1988 Honda Prelude conversion - fastest build log ever.

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1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 05 2019 1:32am

Well it's only the fastest build log because it's the first time I've started a build log here on Endless-Sphere. If you want to read the whole lot from start to finish, look here: http://forums.aeva.asn.au/viewtopic.php ... 502#p67017
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But in a single post I'll document it here.

A friend asked me to convert her 1988 Honda Prelude, the one with the mechanical 4-wheel steering. I didn't want to, but suggested a few folks who might. They all said no, so she came back to me and begged me to do it. I warned her it won't be cheap, and it will take ages... and she said OK great!

So we took a few measurements and worked out what might fit, and made a selection of parts to go in. We decided on 24 kWh of LiPo pouches with a liquid cooling system to improve cell longevity. It wasn't going to be a race car, just a daily driver with a decent range for a sprawling metropolis like Perth.
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I'd just bought my house, which has a big shed and room for a hoist. Once the hoist was installed, the car went up and out came the oily bits (December 16th, 2018). I had hoped to fit the whole battery where the fuel tank was, but we could only fit 6 modules there, and the last two modules would either have to go up the front under the hood, or in the spare wheel well of the boot. In the end, the boot was the only viable space.

The motor was a Greatland PMAC motor and controller, good for 60 kW peak and 30 kW continuous. Enough to get you rolling smartly, but not set the world alight. It was mounted to the original 5 speed manual gearbox. We retained the clutch because the gears are required for acceptable performance on take off.
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It took it's first drive around the block 9 months later with just 6 modules installed.

https://www.youtube.com/watch?v=BcPlGSgthig

I now have all 8 installed, so the range is a comfortable 140 km or so. No real change in power, but we can change that later.

I initially used a sheet of aluminium honeycomb composite for the floor, but I wasn't happy with how fragile that stuff is should you ever drive over a big rock or something. So it has since been replaced with a floor of 6 mm plate aluminium. The flex gives rise to about a 6 Hz oscillation under certain circumstances, so hopefully the new coilovers will address some of that.
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I'll have it on display at the Mosman Park Mens Shed craft fair this Sunday for Perth folks.

Basic stats:

Original chassis: 1988 Honda Prelude, mechanical 4-wheel steering, 2 litre petrol engine, 120 hp.
Original Tare: 1100 kg
New Tare: 1200 kg (or thereabouts)
New Power: 60 kW (80 hp)
Motor - Greatland PMAC liquid cooled motor, full use of front wheel drive transmission and differential.
Inverter - Greatland 3-phase inverter, liquid cooled.
Charger - 6.6 kW TC/Elcon charger, CAN controlled (eventually) single phase, 240 V AC, liquid cooled
DC/DC converter - 1.6 kW TC/Elcon, enable (12 V) activated
Charge port - Type 2 (mennekes) with AVC2 control. Doesn't work with most public charge points for some reason.
EVSE - Open EVSE kit with a 3-phase 32 A, 5-pin socket on the end.
Battery - 24 kWh high energy, liquid cooled LiPo pack. 96s10p of 7000 mAh cells from GE Battery, China. Assembled as 12s10p blocks using the screw termination kits I always use, plus liquid cooling plates on the underside of the cells. Nominal voltage: 355 V, fully charged at 400 V. The coolant is just water/glycol, but it is passed through a heat exchanger which is chilled with refrigerant from the air conditioning.
BMS - ZEVA EVMS3 with CAN Bus, current sensing and TC charger integration (very nice).
Range - in typical 60 km/h traffic, about 150 km. At 100 km/h sustained highway driving, about 110 km.
Regen - yes, but it's not working properly at the moment. About 7 kW of regen at the best of times.
Top speed - maybe 120 km/h in fifth, but it's not set up properly to get full power.
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It will have been about 1 year since we started work in earnest, but hope to have it licensed before Christmas.

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by Hillhater » Nov 05 2019 5:25am

Very nice work jonescg, a tidy conversion.
You are a talented and brave man to take on the responsibility for all that work.
What do you estimate the total cost of the conversion might be ?.. parts and labour ?
She must be a “good” friend, or were you on “mates rates” :wink:
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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 05 2019 8:31am

Hillhater wrote:
Nov 05 2019 5:25am
Very nice work jonescg, a tidy conversion.
You are a talented and brave man to take on the responsibility for all that work.
What do you estimate the total cost of the conversion might be ?.. parts and labour ?
She must be a “good” friend, or were you on “mates rates” :wink:
I couldn't charge enough...

There's about $35k worth of parts, and I charged about $5k for my sweat. But being my first car conversion I viewed it as a learning experience too. I could probably do it all again in a third of the time, but the parts list is still an expensive one.

