Electric Vehicle Conversion - the X7 (RX7)

Whoops! Time flys

2011-09-08T21:30:00.000+10:00

At present the car is on jacks sitting in the garage. The thing is that I've been inundated with family and job concerns. I haven't given up - just putting the project aside for awhile. Sorry if I've dissapointed anybody but for the past year and the next few months it'll have to wait. As soon as I get back into it I'll carry on the blog.

12V battery shelf & video part 3

2010-02-06T14:47:00.003+10:00

I've now mounted the front battery box. I used the existing radiator mounts at the front and have drilled through the chassis rails aft of the box to put mounting bolts. However, for the chassis bolts I've put a pipe sleeve over the bolt so when I tighten it up the nuts it will not crush the chassis rail.

This I couldn't show in the video hence the photo to the left.

I've also mounted the 12 volt battery shelf using one from another car and welding more mounts to suit. I was going to hang it from an aluminium shelf over the top of the motor to hold the controller etc but thought that a heavy lead acid battery swinging off an aluminium plate wouldn't do too well as it would warp or buckle.

So, I'm using the bolt I put through the chassis rail for the traction battery box mount andI have purchased a longer bolt (grade 8.8 of course) to replace one that was for the steering assembly (photo left) and used for the 12 volt battery shelf.

As you can see I've used the traction battery box mounts as well. With the shelf firmly mounted I'm also using a dropper strap that will go up to the aluminium plate above the motor but I'll have a reinforcement rail to assist with weight distribution.

Mains plug connection - Video

2010-02-06T14:17:00.000+10:00

I'm getting the hang of this now so here is a video of the mains plug connection that I had pictures of in a previous section.

Intro Video Electric-RX7 Part1

2010-02-06T13:47:00.000+10:00

I've repeatedly been asked if I do any videos and I keep saying"sorry, no I don't". Well I've got a new phone and I've worked out how to take short videos with it, upload to Youtube and embed to the blog. The first is a quick intro to the project.

Seat Ibiza EV

2009-09-19T20:32:00.000+10:00

Today has been an interesting day. We went and had a look at a Seat Ibiza electric vehicle which is in the final stages. It has an Impulse9 (slightly smaller brother to the Warp9) by Netgain, a 1000Amp Logisystems/Netgain controller, Zivan charger, 120V of Thundersky 160Ah lithium batteries with EVWorks BMS. It has no clutch, has crash inertia switch, circuit breaker with emergency disconnect and fuses as backup. It is a 4 seater but may be a 3 seater depending on weight. It has power steering AND airconditioning. As you can see by the photos the workmanship under the bonnet looks very, very good.

We went for a quick zip around the block and I couldn't believe how much torque it had. Unlike the Curtiss controllers it was quieter than a church mouse, when we got out of the car Connor said it was just soooo cool and can't wait to get the X7 on the road. Seeing this car has given us that extra boost and confidence in what we are trying to achieve. When Steve started the project he approached me to sling a few ideas around but really I learnt way more off him as he has done some thorough research via talking to people who have real experience in converting an EV and indepth internet searches. It was through our discussions that I decided to go for the Logisystems controller, Iota DC/DC converter, Zivan battery charger, opting for an aluminium batt box in the front and he put me on to Google Sketch which has been handy. Thanks for your help Steve and I hope the car does well for you. It certainly looks good!

Front Battery Box

2009-09-12T18:59:00.001+10:00

I've done a lot of procastination for the front battery box. A lot has to do with the price of batteries, initially I want 160Ah Thunderskys at 144V to give good top speed and distance. As I've changed jobs money is a bit tighter than it used to be so I've been looking at alternatives. There are now 90Ah, 100Ah, and 120Ah to choose from either Thundersky or Sky Energy. Packaging is similar in size and I've compromised from my original 160Ah to go for the 120Ah from Sky. The height of the batteries is the same as the 160Ah but have the same footprint as the 90Ah also they are 3.4V as opposed to 3.2V. This should give me a range of 80-100km with a top speed of 120km+.

Now I can organise my front battery box to suit. I'll have 12 batteries in one long string. The box cost me AUS$250 to get made and I'm now working out suitable mounting. I'll use the existing mounts at the front where the radiator was and look at mounting through the chassis rails, to do this I'll need to drill a hole then sleeve it so when the bolt is tightened up it doesn't deform the rail.

