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Ian Hooper's RX7 Conversion

Posted: Mon, 05 Nov 2012, 23:51
by htial
Seeing your RX-7 backing out of the garage really makes me want to do my R33 Skyline...   ...But I've still go so much to learn first...

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 04:09
by coulomb
Great work as usual, Ian. Thanks.

Two comments though.

* I see you are following the common practice of putting the charger power inlet where the fuel cap was. You are using waterproof connectors, but it seems to me that these are only waterproof when mated, i.e. while charging. While it may be dry when you start charging, there could be times when you have to disconnect in the rain. Also, it seems to me that the connector could collect and retain rain water while parked, and cause problems later when charging. Fuel inlets are waterproof and indeed air tight, but the airtight cap generally gets removed with the rest of the fuel tank gear.

* I see that you use a mains relay to detect the presence of the mains, and you claim that this is more reliable than mechanical switches. This is well and good as long as the mains is on, but at the end of charging, some well intentioned person may turn the power off for you, rendering the interlock inactive. You might plug in somewhere that (possibly unknown to you) turns the power off after say 2 hours of charging. It is also possible, though admittedly unlikely, to drive off when there happens to be a power outage. Also, the four watts that the relay consumes seems excessive to me. (I know that AC relays are often like that.)

These are not intended to be criticisms, but your conversions are so polished that they are likely to be regarded as best practice and widely copied, so if there are considerations, I think it's best that they be mentioned here.

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 16:35
by BigMouse
coulomb wrote:* I see you are following the common practice of putting the charger power inlet where the fuel cap was. You are using waterproof connectors, but it seems to me that these are only waterproof when mated, i.e. while charging. While it may be dry when you start charging, there could be times when you have to disconnect in the rain. Also, it seems to me that the connector could collect and retain rain water while parked, and cause problems later when charging. Fuel inlets are waterproof and indeed air tight, but the airtight cap generally gets removed with the rest of the fuel tank gear.

* I see that you use a mains relay to detect the presence of the mains, and you claim that this is more reliable than mechanical switches. This is well and good as long as the mains is on, but at the end of charging, some well intentioned person may turn the power off for you, rendering the interlock inactive. You might plug in somewhere that (possibly unknown to you) turns the power off after say 2 hours of charging. It is also possible, though admittedly unlikely, to drive off when there happens to be a power outage.


Both these points are ones I've also been considering for my conversion.

I plan to protect my charge port (Likely a computer-style IEC plug) in the fuel filler by having it angle down and with a small shroud. The filler door will also have a modest rubber seal to protect it while driving in rain.

I'll be using a microswitch or hall switch with a magnet mounted on the filler door. The the controller will be locked out whenever the door is open, regardless of whether there is a charge cable there or not.

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 18:38
by zeva
Thanks coulomb, constructive criticism is always welcome!

I might have to do a bit of a rain test on the charge door. Perhaps if necessary I can get it to seal up a little better when it's closed (add an o-ring or something). In other cars I've used those Clipsal weatherproof charge plugs with their own cover, as seen in caravans, which seal up pretty well with or without a lead plugged in. But they wouldn't have fit so neatly.. or looked as pretty.. Image

And you are right, of course, that there are scenarios where using a 240VAC relay for charge detect is not perfect. It would be possible to drive off with a cable plugged in but switched off. (On the bright side, at least the cable isn't live as it gets torn out of the wall socket..)

In the early days I tried using car alarm style switches but found they got unreliable very quickly due to dirt/rust. In the EV Trial Focuses we used magnetic reed switches on the door (as BM suggests), and I guess they were pretty reliable, so long as the alignment is good.

I wonder what route the automakers are taking for charge detection.

PS: Are forum email notifications broken at the moment or is it just me?

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 18:43
by evric
These magnetic reed switches on the charge door are very important when using "Off Peak" charging as the power has (most times) already switched off when you come out to your car.

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 18:44
by evric
Hi Ian,

I'm getting "many" forum email notifications !

Ian Hooper's RX7 Conversion

Posted: Tue, 06 Nov 2012, 19:24
by Renard
BigMouse wrote:


I'll be using a microswitch or hall switch with a magnet mounted on the filler door. The the controller will be locked out whenever the door is open, regardless of whether there is a charge cable there or not.


