924Board.org

[unheardofinstruments]

Some members asked me to start a thread concerning the project I have going restoring a 924 martini for an electric conversion so here goes;

Being under capitalised for such a venture it might take a while before it is done but I may as well start with some pictures of the restoration first. Here it is soon after I got it back home and off the trailer and started finding where the rust was and picking off the flaking paint. It had been resprayed black but the surface prep left a lot to be desired, I even found dirt under the flaking topcoat on what seemed like a pretty decent factory finish.
The thing had been stripped down pretty far already which I thought at first was bonus, then I realised how much else that I would need was missing and the search for parts begins.








That last one is another reason why the 924 is a great car to convert, the room under there will have a lot of batteries and the motors driving the CV's through a toothed belt reduction drive at about 6:1.

The reason I chose the 924 after doing a bit of research on the net and in books (`Build your own electric vehicle' by seth Leitman and Bob Brant is highly recommended reading with loads of helpful calculations and advice to plan it) was that it was light, streamlined (drag coefficient of .31 is phenono menal for those days) stylin!, and simple, ie; no power steering (requiring an oil pressure pump), electrical overkill functionality and only a vacuum pump needed to boost the brakes (in the absence of the donk vacuum.)

I am planning to strip as much weight as possible so the bonnet and hatch are prime candidates for replacing and fibreglass panels would be great. I plan to make a fibreglass bonnet skin with a bunch of solar cells embedded in it that I got as factory seconds and have been tabbing together for $1 a watt. The russian monocrystaline flexible panels I have on my electric full fairing recumbent roof are light, efficient at high temps and low light, but expensive but could be stuck over cutouts or on the roof. It would take ages to charge but every bit would help extend the range and it could charge while in the carpark when I am shopping/in town.



I had hoped my old tarago van was going to putt on but it started terminal phase with both gearbox selection problems and ever decreasing power and increasing smoke and has entered the N.E.R phase. (perhaps it should go electric too.)

Enter my new car, which I found on ebay with a whole bunch of parts I needed for the resto; 9 rims on and in it, headlight bits, tyres, and a whole bunch of engine parts and electrical stuff I didn't need but for $2025 with 8 months rego but over three before I got it home and partly fixed. It seemed too much like everything I needed until I had the electric one finished, my last ever oil burner?



First realisation, having to rewire the thermo fan to stop it overheating in stop start traffic made sense of the thin film of oil on the water, the guy had overheated it and blown the head gasket, not too big an ask to fix on a nice uncomplicated engine, wobbly steering was easy fixed by swapping the two very buckled rims for good ones from the back.

Then on the freeway that night sudden horrible grating and sideways lurching, almost going under a passing semi I get to find out the guy hadn't put the split pin in the lhs castellated nut holding the brake drum on and it unwound itself. yikes. I had to take a spacer out and jam my keyring there, limp into nearest town, next town, next town looking for bearings and making an awful metal on metal racket. Heroes at the Bowral engineering shop had them and the seal but the main one not in the extreme (code e) ruggedized model required so camp out for two days and freezing nights in the front seat wrapped in a seat cover until I could get them put in, luck of all things the guy from the euro motors workshop in in the whitsundays had opened up a new workshop (only not booked out garage in town) AND had the special star shaped tool to undo the bolts in the CV's and he was a great source of tips too, knew them well. Rollin!

...until karuah where it ground to a halt on the inside of a sharp bend entering town. Uh oh, stranded. No help there for european car trouble, quick phonecall to my hero in Bowral and he correctly diagnosed it by phone as the points closing down. Buy a screwdriver, eyeball adjustment and we're away instantly, phew.

So I made it home, bought balljoints and a head rebuild kit and just a day before I started on it hit a wallaby which lifted the front and sent me into a tree. Writeoff. How I feel like the guy who knocked over the venus de milo and broke her arm off, such a shame.

I've stopped cringing when I see it but still wish it never happened, I was in love already after 5 drives even with loose front end and buggered shocks and all the dicky electrical shenanigens with the corroded relay box... it was a pleasure to drive.

On the bright side I now can turn the crashed body into a trailer by cutting the crumpled front off and I could then make it a range extender too.

Should look weird especially if I can get streamlined with the body, I am thinking a lycra sock between the trailer body and the back hatch might give it a bend and stretch limo effect. I did get sent a photo of something similar after mentioning this on another thread.

Options considered so far include; I have a hydraulic pump/motor lying around and with an added accumulator could do hydraulic regen braking,...but then a twin 50cc RC plane engine I have puts out 4.7kW and probably about the same in exhaust heat some of which could be captured with solid state thermal generators to recharge the battery as well as drive an axial flux generator, and drive the wheels too. I could add more batteries under it and have a motor/generator/regenerator setup on the CV's, food for thought...might be nice to have detachable luggage space on the back, room for more panels, a bed maybe for camping,... ?