New Controller

2009-08-22T19:44:00.000+10:00

I've just got the controller from Cloud Electric in the USA. It is a Logisystems 144V 750Amp. I've recently heard that Logisystems have teamed up with Netgain Motors and the new controllers are red in colour, same as the motors.

One thing to watch out for is the throttle pot as the standard ones don't have a fine enough control at low speed so the motor would be jerky. The new logisystems controllers come with the proper pot as part of the price. Here's some photos when I unpacked it and then when I fixed the cooling fans to it.

Car Show

2009-08-22T18:52:00.000+10:00

Again I've had to put the project aside for awhile for personal matters. However I did go to the car show at the local PCYC and they did have some beautiful vehicles there. You just can't go past the Mustangs and Corvettes and I fell in love with the T-Bucket hot rods. I reckon a bucket would be a beaut EV, look at the room at the back for batteries! (Do I have a blue theme?)

I couldn't get the X7 there so was very disapointed. Definitely next year. There was the Suzuki hatch from Suzi Autos that I saw at a previous show.

Plug Arrangement - finished

2009-06-16T21:27:00.001+10:00

A quick post.

Just finished off the plug recepticle, covered the hole where the petrol filler used to be. Quite neat with plenty of room.

Plug arrangement

2009-06-13T21:31:00.000+10:00

This is NOT the inlet (left)! I've been mulling over the plug arrangement for some time now. A lot of EV's use a caravan type plug/socket, similar to the one to the left. In fact I bought this one for the job. This inlet has an IP32 rating for weather protection, it's not waterproof but the socket is angled downwards to let water run off it instead of into it. This is why it must be fitted vertically. Unfortunately the area at the back of the petrol fill recess doesn't have a flat surface and there's not much room.

To add to things I need a 15amp inlet due to the traction pack (160Ah needs a bigger charger hence 15A instead of 10A). I reckon I've found an elegant solution to my dilemma.

This is what I found at Jaycar's, it has a 16A rating, compact and solidly connected. It even has a locking tab so the plug cannot fall out of the socket. The Jaycar catalogue numbers are:
IEC panel mount male plug 16A - Cat PP-4182 ($6.95)
IEC locking mains lead (2mtr) 16A - Cat No PS-4180 ($22.95)
or if you need 10A
IEC panel mount male plug 10A - Cat No PP-4174 ($4.95)
IEC locking mains lead (2mtr) 10A - Cat No PS-4170 (16.95)

The plug/lead is 2 meters long, I will chop off the 3 pin plug and fit a new one that has a watertight rating, this I will plug into a long extension lead that has a watertight socket.

Looking at the photo on the left you can see that it is angled downwards and fully recessed there is no way water can ingress unless you hit it with a hose! If it wasn't for the lead I could shut the flap, if I could notch the flap without damaging the paint I would have the flap shut while charging. I know, what about the limit switch for the flap to show that it is charging? I am looking at having a relay powered by the plug that will lock out the 'start' circuit. Next I have to fit a plate to cover the holes where the old petrol filler used to be.

Greenfest

2009-06-07T22:38:00.000+10:00

Last weekend Brisbane had 'Greenfest' a three day festival. All sorts of environmental and energy friendly stuff but due to other commitments I could only pop into Greenfest for about half an hour. Saw the only TESLA in Australia which sure looks good (in that untouchable drooling sort of way!).

Also had a look at a 1994 Suzuki hatch that was put together by SuziAuto from Springwood (Brisbane, Queensland). They have on offer to the public converted Suzuki's for a reasonable price (considering for a pro shop), they'll even convert your own car just have a yak to them and discuss what you've got. They're passionate about Suzi's (converted or not) and are friendly sort of blokes. I reckon it's great to see somebody doing something about offering EV's to the public now with a real product instead of just talking about it. Good on ya blokes (and blokessess too), now where is that government assistance?

Thought I'd take another photo as the X7 is now, I do love the wheels. Has a front windscreen now but yet to install the surround (nothing to do about conversions just RX7 restoration stuff).

Change web address

2009-06-07T22:22:00.000+10:00

I'm changing the address to www.electric-rx7.blogspot.com as this will make it easier for people interested in EV conversions to find.

Sorry for any inconvenience!