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Post by Hillhater » Nov 05 2019 9:20pm

Yes, unlikely to ever be financially viable once you add the cost of a suitable “host” car.
And i guess the battery is a major part of that, both cost and labour.
Would if be any simpler/cheaper if you could source donor parts from a wrecked EV (Leaf, Ionic etc) when they become more common ?
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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 05 2019 9:41pm

That would have made the cost lower, but they simply wouldn't fit. This was a bit of a no-compromise car - all 4 seats were retained, only 100 kg over the original tare, and (almost) all boot space retained. No way Tesla modules would fit, and Leaf modules would offer half the energy for the same space occupied. About the only way to make a long-ish range conversion is to build a custom pack with high energy density cells designed to fit exactly in the space available.

The motor and controller were chosen because they were the right price, not because of performance. But they are fairly efficient. The cells are a bit of an unknown - how long they'll last is uncertain, hence the liquid cooling loop to ensure things stay within a happy range.

The battery was a fair whack of the labour, but no more than 40%. It was easily 2/3rds of the cost though. 208 Wh/kg makes it completely viable to have a 150 km range car - if we'd used LiFePO4 it would have been a 90 km range car, but cost a lot less.

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 06 2019 7:38am

I did a slightly longer drive today - 95 km, but most of it was at 70-90 km/h with the odd stretch at 100. It seems to pull 18 kW at highways speeds, which is pretty good for a conversion I think.

8 kW - 60 km/h
10 kW - 70 km/h
13 kW - 80 km/h
17 kW - 90 km/h
19 kW - 100 km/h

Although this is on fairly flat roads, mild days and no other auxiliaries (or passengers). I think this car has at least 140 km of highway range, and probably 160 km of city driving!

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by neptronix » Nov 07 2019 1:24am

24kwh of lipo, jesus christ.. got any burnout vids, Jones? :mrgreen:
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 07 2019 1:26am

neptronix wrote:
Nov 07 2019 1:24am
24kwh of lipo, jesus christ.. got any burnout vids, Jones? :mrgreen:
Hehe, it's the high energy density stuff, not the high C-rate stuff. Anyway, I think the motor/controller is the limiting factor. It lights up the tyres in 2nd pretty well, but pretty docile really.

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by Hillhater » Nov 07 2019 4:12am

jonescg wrote:
Nov 06 2019 7:38am
....... but hope to have it licensed before Christmas.....
..........I did a slightly longer drive today - 95 km, ........ :shock:
:o ..OK, oK.. i will just assume you have a big private back yard ! :wink: :bigthumb:
PS.. What are the dimentions of that pack/modules ??
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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 07 2019 8:18am

The car is technically licensed, it's just had modifications which haven't been signed off yet ;)

The modules are 12s10p LiPo, 7000 mAh cells. Each module is 194 mm wide, 310 mm long and 168 mm tall, weighing 19 kg.
I have 6 in the fuel tank space and 2 in the spare wheel well of the boot. No spare tyre any more, but we can get a space saver, or call the RAC...

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 07 2019 8:50am

jonescg wrote:
Nov 06 2019 7:38am
I did a slightly longer drive today - 95 km, but most of it was at 70-90 km/h with the odd stretch at 100. It seems to pull 18 kW at highways speeds, which is pretty good for a conversion I think.

8 kW - 60 km/h
10 kW - 70 km/h
13 kW - 80 km/h
17 kW - 90 km/h
19 kW - 100 km/h

Although this is on fairly flat roads, mild days and no other auxiliaries (or passengers). I think this car has at least 140 km of highway range, and probably 160 km of city driving!
And today I took Roe Highway home, which is a motorway, effectively. In 5th gear it sat very comfortably on 100 km/h and consumed a mere 13.5 kW.

That's 135 Wh/km, or enough to give at least 160 km of highway range! I am impressed. :D

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 07 2019 7:23pm

Sick!

-methods
jonescg wrote:
Nov 05 2019 1:32am
Well it's only the fastest build log because it's the first time I've started a build log here on Endless-Sphere. If you want to read the whole lot from start to finish, look here: http://forums.aeva.asn.au/viewtopic.php ... 502#p67017

20180705_172252.jpg

But in a single post I'll document it here.

... ... ...

20190902_070855.jpg

It will have been about 1 year since we started work in earnest, but hope to have it licensed before Christmas.
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by neptronix » Nov 07 2019 8:12pm

160km is pretty nice.. considered doing some aerodynamics mods? IE bottom panels, gap sealing, rear wheel wells, etc?
The ecomodder forums could be real helpful here.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 07 2019 8:29pm

neptronix wrote:
Nov 07 2019 8:12pm
160km is pretty nice.. considered doing some aerodynamics mods? IE bottom panels, gap sealing, rear wheel wells, etc?
The ecomodder forums could be real helpful here.
Wheel spats would make a big difference, but being a 4-wheel steer car it might be tough to mount. I think there is something to be gained from putting a corflute shield on the underside as the battery pack adds about 25 mm to the windswept area. The car is fairly low, but not CRX low. On Monday I'm going to try and turn the regen up to 11. The owner lives halfway up a big hill, so it sucks to have to dab the brakes a lot and not get anything back.

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 07 2019 9:06pm

Angle Grinder to remove 1lb here and there?
If you go at it long enough you may be able to remove 200lbs :wink:

Back in the day I spent a week upside down in a civic removing all of the sound dampening...
Then the heater, AC, extra seats, all unused bolts, all internal trim...

