CZal's Mazda Roadster (MX-5)

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Post by CZal » Sun, 06 Jun 2010, 23:05

OK,

Been 'umming and ahing' for a little while now about DC vs AC and the like and finally I've come to a decision.

The first EV should be as simple as possible so I've decided to get a motor mount kit for the Roadster from www.ev-propulsion.com. This will provide the motor <-> gearbox and Motor <-> engine mounts interfaces. And more importantly it will provide the front kit for the A/Con and Power Steering.

My desire to source locally has been saved by EVWorks.com.au who'll be providing the WarP9 and Ian's Aussie built controller...

This will at least get the project moving again and I look forward to all the challenges ahead with fitting the motor and adding in the support circuitry.

Most of all I'm looking forward to the battery placement scenario (I've been reading up on how to remove the MX-5 fuel tank... that looks easy, not!)

Anyway, this means that I have a 22kw 180L sized ACIM free for my second EV!! I think a motor like that will have to go into a Jeep (so the load carrying capacity will be such that it can carry all the batteries needed to drive it to its potential) or if I want to get really sporty, a skyline (big motor and a useless back seat for batteries!!)

Order for the motor/controller went in to EVWorks just now and the kits will be ordered soon (just watching the aussie dollar for a few days...)

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Post by weber » Sun, 06 Jun 2010, 23:12

I think you are very wise. Sounds good CZal.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

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Post by CZal » Mon, 07 Jun 2010, 03:27

Thanks Weber,

Still very interested in your project and will be keeping a close eye on it...

Tritium James, the 180L will stay idle for a long while now if you want to use it for any testing...

Really looking forward to moving ahead with the project now!! :0)


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Post by CZal » Thu, 24 Jun 2010, 17:44

Got the following, much-anticipated, email from Mike at ev-propulsion (who I must say has been very informative through the purchase):

_________________________________________________________________________
Hi Costa,
I almost forgot to send you this tracking number! Usually takes about 8 days....(and tracking updates are usually a day behind)
I will forward the kit instructions in the next day or two so you can see what is involved (not too much) Thanks again for the purchase, and any questions, I am here....
_________________________________________________________________________

This is for a motor mount/gearbox adapter kit and a front accessory mount kit and means that in a fortnight I'll have the components ready to fit the motor and ancillory components (pwr steering, a/con compressor and even an alternator if I'm keen enough).... Now the motor just needs to get here :0)
Last edited by CZal on Thu, 24 Jun 2010, 07:47, edited 1 time in total.

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Post by Nutz » Sat, 31 Jul 2010, 04:10

Hi there zcal, what have you done with the ICE and it's computer, loom etc. Are they for sale?
( don't shoot me......it will help fund an EV :) )
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Post by CZal » Mon, 02 Aug 2010, 17:25

Hi there Nutz,

I've actually given the ICE away to a mate.... The loom is still there (together with the computer I'm sure).... I haven't had a chance to trace either of the two back to see where I can remove them.

ECUs are going for between $100-$200 on Ebay but I'm sure we can come to some kind of arrangement using the universal payment method (a slab or some work on the car :) if you can show where they can be removed without affecting the low voltage operation of the vehicale

I'll have a look for the ECU tonight and let you know....

C.


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Post by EV2Go » Mon, 02 Aug 2010, 22:27

So what was the final decision for the motor? Warp 9?

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Post by CZal » Mon, 02 Aug 2010, 22:54

Yep Warp9...

Simplicity was the deciding factor here... After driving Jeff's EV to Brisbane I decided that I would have enough to do without re-engineering motor mounts and the like!!

I've actually been working on the car and snapping pics as I've been going but each time I try to upload them the site tells me the pics aren't JPEGs, even though Windows sees them as such.... Hmmmmm obviously the crackberry pics aren't JPGs?? or when Windows compressed them it changed their format... not sure on that one yet...

I'll try the detailed post tomorrow, with some pics, but basically:

- The soft top is off (it just need to be replaced, nothing to do with the conversion)
- The door trims are off and the electric window guides have been greased (again just plain maintenance)
- The rear parcel shelf trim is off and I can see the top of the petrol tank


Next is:
- Get some new engine mounts for the electric motor mount
- Remove what's left of the exhaust
- Drop the tailshaft and gearbox to remove the petrol tank


Last edited by CZal on Mon, 02 Aug 2010, 20:17, edited 1 time in total.

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Post by Nutz » Tue, 03 Aug 2010, 00:46

ecu is commonly kept in the kick panel next to the passenger's feet.
Where in Melbourne are you? I would love to get involved if I can.(I am in Lilydale)
Troy
I still hope to convert my own car one day, it would be good to see just what i would be getting into.
Last edited by Nutz on Mon, 02 Aug 2010, 14:54, edited 1 time in total.
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Post by CZal » Tue, 03 Aug 2010, 06:15

Didn't get a chance to remove the kick panel after getting home from work today, but since we never removed it when taking out the IC, I'll have to assume it's still there...

Happy for any help as everyday work keeps getting in the way (going through re-structure at the mo...) and happy to give advice (first piece of advice, start with a bigger car than an MX-5! hey Weber :0)

Now that I've been into it a little while, I think a Ute is a perfect conversion, closely followed by a 2+2 coupe (for the sporty amongst us) that you can turn into a 2 seater with the +2backseat having space and weight allocation for batteries or controller... Skylines are coming into the right price point now

I'm in Chaddy, just near the shopping centre.. Drop me an email any time, costa.tzalis@bupa.com.au


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Post by weber » Tue, 03 Aug 2010, 06:26

CZal wrote: Happy for any help as everyday work keeps getting in the way (going through re-structure at the mo...) and happy to give advice (first piece of advice, start with a bigger car than an MX-5! hey Weber :0)

Hi Czal,
Bigger car? Nah. Gotta have a challenge. :) Good to hear yours is coming along. Onya mate!
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Post by CZal » Tue, 03 Aug 2010, 23:43

Thanks Weber,

Still keeping an eye on yours....

