of what has been done. If there are questions I will happily answer them but a lot of this stuff has been done by many people and is really just measuring and fitting to your own application. 

First big thing was getting the Electric Power Steering in.









Top is the The top of the Nissan EPS column. I spliced the Honda end on to keep my stalk and switches the same. The amount of measuring and remeasuring here was immense









Happy everything was aligned it got welded together. You can see in this picture the Nissan upper is press fit. I wanted to keep this and as much of the nissan inner shaft as possible. I have about 6 inches of plunge should I get in a crash. WOOT Safety!

Next I adapted the Honda Tilt Mechanism on. Since I had the mount for the plastic shell and stalk I used these to help locate the tilt
















The tilt was only welded to the outer sleeve. Important to maintain the aforementioned plunge. It also meant I could clock the motor in location for best fit. 
















I was quite pleased with the fit. This wouldn't be possible if I was keeping the stock fusebox but since everything is going to pdm I had some nice hidden space under the dash. With the motor aligned I had to make a mount to pick up the back of the motor and the stock tilt hinge. 


















With it in and secure the final piece of the puzzle spent 2 months in mail purgatory. A Nissan Lower shaft. I knew it would fit the motor and it would give material to work with. Secretly I hoped it would just fit. And if Nissan and Honda used the same number of splines on the same sized shaft it would have. Sadly Nissan decided to add 2 splines compared to the Honda. This was pretty easily fixed. Honda lower spline welded on and I had working steering. I have tested the power steering and it works but I don't have the proper connector for the power so it is a little sketch and I only did it on the bench. That said the car is so light right now a pinky finger can turn the wheels. 

















You can also see my fancy Tesla (really a ford focus) throttle pedal bracket. My original one was pretty junk. So I did some binky inspired Cardboard Assisted Design and came up with a better one. Picked up a bunch of holes on the firewall and one stock pedal mount. The small amount of sanding on the top of the pedal and bracket is to clear the actuator on the air distribution box in the center console. I really do appreciate Project Binky a whole lot more going through mounting all of this. Millimeters to spare in so many places.


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## Tremelune (Dec 8, 2009)

I gotta ask...Why bother with Nissan steering?


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## Qckslvrslash (Oct 29, 2019)

Tremelune said:


> I gotta ask...Why bother with Nissan steering?


It was more about adding power steering. I could have hunted down a JDM power steering rack and paid a fortune or have gone the EPS route. Specifically the nissan because it is known to be one that functions without canbus signals. That said I have a couple friends with Versa's, the rack is a 2015 Versa. So I will be able to canbus sniff their cars and get the correct signals to do speed proportionate steering.

I am also going to have overrides on my keypad. Basically cycle through. Auto (Speed Proportionate), One (max all the time), Off

Having power steering to me is more enjoyable than not. Even pre conversion parallel parking wasn't a lot of fun. and the car is getting both slightly heavier but also wider stickier tires. Plus the final reason. Why not?


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## Qckslvrslash (Oct 29, 2019)

My weekend project was to sort out my heating

A bit of background I am running 2 seperate cooling loops in the car. One for the drive unit one for the batteries and charger/dc to dc converter. Each has a 3 way diverter valve. On the drive unit side it directs the coolant to either the radiator or the cabin heater core. On the battery side it bypasses the radiator, this is to allow the batteries to come up to temperature when it is colder. Plan is to potentially add a heater to the bypass loop should I find my temps consistently lower than ideal. 









Living on in the pacific northwest means humidity and window fogging. I also suspect the drive unit waste heat won't be enough to keep me completely comfortable in the car so to supplement the heat I am going with a Auxiliary ptc heater. 


This led to a goldilocks and the three bears. My first BMW heater was too big. The second VW phaeton was too small with the VW jetta one being just right. Funnily in my test setup the tiny phaeton one put out just as much heat as the larger versions it just needed more airflow. 










Sizes for anybody else doing this. This is of the heater area and not including the external body
VW Phaeton 4.75 x 2.75 x 0.75 in
VW Jetta 8 x 5.8 x 0.5 in
BMW E90 10.5 x 6.5 x 0.5 in

Working out where to fit it was the major task. As shown above the stock heater core is staying. Ideally this would sit against said heater core however the honda routing made this impossible. I decided the PTC would live in the join between the A/C module and the main air distribution plenum. So I cut a hole large enough to fit.
