Cut the dashboard in half... Dropped the spare tire...

... End result was foggy windows and getting stuck with a flat.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by TheBeastie » Nov 09 2019 1:38am

Looks great, well done! :)
I give my own personal thumbs up :bigthumb:
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Last edited by TheBeastie on Nov 11 2019 12:03pm, edited 2 times in total.
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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 09 2019 4:04am

Just had the coilovers installed. It rides like a million bucks! No wobble-board, decent ride height, no wallowing or roll, but not a harsh ride either.
New ride height.jpg
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All I need to do now is get the aircon installed and it's ready to get handed over.... once I have a few more drives... :shock:

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by nicobie » Nov 09 2019 2:42pm

VERY nice. Clean installation!

I've been tempted to convert a pickup truck but don't have the energy I used to have.
Image

May your tote always stay tight and your edge eversharp :wink:

my eTownie build thread: http://endless-sphere.com/forums/viewto ... =6&t=23701

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 10 2019 11:18am

I would be interested in hearing the AC Install side notes.

Automotive A/C is almost accessible to the DIY-GUY... with the less-gnarly refrigerant kits available at any Auto Parts store.
High Pressure side
Low Pressure side
Pair of gauges
Can of juice

For Home Refrigerant the industry is in LOCKDOWN - especially if your compressor likes one of the old flavors of gas.

...

With EV's I had always assumed there was a non-belt driven AC
Which sounds handy for Projects
No idea.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 10 2019 7:41pm

methods wrote:
Nov 10 2019 11:18am
...

With EV's I had always assumed there was a non-belt driven AC
Which sounds handy for Projects
No idea.

-methods
I went and bought an aircon compressor which runs off the battery pack (200-400 V DC) and is controlled by PWM or +12 V enable. I have just decided to use the +12 V enable, using the same 12 volt supply normally used to activate the clutch on the compressor. I also have an Arduino set up to read battery pack temperatures and enable the aircon compressor should the cell temperatures exceed say, 28'C. The occupants can also apply the aircon by pressing the button, but basically if it's hot enough for the battery, it's hot enough for the humans. It will mean my wonderful range figures will drop though. Speaking of, I drove to work in it today and it only used 18% to do 40 km. If these trends continue, :bigthumb: ehhhhhhhh!

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 11 2019 1:23am

Thanks for sharing!

I need to build another chiller (larger Cold Water Reef Tank) and I need it to have 100% up time.
I am thinking of building it from a pull-down EV Air Conditioner,
Powering it from a low capacity, high voltage pack,
And pass-thru running it daily off of a Charger

Totally impractical, but a way to start learning about the core changes between the ICE vehicles and the EV's.

... Looking forward to seeing your updates. Nice choice on the car - I love the Prelude. Fine Vehicle.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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methods   10 GW

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 11 2019 1:25am

Image

Are you using the internally shielded wire
(for example 2AWG with a shield built in)

Or are you using something more like Welding Cable?

Tinned or bare copper?

Do you get any noise or interference with your Radio, Cell phone, or other?

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 11 2019 1:30am

Image

Could you share more about how you seal off the pack?
I see a lot of bare copper. Are you using grease?
Do you use any descant?
Are there weep holes?

Is there a membrane, or if it is vented how do you manage moisture collection while the pack temperature cycles?

I presume that as the pack gets hot it either pressurizes or vents out.
I presume that when the pack gets cold it breaths in.
Can you pull the battery down in less than an hour for inspection?

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by jonescg » Nov 11 2019 2:06am

Cables - mostly 50 mm2 double insulated flex. The only shielded HVDC cable is the stull already in the orange conduit.
No issues with EMI anywhere really - the biggest source is the motor and controller, and those cables are less than a metre long.
Battery pack can be dropped out in under an hour, but if not for the extra two modules in the spare wheel well, it could be out in 15 minutes.
Yes, lots of copper - all the better to conduct electricity with :) I used Alminox grease on all copper conductors. The polycarbonate modules are not waterproof and sealed, but the fiberglass cover which goes over it is pretty waterproof and well sealed. There are silica gel desiccant packets in all modules. The pack is able to breath through some small holes on the top of the pack. There is also a drain bung should coolant ever leak. The cells themselves are separated from the coolant by an aluminium coolant maze, and are adhered to the plate with thermally conductive (electrically insulated) epoxy.
The build log I linked in the first post is a good place to find all the relevant images and information.

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Re: 1988 Honda Prelude conversion - fastest build log ever.

Post by methods » Nov 12 2019 1:53pm

Wow. . .

I dont think folks have any idea how Valuable of a contribution it is to share this kind of stuff. I have seen millions blown just in finding the lessons in the paragraph above.

Thanks man :wink:

... Any College folks building a rig would be WISE to take the time to understand the Who-What-When-Where-Why of the engineering above. Clearly a result of expensive lessons learned.

-methods
Increasing battery voltage and controller current limit will result in a non linear experience

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