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Electric Miata/MX5.

Jozzer

100 kW
Joined
Apr 19, 2007
Messages
1,069
Location
Swindon UK
Hi guys,

A lot of you wanted to see the car we put together last year - so here you go! I've been putting off taking pictures till the car was more "finished" - but as it's my daily testbed that day is likely a long way off! So - please excuse all the wires and sensors strapped here and there.
THere is actually surprisingly little to see - I'd have to dissasemble it to get clear pics of much of the work.

So - here is the tatty old MX5 used for the conversion.
100_1436 copy.jpg

Here is the drive system (11" 250v Kostov motor and Soliton1 350v 1000A controller from EVnetics)
THis has been coupled to the gearbox and securely mounted to the chassis (without clutch - just as well - you don't need gears with this much power!).
Lewes-20110918-00046.jpg

There are 4 battery boxes, 1 large one under the parcel shelf in the space originally occupied by the petrol tank, and 3 smaller ones mounted under the bonnet ("hood" for all you yanks). All are built into 3mm alluminium boxes and sealed.
Here's the petrol tank box (holding some 10KW/H) during assembly.
Lewes-20110918-00045.jpg

And here it is with half of the bussbars connected up (already looking a bit neater!)
Lewes-20110919-000491.jpg..
 

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The parcel shelf box has been closed off with an MDF shelf and covered with the original carpet - one of these days I'll take the roof off so I can get pics of it finished up to add here..

The 3 boxes under the "hood" can be seen here firmly mounted around the motor and controller.
Lewes-20120329-00147.jpg

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The untidy balance leads are currently connected to a Methods V4 digital BMS system that is in testing - housed in the small slim ally box. The charge controller can also be seen (white plastic lid and 4 terminals).

Inside the car, I run a Cycle Analyst for day to day data needs, and also have an Arduino logging motor temp, motorside current and a few other things. The controller also puts out some excellent data - but unfortionatly on an ethernet port (which is pretty hard to log unless you fit a PC in the car - not the best choice there!).

So - there you go. A few forum members have been by this way and gotten a scary ride - I'll leave it to them to descibe the performance (most of them look a bit green around the gills when they get out - but that may be my driving:D).

Jozz
 
Woot!!! You are the man Jozzer! My hat's off to you sir!
 
Spacey said:
You are a brave man with all that Lipo 8)

Not that much - I've made/used/raced over a dozen vehicles with Lipo packs bigger than 10KW/h, and not had any problems yet. The main thing is to CHECK ALL PACKS VERY CAREFULLY. I don't mean just give them a discharge and charge - that's not enough. Our testing process is to cycle the packs twice looking for any anomolies (high IR cells or low capacity - 3-5% of packs will show faults here), then put them on the shelf for 6 weeks minimum and repeat (often a cell will have a higher self discharge rate than it's buddies and needs to be weeded out so it can't weaken your whole pack - another 2-3% of packs will be found faulty here).
The bigger the pack, the more careful you must be to have all good cells. So far, not a single pack that has passed this testing process has failed in use (out of perhaps a couple of thousand).

Course, that said, a 300KW vehicle is bound to be a bit dangerous.. :twisted:
 
liveforphysics said:
Woot!!! You are the man Jozzer! My hat's off to you sir!
Thanks Luke - but all very easy - and I knew exactly how it was all going to work out. One of the most boring builds I've done in some ways:D All been done before too (except fot the big Turnigy pack - those DIYelectriccar guys are scared of them still;))
 
Regarding power consumption, I'm getting about 230wh/m absolute best (and god it's hard to stay off the throttle to do that!) and 600+wh/m worst (that's a lot easier to do!). Average after a couple of thousand miles overall average is 400wh/m, though on a smooth journey it's fairly easy to stay below 300wh/m (giving me about 65 miles useable range).
Currently there are 3 seperate chargers, if I plug them all in to seperate sockets I can charge from flat in around 4 hours.

For heating there a couple of 1.5kw ceramic heating elements (taken from $15 AC fan heaters) that replace the original heating matrix. Methods has kindly built me a programmable controller for these - when I finally get around to fitting it I should be able to just set a cab temp and have it automatically PWM byt he required amount. (Thanks also to Luke for helping out with the IGBT's needed for this).