Brett

Carpets

2009-05-09T17:39:00.000+10:00

Managed to purchase front and back carpets in good condition today.... and at a great price. Thanks Lenny and it was good talking to you.
It's a bit hard to see in the photo but the wife noticed that the handbrake is on the left hand side of the tranny tunnel. Was this originally a left hand drive or is that normal for all RX7's? Will have to check that out.
I'd like to say a big hi to Tosh as he's been following this blog from the start ..... I will finish it one day Tosh!

Motor Mount

2009-04-28T18:54:00.000+10:00

I've had a few days between changing jobs and I've finally got the motor mounting plate welded and fixed to the rubber mounts. Feels pretty strong, maybe a bit overkill but I like it.

I've put a little gusset to add strength to the tabs. For the future I can attach stuff to the plate such as a rev sensor that I can use as an over rev limiter.

New Tyres

2009-04-24T17:18:00.000+10:00

I am a happy man. I've gone to reknown tyre franchises looking for new tyres - 185/70R13's to be exact. They tell me you can't get them as they are not made any more so I was going to go for 205's which mean a wider tyre so more rolling resistance. I took one more shot and went to a small tyre shop and they had them as they sell ALL tyre brands, the other shops only sell THEIR brands. At $89 per tyre fitted and balanced I was very pleased. I also managed to find wheel bolts that where longer to suit the mags. So $356 (tyres) + $56 (bolts) + $100 (mags) = $512 all up, very nice!

Conversion or Restoration?

2009-04-06T20:56:00.000+10:00

Okay, I've been back into the X7 again and it's driving me crazy!!! The conversion is relatively easy but the restoration side of things is an absolute pain in the butt. It takes so much time to source gear and even more ensuring it is the correct bit that will fit. Anybody doing a conversion ....... my advice is to find a car that has all it's pieces AND basic stuff like brakes etc in full working order. Don't get me wrong, this is going to be a great sexy looking and performing car but the restoring is tough. Conversion is a cinch!

I've posted a few photos of installing the motor/gearbox in to the engine bay. Went very, very easy with just my youngest son and myself! Using the hoist and a small trolley jack under the gearbox we mounted the unit with no hassles.

I saw on Ebay a set of 4 mags that suit a Series 1 RX7, I believe that they are limited edition for the Series 1. I bought them and they look great (thanks Keven!). I will eventually change out the Mazda logo in the center hub and will look into getting blanks made with with "X7" etched into them as I don't want Mazda on the vehicle but X7. I've had a few probs with tyres, unfortunately I've found that it is extreamely hard to find tyres of the original size (185/70R13) so went for the Ebay rims which fit 205/65R13, no go. Looks like we can get 205/60R13's which will do okay, $95 fitted and balanced each. So all up A$500 which isn't too bad. I now need to find wheel bolts (they don't have studs) to suit the rims.

Next is fitting and welding the adapter plate. That I'll report on that next.

Help - Trailer needed for car show!

2009-04-01T08:44:00.000+10:00

Help!!! ............................
Just around the corner from us is the Police Citizens Youth Club (PCYC) is holding a car show on July 5th at Logan Central. I want to put the X7 in it to promote electric vehicles but I don't think it will be on the road by then. Does anyone have a car trailer for lend in Brisbane??? Here's the poster for the show, I'd really like to have the X7 there.

2009-03-26T09:13:00.000+10:00

It's been awhile since the last post as the family has been busy and I've been slack. I am now back on the mission. We sent the X7 away for a paint job, the wife said green so green is what we got, tree frog green! Our official name for the car is the "X7" but it seems that a pet name has arisen due to the colour - the "Golblin", after the Green Goblin of Spiderman fame. A number plate may reflect this in the future.

I've posted a photo of the X7 arriving back home and a couple sitting in the garage. I actually like the series one bumper arrangement with the black matching the green, I'll try to keep the black when we install the front windscreen surround.

Next we'll look at the brakes as the car being nearly 30 years old and only 108,000kms I suspect that it has spent a great deal of time sitting doing nothing. So we'll pull the wheel hubs apart and check the bearings and brakes, replace if need be. I've already discovered that the brake master cylinder is siezed and will need to source another one.

Trial run - motor in

2008-12-10T20:09:00.000+10:00

Okay, so we put the motor -adapterplate-gearbox in the X7, coupled up the driveshaft to the diff. We will now take measurements for the motor mounting bracket in the front.