But at least now I have all the parts I need for the electric project and more. See
http://www.924board.org/viewtopic.php?p=324554#324554
buy some off me so I can get my motors.

For the car I have my eye on two Agni 95R axial flux permanent magnet dc brushed motors from india. (3000 shipped which compares well with the antiquated dc induction motors most people use which weigh 3 times more and have big back emf) Cedric Lynch has started getting them made there after separating from Lynch motor company UK and also the german version PERM and the e-tek from china. They won the Isle of Man motorbike race with an electric bike powered by one. I am hoping an even more powerful one they have in the pipeline will be ready by the time I get the dough together. They drove a suzuki swift with two motors in it over a mountain with 4 people in it so it will work but more watts is more torque and more fun right?

I also need a battery pack; $6000 will give me about 200km range using new LiFePO4 batteries and although more expensive initially (and dropping rapidly and with improved chemistries and supercapacitors barking at their heels) they should last about 3000 charge cycles and still be 75% capacity and way outlast lead acid by a factor of six and weigh a quarter as much. That is daily driving at 1cent a k in juice for about 10 years. This is what has made electric cars much more viable, nanotechnology, investment in the billions by laptop battery makers, china mass producing them and electrifying their bicycle car and truck fleets on mass. Guy Negre's compressed air car is now being manufactured by Tata motors india and for about ten grand is about the same cost as a chinese plugin electric car. I have been on the waiting list for one for about 9 years but the batteries won. You will see them more and more over the next decade and europe and america even have govt initiatives to give rebates and incentives for going electric. It will cost me over 10k by the looks of it to build my own but if I can handle lower range like 100ks (before I put the trailer on it) could be substantially (3-5K) cheaper at the outset.

I like the idea of no oil changes, fuel, noise, spark plugs, filters, leads, belts, coolant, points, injectors, worn valves, rings, greasy engine bays, smell, running at the lights standing still, exhaust repairs, gaskets, welsh plugs... the pile of parts I don't need is huge and you can see how little was on it anyway.

Replace all that weight with batteries and a nice efficient motor with two moving parts and now with IGBT power switching (like in the new lightweight switchmode powersupply arc welders) a rugged high tech electronic controller for them is a vast improvement over the old dc chopper circuits we used to use way back in the late 1800's in the very first ever cars (yes they were electric ones!) and the big arrays of smoldering mosfets of later years. Electric is coming of age. The fastest drag car on the planet atm is a VW beetle electric.

Already over 90% efficient it should drive the production of very light streamlined cars, battery improvements and low rolling resistance tyres because the biggest drawback is range, however charging stations, pump out electrolyte and replace, super fast charging battery tech, supercapacitors, molten sulfur batteries, you name it, is competing for a place in the coming infrastructure and being allowed to finally too.

Ever see the film `who killed the electric car?'

scroogle.org (screw google) the EV album and see the hundreds of people who have converted cars already.

It is getting long so I will post a few newer photos and a few links next time. Looking forward to hearing some opinions and ideas in the following dicussion, hope it got the cogs whirring. cheers
ron

[ideola]

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_________________
erstwhile owner of just about every 924 variant ever made

[924aussie]

Way ahead of you , already built more in pre production stage

http://www.trevipedia.net

In 2010-2011, Team Trev drove a modified version of Trev around the world. This version had a 13 kWh battery, which gave it a range of up to 250 km.
_________________
green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold

[unheardofinstruments]

Images still don't appear may have to move them to a different url as I think where they are has a password block, hmmmm, soon

Love the trev. I'll bags one of the next ones. How much $?
There was also a very cool 3 wheeler built up here in ballina by some aircraft fixing dudes that had a motorbike engine but would have made a superb electric vehicle, fully teardrop shaped upwards curving at the back, very sleek. If I had the dosh I would buy an Avion kit car. 119mpg using a normal VW tdi instead of the usual 62 and gull wing doors are perpetually cool.
http://www.100mpgplus.com/technology/index.html

here on the shoulders of giants drive we (or more like 20 000 dwarves)
_________________
There is more to heaven and earth than is dreamed of in your philosophy...

[unheardofinstruments]

The stripping is continuing apace and I sealed the rear lights back into the `trailer' and got the hatch working. Once I get the engine and tranny, tank, torque tube out I will be cutting it in half and welding the towing parts on so I am scouting steel and a hitch mechanism and making measurements and getting greasy.
The martini is coming along, been working on the locks, lights, hatch, paint, switches, steering, rear wheel bearing, seats and the trim bits inside and the stereo wiring. Still a lot to do. Still too broke to get more electric parts but hopeful that might change. I have found high discharge LiFePO4 cells at $1.1US per Ah which is the best price so far but still $7-10k depending on cell type (3C or 15C) for the battery pack looks probable if I want to get about a 200km range so some saving to do. Lots of interest in the infernal combustion engine parts.