While the AC relay is an interesting idea, I'd second (or third!) Coulomb's objection. Particularly if the fuel door is on the passenger's side where one might forget about it.
I've used a small, sensitive microswitch myself, but I can see that a Hall effect device could be more durable if well potted up.

Ian Hooper's RX7 Conversion

Posted: Mon, 24 Dec 2012, 00:10
by zeva
Hi all,

Big news: THE RX7 IS FINISHED! Hooray! Image

Well, basically. There are of course a few things I plan to add and I'm sure it'll be an ongoing project, but the car is now fully drivable, roadworthy (I think), and ready to start the licensing process.

I've put all the latest progress up on the conversion blog. Here are direct links to the new content, approximately in chronological order:

The water cooling circuit
The cabin heating system
Air conditioning (installation, plumbing and circuit/integration)
Fixing the instrument cluster (a real PITA!)
Installing the battery charger
Installing the front battery box
The start of a Licensing and Testing section

And here's a selection of pictures:

Image
The complete engine bay

Image
Lifting the front battery box in (with help from my father)

Image
A/C compressor belt drive

Image
The water cooling circuit

Image
Zivan NG3 charger installed

Image
Custom HotStart tank heater controller

Ian Hooper's RX7 Conversion

Posted: Mon, 24 Dec 2012, 00:25
by jonescg
Beautiful Ian! Just beautiful.

All the best with the licensing!

Chris

Ian Hooper's RX7 Conversion

Posted: Mon, 24 Dec 2012, 22:47
by coulomb
zeva wrote: THE RX7 IS FINISHED! Hooray!

Well done, Ian!   Image

Time to change the topic's title, perhaps?

Ian Hooper's RX7 Conversion

Posted: Mon, 24 Dec 2012, 23:45
by zeva
coulomb wrote: Time to change the topic's title, perhaps?

Good idea Image

Ian Hooper's RX7 Conversion

Posted: Tue, 25 Dec 2012, 16:31
by PlanB
Them blue headways in that blue engine compartment look so good man, great workmanship.

Ian Hooper's RX7 Conversion

Posted: Fri, 28 Dec 2012, 20:19
by AMPrentice
An absolute REVOLUTION and so much nicer than a Tesla even though I am Mazda Bias I really think this is so much better in so many ways.

Ian Hooper's RX7 Conversion

Posted: Sun, 06 Jan 2013, 20:39
by srs
Hi Ian

Congratulations on the great build!!
Looking forward to hearing how it performs, and thank you for the comprehensive build blog.

Cheers Scott

Ian Hooper's RX7 Conversion

Posted: Fri, 11 Jan 2013, 03:12
by EV2Go
Great work Ian, any videos showing performance?

Ian Hooper's RX7 Conversion

Posted: Fri, 11 Jan 2013, 06:37
by zeva
Hey, no new videos as yet, but some interesting updates..

I got a temporary movement permit and drove the car out to EV Works today (a 70K round trip) to get inspected, weighed, and to sort out the NCOP paperwork. Behaved perfectly the whole way there. One of the smoothest, nicest EVs I've driven.

But about halfway home, the Zilla started tripping out. Key off, key on and it would go again so I assumed a temporary comms error, but it got more frequent until it just wouldn't go and I had to get a tow home the last 5Ks! Now it's basically coming up with a comms error (1132) whenever I turn the key on.

So it is a bit sad that the car is out of action so soon after I got it going.. Image I've contacted Manzanita for support, hopefully we can get it sorted out without too much trouble or dollars. (Unfortunately the controller is quite old, despite only getting put in the car recently, so is well out of warranty.)

If I had to guess, I suspect it's electrostatic damage to the comms electronics from noise picked up by the cable between hairball and power box. In retrospect, the cable (and hairball) may be too close to the power box.

Ian Hooper's RX7 Conversion

Posted: Fri, 11 Jan 2013, 20:14
by PlanB
I stumbled across an eastern European EV build where the guy had kept the old ICE starter motor as a backup. Well that was my understanding, the text was a bit ESL. Anyway running from the 12v EV aux battery I don't think you could get 5km Ian.

Ian Hooper's RX7 Conversion

Posted: Fri, 11 Jan 2013, 22:53
by EV2Go
Hope its nothing serious. So putting your issue aside for a moment what was your first driving impression? Obviously down on power as you probably had it restricted but any indications of how it might perform?

issue = Low voltage related?