However, we got to thinking ... should we connect up a 12v battery and see if the rear wheel turns? It became a family event, I think it was in 4th gear and away she went! The rear left wheel turned (quickly!!!) and yes we got very, very excited!

Looking at the photos there seems like a lot of room but being a sporty sort of car the area is quite narrow height wise. I feel that we'll have a bit of fun later when we try to get the extra batteries in the front. I know that the batts height is ok but there are the batt monitors that attach to the top of them that increase their height.

Another thing, the engine hoist is the bloody bees knees, makes it soooo much easier to drop the motor/gearbox in.

We are coming up to Xmas and New Year so we'll put the project aside and make room for family time but come end of January we'll be back in to it again.

I'd like to thank everybody for the comments they have been leaving. I'm not up to protocol and if I'm supposed to reply in the comments section please tell me as I'm a bit of a dunce when it comes to computer savvy. The comments have actually helped in encouraging the project. Thanks!

The Green Machine

2008-12-05T17:45:00.001+10:00

When we started this project the family discussed what colour the X7 was going to be. Well, the boys wanted orange with black roof ("Too fast, too furious" ring a bell?) but the boss (wife) came up with apple green (she is either a greenie or likes Kermit the frog ... I suspect the frog) so apple green it is (the boys will get over it ... one day). I have these photos from a while back when I was searching the web so this is what it will look like.

I'm trying to keep it pretty much original but looking at the photos, the larger mag wheels do look good. So, I've done some calculations courtesy of the web and using low profile tyres I can go from 13" to 15" wheels without changing the 13" wheel specs. So we will go with 15" wheels.

Adapter Plate

2008-12-05T16:24:00.000+10:00

It's been over a month now since our last blog. We finally have the adapter plate made.

Went and saw a few local engineering firms but everybody was too busy for a small project like mine, I also wanted a small engineering workshop who would be interested in the project, somebody who cares. I was put on to Fastweld Engineering, I believe they are used to fabricating weird one off jobs. They quickly understood what I wanted.

It took a few weeks to manufacture as it was done in between priority jobs. We discussed if it should be made out of steel or aluminium. Steel is easier and cheaper to get but would take longer to mill, aluminium is a bit dearer but lighter and quicker to mill (which means less labour). We went for aluminium.

As you can see by the photos they have done an exceptional job. I was going to have the edges squared off but they have ground it to match the gearbox. Also the openings for the clutch and starter motor have been closed off with inspection plates, handy.

I think I need to go back a couple of weeks to show how the coupling and the plate looked. The coupling I got from Blackwoods and is in 2 pieces, each having a taper lock. I only use one taperlock onto the motor shaft (the rear half) as I can access it from the front when I unbolt the front half, the other I don't use but have had the center turned down and the spline part of a clutch welded into it. The whole process is all about centering everything, anything that is out of wack will show up later down the track as you put all the parts together. All the bloggs and articles I've read keep stressing the need for minimum tolerances when going for a clutchless setup. If we don't get this right I suspect that the spline on the gearbox will go west first. The coupling that I'm using will probably do the job but if I was to do another conversion I may look at other products.

This is a photo of the plate half done and fitted to the gearbox, nice work aye!!

The guys at Fastweld have done a great job and are really easy to work with. Thanks Dave and Chris!

Rear Battery Box

2008-10-15T13:39:00.000+10:00

The traction battery pack for the X7 will be LFE 160Ah at 144 volts made in China by Thundersky. As I will be going for 144V and each battery is 3.2V then I will have 45 batteries. Now I cannot fit them all in one place so I will split the pack into three. One of 27 batteries in the rear and two of 9 batteries in the front either side of the motor. To reduce weight I've had the rear battery box made of aluminium so to ensure that my batteries will be safe I've had the box made by local industries and not try to do this myself (that would be a very bad thing).

Not knowing who to see as I am relatively new to Brisbane I looked in the yellow pages and approached Alfab for the job but they said that they do mainly boat windscreens and windows but they could do the welding and suggested Lewden Sheetmetal to cut and fold the box.
So I saw Tony at Lewden Sheetmetal and he said he could do it by cutting the sides but folding the box along the long edges to maintain strength. Which he did very well even keeping to a tight set of diamensions.

