[Qckslvrslash]

This project started just over a year ago and has been slow going but bit by bit I am making progress. I am going to slowly post all the work on it and catch anybody interested up.

This was the car as I bought it

Wasn't running but for what I had planned. I got a steal for sub 1k. Oddly before pulling anything apart I fixed the motor first. Needed a new distributor and main relay was gone.

 

[Qckslvrslash]

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

 

[Qckslvrslash]

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

 

[Qckslvrslash]

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.

 

[brian_]

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?

 

[Qckslvrslash]

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

 

[Qckslvrslash]

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.

 

[brian_]

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.

 

[brian_]

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.

 

[Qckslvrslash]

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.

 

[Qckslvrslash]

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

 

[Qckslvrslash]

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.

 

[Qckslvrslash]

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.

 

[remy_martian]

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

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

 

[Qckslvrslash]

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

 

[zrickety]

Awesome build, subscribed.

 

[Tremelune]

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

 

[Qckslvrslash]

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.

 

[wjbitner]

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.

 

[Qckslvrslash]

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.