Ian Hooper's RX7 Conversion

Posted: Fri, 11 Jan 2013, 23:56
by zeva
Yeah hopefully nothing too serious.. Rob from EV Works kindly loaned me another Hairball to try but I'll wait to hear back from Zilla support before trying anything (in case it just damages the new Hairball too!)

Until the cutouts started, the car drove really well. I have the Zilla turned down to 1200A and will probably leave it that way for the first month or so of driving as a bit of a "run in" phase, but it certainly had plenty of power already - quicker than most cars on the road I'd say.

There was a bit more back-EMF than I expected, as in acceleration was a fair bit weaker by 100km/h, but not enough to be a concern on public roads or for autokhana type racing. On a high speed circuit or running quarter miles, it'd probably benefit from series/parallel switching - I might consider adding that later.

The car is 80kg heavier after conversion, which is a bit more than I expected, but hopefully not a problem as far as the licensing department is concerned. (Worst case scenario I could remove the rear seats and license as a 2-seater, but I'll try to avoid that option if I can.) The weight balance also changed by 1.5% rearwards, so it's now 51.5:48.5. Again, I expect this is a small enough change that the licensing department won't mind, or adversely effect the handling too much on the racetrack.

Ian Hooper's RX7 Conversion

Posted: Sat, 12 Jan 2013, 20:06
by zeva
A quick update, I heard back from Zilla support last night (decent response time) who had a few suggestions, mostly banking on a faulty comms cable (which we had tried swapping) but also suggesting swapping the Hairball, so I went ahead and put Rob's loaner in. Happily, the car seems to be running fine again with the new Hairball, implicating the old one as being damaged.

The car isn't licensed yet so I may or may not have just done a quick sneaky drive around the block as a quick test. But I'll get another temp movement permit early next week and try another trip out to EV Works or something for a more thorough test of the new Hairball - but it's looking like I'll just have to send my old one back for testing/repairs.

Nice to have the car running again in the meantime - thanks, Rob!

Ian Hooper's RX7 Conversion

Posted: Sat, 12 Jan 2013, 20:51
by jonescg
Forgive my ignorance Ian, but what is a hairball, in the EV sense of the word?

Ian Hooper's RX7 Conversion

Posted: Sat, 12 Jan 2013, 21:02
by zeva
Oh sorry, Zilla controllers have a separate power box and control box, with a comms cable in between. The control box is called the "Hairball", presumably because it usually has lots of wires coming out of it, resembling something a cat might cough up.

Image

Quite a relief if the problem is in there because it's much easier to remove and post back for repairs than the power box!

Ian Hooper's RX7 Conversion

Posted: Sun, 13 Jan 2013, 01:39
by EV2Go
Is there another diff option available for the series 8?

I worked out with 3.1:1 diff gears my trike will be doing about 2500rpm at 100kph, the point where torque starts to fall off.

Suspect because the car came with a gear box the diff may be a bit lower than optimal.

If you have plenty of nip off the mark you might consider a taller diff.

Ian Hooper's RX7 Conversion

Posted: Mon, 14 Jan 2013, 21:32
by zeva
Well, it is a possibility since the current diff is quite tall (4.3:1). However it is a very good diff (a strong Torsen-type LSD) so I imagine would be very expensive to change! Certainly much cheaper to add series/parallel switching, which would enable better high-speed performance without losing any low-end torque.

My original back-of-envelope calculations suggested I'd get about 0.8Gs of acceleration with the current setup, and I'm hesitant to lose any of that because I'm hoping it'll be enough to break traction at will.. Not because I'm a hoon, but because it'd get the attention of all the petrol-heads and car aficionados at the racetrack!

Ian Hooper's RX7 Conversion

Posted: Wed, 16 Jan 2013, 05:21
by EV2Go
4.3:1 is fairly low but not excessive (remember taller is closer to 1:1). The RX7 probably comes factory with 17" or 18" stock which would bring the revs down a fair bit.

Contrary to what logic would tell you, taller gears my provide a better burn out. You would think the mechanical leverage of lower gears (I.e. Greater torque multiplication) would aid it, but only in breaking initial traction.

Because the wheel speed is lower at the point the torque falls off it provides greater opportunity for the tread to grip, where as with tall gears if you have enough initial torque to break traction the tyres will have a harder time re-gripping.

Once you up and running it might be worth trying to borrow some larger diameter wheels just to see if the torque you have available might be happier pushing taller gears without the expense of changing the diff.

But series - parrallel is worth considering down the track too.