Then it was back to Alfab where I spoke to Clyde where the welding was done. I don't know the name of the guy who did the welding but he did a nice job. I decided to put in gussets at the corners which will increase torsional strength, you can see these in the top photo. Eventually I'll have a lid made of plexiglass so the batteries can be shown and carpet over top of the plexiglass for normal commute.

As you can see in this photo the box will have plenty of clearance. You can just see where the body is cut away for an exhaust.

I've promised both Tony and Clyde that when the project is finished I would bring the X7 over to show them. Thanks for your good work guys.

The motor has arrived

2008-10-13T17:10:00.000+10:00

The motor has arrived! I was at work and had to wait a few days to get home before I could see it. The family was pretty good and they didn't open the package while I was away. When we did open it (within 2 minutes of me getting home) we were pretty well impressed that the physical size is quite a lot smaller than an internal combustion engine (ICE).

I suppose I should give some specs.

Netgain Motors Inc
WarP 9 motor
Series DC motor
Weight -- 70kg
Length -- 508mm including shafts (Body is 405mm)
Diameter -- 235mm (9.25")
Class H insulation
5500RPM
70HP @ 120 volt 435 amps

This motor is purpose built for electric vehicles (EV's) and has:
Larger commutator than normal
Larger brushes and heavier duty brushgear
Heavier guage wire for windings

Why is it called WarP 9? The '9' is for 9 1/2" diameter. To explain the 'WarP' here's an excerp from the owner's manual:
"We are not 'Trekkies', but we do enjoy Startrek. However, that had nothing to do with the original name selection for our motors. The name was a natural way of differentiating our motor series, and also showed that we intended on incorporating new and advanced thinking in the enhanced design of the motors we planned on building. The War portion of the name comes from Warfield Electric Motor Company. Jerry Warfield was instrumental in our original designs (and subsequent designs, as were John Wayland and numerous others ...). The capital P at the end of the name is also significant. It stands for Phil Brown, a close friend and supporter of our original electric dragster concept vehicle. Unfortunately, Phil was taken by cancer prior to the project gaining momentum. We intend to maintain this method of honoring Phil in the naming of our ImPulse motors as well."

Having been an electrician for over 30 years predominantly in heavy industry I've been exposed to a lot of motors both AC and DC from the tiddlers to having headaches with 2.1MW motors. On first inspection I would say the WarP 9 is of good manufacture and should last many years with proper maintenance (which is minimal).

At present we are taking measurements for the adapter plate but first we are sorting out the coupling between the gearbox and motor. Hopefully we should have this resolved in the next week where we will post our results. Also the rear battery box is being finished, we are putting a few gussets in to increase the strength at the top - not needed but I've opted for extra strength, again we'll post some info on the completed box. Things are starting to come together and once the adapter plate is done, then comes the paint job for the body, then it's time to piece everything together to make a viable vehicle. Bear in mind that this is a restoration as well as an EV conversion but I am looking at a finish date about Easter?

In Startrek they would travel at warp factor 4+ ... I've never had a speeding ticket but can the X7 do warp 9? How fast is warp 1?

Cutting for the rear battery box

2008-09-17T20:38:00.000+10:00

I've been racking my brain and trying to set a program outlining the step by step progression for converting however I keep changing my mind and if I stop long enough I change it again. I came back from work determined to get the body painted before Christmas but ... dammit, I've changed it again! I've realised that as it is new to me and that there aren't many RX7 conversions I find that I'm working it out as I go, I'm sure that is what everybody else is doing.

So, I will cut the rear boot to accommodate the rear battery box, make up the coupling to connect motor to gearbox, get fabricated the adapter plate, fabricate the front battery boxes and plan the next step after that. Sounds easy doesn't it? So I started on cutting out the rear of the boot for the battery box. They say you should measure twice and cut once ... hell's teeth! I spent 3 hours procrastinating with my measurements before I put my heart in my mouth and made a cut! Of course once I made a start, cutting was 'in like Flynn'. I should mention now that if one is to cut the body of a car I suggest the use of an air saw, it is like a hot knife through butter ... so long as it is only 1-1.5 mm. I bought one from Trade Tools Direct for $68 and I love it! Sometimes I need to use the 4" grinder but the air saw is a beauty.