[Mr Bitey]

This will be a fun project to do... Just got to have deep pockets.
_________________
Tom
___________
1979 924 NA
1979 924 NA - Parts car

[joecitizennn]

99% of posts here I don't read, the few I do are the short and to the point type. Therefore I was amazed to find myself reading this entire rambling post. Bravo man!
_________________
87 924s
88 924SE gone
447 hp cgt clone
87 924S gone
84 944 sold
83 944 sold
89 turbo S LSD, ABS etc
86 951 white rocket
85 944 sport everything.
84 944 sold.
87 944 sold

[Joes924Racer]

Wow.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[Khal]

[fiat22turbo]

If it were me, I'd do something similar to what a local person did for the $2009 GRM Challenge. He built his own Hybrid. For under $2000

http://grassrootsmotorsports.com/forum/grm/west-coast-2009-challenger-awd-fiero-hybrid/10519/page1/

In his case, he used a Fiero, kept the ICE engine in the rear and stuffed the front with an engine/transmission from an Electric S10. The electric motor was powered by two salvaged Prius battery packs and controlled by an appropriate controller.

He then drove it to San Diego to compete with the WestCoast Challenge and then Florida to compete at the main challenge and then back to Portland. He's since made improvements to the car.

So in this case, perhaps leave the stock 924 drivetrain in place and see if you can attach an electric motor in such a way to help provide drive to the car. It won't be easy, but neither is a pure electric conversion.

The potential gains in fuel economy could be quite impressive.

One thought I had was perhaps if one were to combine the Audi 5-speed used in the 924S/944 with the guts of a Quattro 5-speed (slight differences in the case design for the linkage passthrough) then you could have a switchable outdrive for the rear that perhaps you could connect an electric motor to?

The obvious concern would be room for the gas tank and the motor, plus the weight balance change.

Moving to a fuel cell would help, especially if you built one to fit into the rear seat area with an appropriate firewall/bulkhead around it. If you used Prius battery packs, they could live in the engine bay to help keep the weight balanced front/rear.

Another thought would be to attempt to use standard Rabbit front uprights and small electric motors to drive the front wheels. I haven't found electric motors small enough to fit, nor do I know if reversed Rabbit knuckles would work, but its an interesting thought.

It would be like the Porsche 911 Hybrid race car that was recently kicking the butts of top of the line LeMans cars out of the corners. Seriously, at Petit LeMans, the Audi, Peugot and other drivers complained about how quickly it accelerated out of the corners when they were attempting to pass it. They couldn't keep up until further down the straight.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[unheardofinstruments]

I like the idea of making a hybrid but figured the idea was to get a very small light engine working at peak revs charging with a very efficient generator like an axial flux design at the pack charging voltage hence the idea of the 50cc twin cylinder aircooled 2-stroke in the powerband (tuned pipe). I calculate the 924 would use about 7.5kW to keep highway speed on level ground with a lot to be gained by using low rolling resistance tyres and further mods for streamlining like underbody pans and weight loss using fibreglass panels etc. like for race cars. The 50cc engine produces 4.7kW and weighs almost 600g with the generator set maybe another 2kg, output lets say 90% efficiency 4.3kW exhaust/generator 1kg. maybe another 700W (who knows?) by the time it cools that's 2/3rds of highway power already.

There is more than enough torque at any speed for the rest so the electric drivetrain wins hands down in efficiency. A 10kW motorbike engine would be pretty small.
If thermal generators could harness some of the energy from exhuast heat (another 10kW available there to work with) and solar panels, (why not?) short bursts of petrol power would keep you going down the highway for ever and the overall efficiency would be good. The Prius is less efficient than many ICE only cars mainly due to it's whopping ICE and thus weight. Axial flux electric motors of equivalent continuous output would be 18kg (peak output being double)
Ecomodder.com has a bunch of hybrid experiments including driving the ICE via the timing belt pulley on a suby forrester with an electric motor but the savings weren't very impressive. Electric drive is the most efficient way to move, ask a locomotive or a ferry. Now power storage is getting good lets harvest energy, so many renewable options that the mind boggles. How many can you think of?
_________________
There is more to heaven and earth than is dreamed of in your philosophy...