How does it go? Well - lets just say I need fatter wheels and tyres :twisted:
The car rarely comes out of 4th gear - it will wheelspin up to 60mph in 4th. 3rd gear is for making smoke, 5th gear is for driving over 80mph (110mph top speed with current gearing and rev limiter).

Jozz
 
WOW. Just WOW. Niiiice. I'm guessing a little over $5.5K for batteries, and no worries about fires. 8) 8) 8) 8) 8)
 
Lol, Jeremy Clakson doesn't deserve the pleasure tbh :lol: He'd pretend the battery went flat after the first lap and have someone pretend to push it back to the garage..
 
Jozzer said:
Lol, Jeremy Clakson doesn't deserve the pleasure tbh :lol: He'd pretend the battery went flat after the first lap and have someone pretend to push it back to the garage..

Yeah but he'd be blown away by the ~500 hp :D

If it would be a drag race against a stock MX-5, the 100m rolling burnout will look very nice on TV :mrgreen:
 
Lol, yeah, a stock car wouldn't have much chance. I took a guy for a ride a few weeks back who had crammed a 4.5l V8 into a Miata - he had spent more money on his and said if he had known what it would be like he would have gone electric instead.
I can get close to 1000A battery side with pack sagging to about 280v on a warm day, so "only" 280KW in. Probably peaking at 300hp to the tyres at best.

EVnetics now make a 1.2MW version of this controller (Called "Shiva, The Destroyer!"). Unfortionatly it won't fit on such a small car - it's a masssive beast! http://www.evnetics.com/products.php?prod=shiva

Jozz
 
Awesome work Steve!! I remember seeing the car last time we came down all empty and waiting for the good stuff!! looking forward to having a go in it! ha ha :mrgreen: will have to come down and see you soon, perhaps another spring/summer EV meet? that is if we can get to the petrol pumps 8)
 
Yup, Busbars are gold bullets carefully soldered in place.

Paul, come down anytime! Fortionatly I don't need the petrol station to have fun. You can gas up the bike for a ride down south in the sunshine surely? Get Deecanio out for a day too - poor guys, up to yer necks in babies!

Jozz
 
Great job.
1200amp blasts must be something.
Do you have a final total weight/corner weights?

I have dreamed of Miata conversion for some time.
I had a 1993 L.E. limited slip, lowered w/bilstiens all around, 5spd & so light.
I beat that car hard for two years even in the snow(up to 4",before it got hung up)
It is my benchmark car still.
That Colin Chapman fella was really on to something with the lightweight stuff.
With a small'ish Lipo pack I bet you can improve the weight & balance of the car.
Make a great autocross car.

Enjoy
:mrgreen:
 
Jozzer said:
Yup, Busbars are gold bullets carefully soldered in place.

Paul, come down anytime! Fortionatly I don't need the petrol station to have fun. You can gas up the bike for a ride down south in the sunshine surely? Get Deecanio out for a day too - poor guys, up to yer necks in babies!

Jozz

Will do Steve! the missus will always give me time out and the bike does need the run!! its sat idle all winter, Ill check with Deec see how he is fixed, be great to see some video of the car in action :D I am not a massive fan of cars but electric ones are different :)
 
We can always take the roof off Paul, so it feels more like a bike;)

I'm getting a lot of requests for visit/testdrives - just to say, if anyone wants to come check it out it's always here juiced up and ready to rip - just give me some notice before showing up.

Cheers,

Steve
 
I can testify to the beastly, stomach re-locating power, that is the Jozztek MX5!

My casual drive is a pedestrian Nissan, so stepping in this car really blew my breath away. Having just come from a track day in an Audi R8 and a caterham 7 they both pale into comparison. Electric FTMFW.

On a wet day the only limitations were tyres and a road length! (and balls on the throttle....haha)

When are you getting it on the track??
 
Wheelspin to 60mph..... Videos or it didn't happen! 8)
 
Jozzer said:
We can always take the roof off Paul, so it feels more like a bike;)

I'm getting a lot of requests for visit/testdrives - just to say, if anyone wants to come check it out it's always here juiced up and ready to rip - just give me some notice before showing up.

Cheers,

Steve

Hi Steve...yes will give you plenty of warning that I am coming down and I reckon we can get a bit of video of the wheel spin if i can hold on the camera as well as the seatbelt!! ha ha
 
Sweeeeeet! :twisted:
 
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