The problem with the series 1 (S1) RX7 is that the boot is not very big, the spare tyre is recessed with the 50ltr fuel tank underneath that. Together they measure on the vertical 300mm. The batteries are 285mm but I'll need a little extra to accommodate BMS sensors and cables/straps so I am looking at 300mm. So how was I going to get this right? Due to the catch for the hatch is on an angle it made the the fitting of the box awkward so I followed what Ian from ZEVA did and made a box from MDF to the actual dimensions. This allowed me to see if it could fit in, not so much in the hole that I cut out but getting it through the hatch and body of the vehicle.

Looking at the underside of the chassis I have not touched the main chassis rail at all, only the skin at the back section as I want to retain the integral strength of the monochoque body. I've had to make the opening a bit bigger to allow the box to rotate in. I was a bit desperate as I wanted to have 27 batteries in the box with a further 18 batteries in the front, total 45; so reducing the amount of batteries in the rear would completely stuff up my traction voltage. As you can see the picture to the left it will keep the back boot nice and clean. The other picture below shows that it doesn't extend far at all, I made a botch up when I made the mock up as it extends 12mm more than it should. Should the box be too low (but I think the height is okay) I can raise the box within the rear compartment. I originally thought I would weld plate and box onto chassis but now will bolt the box as it is larger than I thought and will have strong tensile strength. One issue that I will be looking at further down the track is that of spare tyre. There is a trend that vehicles are not supplying a spare tyre ie: Lotus Elise, BMW M Roadster, Peugeot 206CC but supply a pressurised can of latex or similar to blow up the flat tyre. A pressurised can of sealant is my preferred course.

The other option is to put a 'skinny' spare on top of the battery box complete with a tie down or even a skinny with flat tyre. Really, how many series 1 have you seen with 15-17" wheels, do they have a spare? Because a 15-17" won't fit in the 13" spare wheel well.

Trial run gearbox & tools

2008-09-17T19:52:00.000+10:00

Things have been quiet in the EV front but now we are making progress. Just got notification that the motor has arrived in Oz, I've paid for it and am waiting for customs then delivery. I've also ordered a bit of gear while I was at it; 12V vacuum pump, contactors, crimpers.

The other day we installed the gearbox and driveshaft to check for fit, I had to source a mounting bracket for the gearbox. It's the little bits and pieces that are going to cost abit as they add up, normally you would have all those parts but I got a rolling shell with some stuff missing ... so I'm finding out.

One of the really great things in doing a conversion is the tools that you get to use and buy if you don't have them! I have a lot of tools but I need them for work so I've had to buy more in for the home workshop. I'm keeping an A4 book to log all the tools bought and conversion parts sourced so at the end I can say "we'll ... that was the most expensive conversion ever". Anyway, tools are not a waste as I use them and if Damo gets an apprenticeship then no doubt there will be a spot of pillaging going on. Check out the new hoist I got from Supercheap Auto, it's a 1250kg job and since it was the last one I got it for $190 which I think is good as I saw a 1000kg model the same at a reputable tool shop for over $300 ... about time I got a deal.

Sidekicks

2008-08-23T21:42:00.000+10:00

Okay ... I need to identify a couple of hoods that bug us when we are working on the X7. Namely Kaiser and Jeb. Kaiser is the big one, a mix of bulldogs & stuff and is not a bad pigdog (but he was retired early and is a family dog now) and Jeb is the midget, a Tenterfield Terrier. They just love it when we get under the car. I just wish that Kaiser would stop licking me when I'm down. How am I going to fit them in the X7?

A few figures

2008-08-17T19:33:00.000+10:00

When I first looked at converting I was looking at a Ford Courier Xtra-Cab, this is because it has a high GVM rating and has seating for four. The high GVM would allow me to carry 24 6-Volt lead acid batteries with a high ampere-hour (Ah) of 256Ah. 24 batteries would give me a motor voltage of 144 volts (6V x 24 batt = 144V). Unfortunately at 31kg per battery that means 744kg of extra weight, hence the requirement for a high GVM. If I exceed the GVM then I will need to upgrade axles, suspension, brakes etc. In short, becomes a bit of a nightmare so 24 batteries would be max weight for GVM. One problem with lead acid batteries is something called the Peukert factor, this is when the batteries are discharged quickly it reduces its effective capacity. This will be different for different batteries, usually in the order 1.8 PF. So for a bank of batteries that have a capacity of 256Ah, they would have an effective capacity of 256Ah ÷ 1.8PF = 142Ah. But it doesn’t stop there, one shouldn’t discharge the batteries past 80% so now you get 142Ah x 0.8 = 113.6Ah. Now it takes about (rough figure) 120 watts to drive a 1 tonne vehicle 1km, this vehicle will have a GVM of 2.4T. That makes it 120W x 2.4T = 288W/km. If I have 113.6AH x 144V = 16358.4W of usable power at 288W/km then 16358.4W ÷ 288W = 56.8km. Not a hell of a lot of kilometers between charges! Lead acid will last about five years if you look after them. The batteries are about $260ea, so about $6240 for the battery bank.