Next I took some careful measurements and cad up a bracket to pick up the stock VW tabs 








I was pretty please to get the tiny lip that helps seal and seat the unit on my first go. I let my printer get to work and wondered if I'd messed up.










Couple places had to get trimmed to fit around the clips that hold the boxes two halves together. On the top there is an internal feature that holds the plastic end so when the ptc is seated it can't move. I also made sure to leave clearance around the metal fins. 

















It all fits like a dream. I do have one other piece printing right now to close in the bottom features and I have to bond the new housing on in place. The distribution plenum will have a couple rivnuts to secure the two pieces together as the stock strap will not fit. Then I will wire it all up on the bench with the blower.


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## Qckslvrslash (Oct 29, 2019)

Another thing I should add re: the ptc heaters. The Jetta one is by far the easiest to ingrate as it is switched by relays and "dumb" the other two have control boards. You have to open them up and solder on wires to the correct pin of the internal switches to have control over them. Damien Macguire has covered this in posts and videos. For me with my PDM it is far simpler to integrate the dumb unit


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## Qckslvrslash (Oct 29, 2019)

The heater is done and I am quite happy with how it is working. With the fan on medium the heater produces a 20F delta over ambient temperature. While it isn't blazing some rough math suggests a 1000W PTC should be able to heat the cabin in 15minutes. With the waste heat from the drive unit I suspect this will be adequate.

This post is about something different though. I have put together my HV Diagram. I welcome criticism or advice on this. There are so many opinions on the "right way" it can be hard to filter good advice from bad. Please disregard pin 13 being doubled. I forgot to fix it


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## Tremelune (Dec 8, 2009)

Nice! Consider cheap heated seats. They take the edge off, and power consumption is negligible.


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## Qckslvrslash (Oct 29, 2019)

Tremelune said:


> Nice! Consider cheap heated seats. They take the edge off, and power consumption is negligible.


Planning to. Just got myself the center armrest from a 96-2000 civic which has 4 switch spots. 2 will be heated seats. Other two will likely be for my windows


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## Qckslvrslash (Oct 29, 2019)

Rear Battery Box - 4 Battery Modules

Working out the design of the rear box has been intensive. I am putting 4 modules in where the gas tank used to live. The main obstacle is the front mount of the drive unit. My decision not to modify any of the mounts means I can slip any rear drive in should something happen to mine. This puts a fairly large protrusion forward into the gas tank area. 

The forward edge (green) has a slope to fit the chairs in their back position. The red line outlines the space between the "frame rails" and the constraints the drive unit imposes.










My eureka moment was flipping the batteries upside down, cooling plate on top. This allows me to hug the batteries with the upper box and flare out near the bottom for the connections.


















And since the motor mount is offset to one side I had room to fit in a tunnel for the coolant line hookup. With a working idea I did what all good builders do, I mocked it up in cardboard. The battery will sit .75in high with the cooling plate in there so plenty of clearance around the terminals
















And it fits, well sorta. I had to remove the ebrake cables and their brackets but there is enough adjustment in them I can relocate them. 
















With it sorta wedged in there it already sits quite nicely.


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## Qckslvrslash (Oct 29, 2019)

Pretty good day when goodies arrive in the mail. These are a Sendyne sfp200 and sim100

They are responsible for my current monitoring(sfp200) and detecting any hv leakage to my chassis(sim100) still a month or two off from wiring them in with a new job starting in a week but the list of parts I am waiting on to conplete my build shrinks every day.

Main things still in the mail are my bms, hv wiring supplies, battery cooling plates.


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## RustedB&B (Feb 15, 2021)

very clean and nicely done


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## Qckslvrslash (Oct 29, 2019)

Small Update
The bulk of my HV wiring supplies arrived this week. A couple items on backorder but I have enough to start spacing out and planning my contactor box. 









Also in an effort to get all the bits that need to be included in my wiring harness I picked up a double din stereo and some new speakers for the car. Spent the weekend turning my USDM single din into a double din unit. Japan had double din ones but they are an arm and a leg to buy if you can even find them. This was 20 bucks. 


























Last photo is kinda junk but I think with some finishing it'll look clean. The hole where the shifter went will have a nice can keypad filling it soon enough.


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## Qckslvrslash (Oct 29, 2019)




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