[unheardofinstruments]

Having read the entire build log on the Fiero Hybrid I have to say the guy did a great job, amazingly tight fits all round, serious dedication and workload, amazing engineering skills... but the ICE ain't worth the weight, he is now looking to find a lighter more powerful one to put in it and his next project was very light. He would be better off putting another electric setup on the rear for drag racing as the one on the front made the ICE look like the weak link it really is.
I am still dubious about the hybrid as seen so far, impressive gains in petrol efficiency to me mean from 8.9L per 100kms to zero.
Thanks to the laptop companies paying hundreds of billions into battery researchers pockets we have some great battery technologies emerging and LiFePO4 etc are already cheaper than lead acid by a factor of six if you factor the recharge cycles in(2-3000 which is about ten years driving to 80% capacity when they would still do for solar house use) and being 4 times lighter per Ah already I think the batteries have already made the electric car workable despite the efforts of oil companies and lead acid battery makers to stop innovation so far.
Lead acid always sucked; high self discharge rate, weighty, don't like heavy use or going very flat, don't last, inefficient to charge ...hence why the electric car was limited so far. There are several promising incremental changes and many alternative chemistries looking promising but the nickel titinate supercapacitors look most likely to win to me. It is just mighty scary to think short circuits though!
There are some aussies making a 4x4 into a 2+2electric which is easy, just take out the rear prop shaft and shorten it so you can mount an electric motor behind the transfer case. They are using a cheap light `SUV' which has a 130kg alloy motor and a pretty light body (for a 4x4 anyway) a Prius NiMH pack and standard DC motor. I will be curious to see what kind of savings they get when it is done but rolling resistance being the constant drag is the killer there which is why light is good and narrow profile tyres pumped up to maximum help. Wind resistence becomes the exponentially bigger factor at speed and at around 45mph is about equal to the drag from rolling resistance and at 65mph it is around double for the average car.
Ecomodder.com has a bunch of info on mods for efficiency from people who have tried it and none of the hybrids were very impressive.

Hardly anybody seems to use the axial flux permanent magnet motors which are much (4x) lighter for the same power. One guy Carl from LA had scaled up an LRK style motor from electric radio controlled plane world and used it on a motorbike (and he said he could make me one for $2500US but the Agni ones are 950 pounds so two are 3000 posted)
see this link to see what I mean;

http://www.aerodesign.de/peter/2001/LRK350/Warum_dreht_er_so_eng.html#Anker1164462

which is another innovation crying out to be taken up by the EV makers. If my pockets don't deepen I might get impatient enough to build my own axial flux overclocker giant LRK motor in a pancake arrangment (rather than just buying two nice Agni 95R's.) I bought a book on how from a Danish guy who built his own for a motorbike motor from ply and carbon fibre and it isn't rocket science. A few small changes and it could be an overclocker too and have 6 times the torque and turn 7 times slower (which would save me the current headaches building a 6:1 reduction drive for the Agni's) I probably will start making a generator first up for the trailer/RC motor and see how it goes. A bit of calculating to get my head around re. copper coil lengths/wire thickness, amps, power, flux density, rpm... Haven't attempted maths for years...

To hybridise my motorised bicycle I used a front hub motor which are available for electric cars too and easy to put in but I don't like the idea of the potholed road like 'round here and the inevitable effect on them.
A cog and chain on the driveshaft would be pretty easy like the permadrive (whatever happened to them?) and people have tried the running an elactric motor driving the motor via the alternator belt but I can't help feeling a tiny (decently efficient, why is that so hard to find?) generator is all you need as a range extender and the electric drive-train is so superior it is all you need to move it (maybe vroom vroom through the stereo too for those who like a nice exhaust note)

[unheardofinstruments]

I have access to EPC corporation IGBT equipped controllers at a discount if anyone is interested.

Thinking hard about making my own motors again. Necessity being the mother of invention and lack of funds being the motivating factor in make do of all kinds.
Bought more parts for the restoration and still stripping `the trailer', working on repairing the rust in the fenders by chopping useful bits off the bent ones. Parts are occasionally selling. Alloy is 6 bucks a kilo so getting tempted to scrap some motor stuff to raise some funds and make some progress. Still lots of restoration work to do anyhow in the meantime.
I put some of the photos on a squidoo lens for now

http://www.squidoo.com/DIY-electric-vehicles

[unheardofinstruments]

www.ultramotive.com.au
also
Lightning car company in the UK is making a supercar using Alithion titinate cathode Lithium batteries, 10 000 discharge cycles and low heat so charge in 20 minutes.
These are 100 000 dollar + cars but 400kW! wow.
_________________
There is more to heaven and earth than is dreamed of in your philosophy...

[Joes924Racer]

Waite 10 20 yrs when theres alot of electrics on the market and alot of
the worlds great cities have taxes in place per mile you drive.. from what ive heard it could be anywhere from a few pennies to 10 cents per mile.
Its right around the corner.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.