Looking at the RX7 with its low GVM I wouldn’t get many kms per charge on lead acid as the weight would eat into the amount of batteries I could carry. The other solution would be to go to Lithium Iron Phosphate (LiFePo4 or LFP) batteries. The cheapest on the market available are from Thundersky in China (this is the picture on the left), they have a very bad rep a few years back due to a bad batch but have since improved the manufacturing process and I haven’t heard anything bad since. They come in 3V batteries so I would need 48 of them to get 144V, each battery weighs 5.6kg so 5.6kg x 48 = 268.8kg. A lot less than lead acid and also physically smaller. So how many kilometers per charge can I get?

I’m looking at 160Ah at 144V = 23040W. Again I won’t be discharging no more than 80% so 23040W x 0.8 = 18432W capacity. The good thing with LFP is that the Peukert factor is near 1 so there is no reducing the Ah rating. The GVM is about 1.4T (I’m guessing here and have yet to get a firm figure) so 120W/km x 1.4T = 168W/km. So how many kilometers between charges? 18432W ÷ 168W = 109.7km. The Thunderskys will take at least 2000 charges, so if I was to do 100km/charge I would get 200,000km on the battery banks life of 5.5 years.

So what is the cost of running the vehicle? The Thunderskys are about $239/battery at 48 batteries = $11472 …… yikes! Add to that the cost of electricity, the charger will charge at a rate of about 2000W/hr or 2kw/hr for 5-8 hours … say 8 hours. I don’t have a cheap tariff so my power is $0.14c/kwhr so $0.14 x 2kw x 8 hours = $2.24/charge. Lets extend that over 5.5 years … $2.24 x 364 days x 5.5 years = $4484.48 but we’ll add 20% inflation ($896.90) to that which makes it $5381.38. So total cost for 5.5 years is $5381.38 + $11472 = $16853.38 for 200,000kms. That is a cost of $16853.38 ÷ 200,000km = $0.0843/km … say 8.5 cents\km. Using current fuel prices of $1.40/ltr we have a Mazda 3 which runs at 12 cents/km or $24,000/200,000kms and we also have a Pajero which runs at 21.7 cents/km or $43,400/200,000kms. I think the maths speak for themselves even with a 20% increase, I haven’t even looked at any petrol price hikes which would make the figures even more interesting. It is a big outlay for the batteries but I look at as pre paying for fuel. It will be sooo good to drive past petrol stations with rising prices. Also the price of LFP batteries appear to be reducing, this is one of the reasons I’ll purchase the batteries last. Another saving will be that I will only periodically need to change the oil in the diff and gearbox, there will be no need for regular engine oil changes, filters etc. Did I mention the positive effect on the environment? An electric vehicle will reduce pollution by about 20 tonnes of greenhouse gases per year!

Gearboxes and Clutches?

2008-08-17T09:15:00.000+10:00

With an EV conversion you can go with various configurations. One is whether to go with a gearbox or just leave it out. If you go without then a drive shaft to fit will need to be sourced or made. This will be direct coupled to the motor, Netgain motors have a motor for the job designed with extra bearing and coupling etc. However the motor would need to be a bit bigger as it has to cope with the full range of revs (this is a simplified explanation, you can get more detail in the forums). The diff would also need to be changed to give a ratio to suit the motor. With a gearbox the diff doesn’t need to be changed as this has the correct ratios in conjunction with the diff. Only two gears would be used …….. say 2^nd for 0-70 km/hr and 3^rd or 4^th above that. I’ll find out which gears are best when the vehicle is operational. What I’ll do is check performance against battery amperage used and find what is the most economical and which gives me the ooh factor!

The other configuration option is to clutch or not to clutch. Obviously a clutch will make it easy to change gears but mating the motor to the gearbox needs to be precise. A measurement from the combustion motor in relation to the clutch needs to be accurately made. An adapter plate needs to be made between the gearbox and electric motor.

Or … you can leave the clutch out. Changing the gears will be a lot slower as you have to make sure that the power is taken off the motor to allow it to run down a bit then allow the syncro to mesh. This is what I will be doing as the gearboxes had no clutch when I bought them. I’ll go in to this more when I come to manufacture the adapter plate.

So, I bought two gearboxes for $350. If you look at the photo there is not an oil leak from the left gearbox, my dog decided that he would try to claim the g/box as his own and lifted his leg on it. Hence the mark on the floor ... must have given it an extra squirt. I don’t know how good they are but I’m hoping I’ll get one good one out of the two. One has a short shift throw, not that I need it as I won’t be racing! I’ve found that I don’t have a cross member that couples under the gearbox so I’ll have to source one. I did pick up a drive shaft from a Mazda wrecker for $100. So my setup will be with standard gearbox and drive shaft but no clutch.

I had contacted the president of Seven of Clubs Mazda Club of Queensland, a few weeks ago and asked if any members who had an RX like mine and if I could have a look and take photos. You see, I wasn’t there when the car was stripped down so I have boxes of stuff and I’m not sure where it all goes, some things I have multiple parts that I don’t need. Well the president said he had a 1979 RX7 (series one, mine is a 1980 … same series) and we organized to have a look and photo session. Wow, nice ride! This RX is a nice example and I got many photos but talking to him about the restoration was priceless. Having a person go through a restoration I got so many tips I wish I had it on tape. Anyway I now have a good idea of the order of priorities to see this project through. I have an order for a Netgain Warp 9 motor with ZEVA, they said it is on the next shipment which will arrive in about a month. Once I get it we will proceed in this order: adapter plate, motor mounts, battery boxes, strip out again, paint car, re-install motor and boxes and all fittings, make up panel for controller and charger. That's as far as I've planned.

Start of work

2008-07-27T21:05:00.000+10:00

We put it back in the garage, jacked it up and put it on stands. I let the boys (who are keen as mustard I may say) start playing with the tools and DB removed the back muffler.

Then CB removed some hitch attachments. DB hooked in and removed the exhaust. The boys are just starting to learn to use tools and work out what size sockets are the right size.

The next thing to go is the fuel tank.

First photos

2008-07-27T20:45:00.000+10:00

Today we rolled the X7 (we started calling it the X7 instead of RX7 as it won't have a rotary engine) out of the garage and took several photos. Please note that the paint is only primer ready for a rub down then paint. Also note that the body is in excellent condition with no rust anywhere.

Beginnings

2008-07-26T15:37:00.000+10:00

I've been looking at converting a vehicle to electric for a while now. It takes time to research as there is very little in book form however the internet is a fantastic medium for like minded people. I joined the Australian Electric Vehicle Association (AEVA) and reading their forum it is a must if you're thinking of doing a conversion. Zero Emission Vehicles Australia (ZEVA) based in Western Australia has a good website and they have gear to sell and have recently done a project where they converted a 1990 Mazda MX5, nice job too.

I was originally going to convert a Ford Courier Xtracab using lead acid batteries (about 760kg worth) but then I saw on ebay an RX7 and with some recalculations I’ve opted for the RX7. Of course the kids think it’s the bees knees!

We had a look at it and the body is in excellent condition, it has no rust and has just primer over most of the body. Put a bid in for it and got it for $580 not bad! Hired a truck to transport it home and is now sitting in the garage. It doesn’t have an engine, gearbox, driveshaft, front windscreen and the two front seats; everything else is supposed to be there……….we’ll see. Bought two gearboxes today for $350 should have one good one from the two. Next I’ll be seeking a driveshaft.

To get an idea what I’m doing check out these websites……….

www.kiwiev.com This is a very thorough step by step conversion, worth spending a bit of time to look and watch the videos.

www.evute-nz.blogspot.com I was going to do the same conversion.

www.zeva.com.au I’m going to use his motor, controller and other stuff.

www.aeva.asn.au The forum that I read and am active in.

If you can find the documentary "Who killed the electric car" watch it as it'll blow you away with the blatant conniving of the car and oil industries who don't want electric vehicles.

I'll post some photos when I figure out how to do it.