I've had the WarP9 land today as well (Thanks a lot to Ian from EVWorks)

Image

(Finally found that if I converted image to gif, it would then upload... Anyone else having probs uploading JPGs? (I've tried JPGs from my crackberry as well as my workmate's iPhone)

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Post by Johny » Tue, 03 Aug 2010, 23:48

You probably already know but I think that jpgs have to be < 100KB size.

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Post by CZal » Tue, 03 Aug 2010, 23:52

Now that uploading is going and I'm in posting mode, here's some pics of the kit that came from EVPropulsion:

Image
This is the set. It contains the gearbox adapter, motor mount and the front mount for the aircon and pwr steering

Image
This is just me being artistic :0)

Not in the photos is the shaft coupler and a bag of bits and bolts.

Initial view of the quality of the workmanship looks good, more as I get a chance to put it together....

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Post by CZal » Tue, 03 Aug 2010, 23:57

Hi Johnny,

yep JPGs have to be <100kb...

The initial photos are over, so i've been trying to compress them using WinXP Office Picture Manager. Not over by much mind you, approx 130kb!

I've taken photos using my crackberry and today using my workmate's iPhone. They then get compressed using the PicMgr. I even tried exporting them to compressed JPG to make sure the format wasn't being changed when compressing. That's when I thought I'd try exporting to .gif

Oh well.... .gif will have to do..... :0)

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Post by CZal » Wed, 04 Aug 2010, 00:32

DC-DC:

OK I've got options here for DC-DC conversion:

1. Commercial adapater
       Expensive, no design fun :)
2. PC Pwr Supply
       Cheap (I've got an EPS pwr supply from an old Xeon workstation I built)
       Problems with stuff jarring free in a difficult environment
3. Use the alternator
       Lol.... I know this might initially sound dumb but it's actually the only re-gen I'll get in a DC system.
       Would've done it too except most alternators will self excite and then remain a drag on the motor
       If I could control when the draw was active I would've implemented it just to see how it ran
4. Just use a LiFePo4 battery and charge it when chargin traction pack
       Still my favourite option, I can't imagine the Acc battery running out before the traction does.


Finally I managed to score 4 of these from work last week.



      ImageImage
(Sorry about res, camera phone, exporting to compressed gif)

They were incorrectly shipped to us and are 72V-12V DC converters for some Cisco switches we have. (basically you can run your switches off DC if you lose AC power)

I actually really like them as they are beautifully built. Everything is very sturdy and glued down... Additionally all the heatsinks push up against the top cover, so there is really very little chance that anything will move in them, even if mounted on their side.

I'm thinking I can bias up the output to 13.8V.   I'm going to have a 144v pack so the general plan would be to have two of them in parallel, each running across half the traction pack. Of course this begs two questions:

1. Does having them in parallel cause any concern about the output of one blowing up the other?
2. Am I just opening up myself to an unbalanced pack?

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Post by CZal » Wed, 04 Aug 2010, 00:54

Actually I missed one more option for DC-DC that really interests me (especially if I need to have DC-DC for compliance reasons).

Generally speaking I'll be driving this car during the day, the actual drain on the accessory battery is generally very low during the day when the headlights aren't on. Obviously there are peaks (braking while indicator is on, when windscreen wipers are going, when aircon is running, stereo blaring :) But this doesn't actually happen too often.

I really like the idea of Sealed Laptop power packs as they're really well enclosed and rugged. I have one such device that provides 18V@6A. My general theory goes like this:

- Drop 18V to 13.8V (using some diodes)
- Have the power pack provide Acc power when draw is <6A
      - When draw is less than 6A, pwr pack charges Acc battery
- Have the battery provide additional power when draw is >6A

Not sure if this theory holds up? (I know this has been discussed previously in one of the forums but for the life of me I can't find it again... anyone got a link?)

Obviously just having a decent LiFePo4 Acc Battery that gets charged when the traction pack is charged is much easier.....


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Post by antiscab » Wed, 04 Aug 2010, 01:59

CZal wrote: I really like the idea of Sealed Laptop power packs as they're really well enclosed and rugged. I have one such device that provides 18V@6A. My general theory goes like this:

- Drop 18V to 13.8V (using some diodes)


some laptop powersupplies limit current effectively.

try running the output of the supply at 13.8v before playing with diodes.

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Post by coulomb » Wed, 04 Aug 2010, 02:39

CZal wrote: I really like the idea of Sealed Laptop power packs as they're really well enclosed and rugged. I have one such device that provides 18V@6A.
So this is an AC to DC power supply designed for 110 VAC perhaps, and you are feeding it with 144 V nominal? That sounds doable.
My general theory goes like this:

- Drop 18V to 13.8V (using some diodes)
Eew. I'd really try and avoid the dropping of 4.2 V @ up to 6 A. That's up over 25 W peak. Plus, it's turning a little pack energy into heat. I know it's an insignificant amount in the scheme of things, but it just doesn't feel right to me.
- Have the power pack provide Acc power when draw is <6A
      - When draw is less than 6A, pwr pack charges Acc battery
- Have the battery provide additional power when draw is >6A
This will happen automatically if you just put a 13.8 V power supply across the battery and run everything off the battery, as long as the power supply limits current gracefully. Some power supplies do; most switching power supplies don't. Instead, they turn themselves off to avoid the overload, try again some seconds later, and you get this "hiccup" action which stops the power supply from overheating, but doesn't deliver much power at all.
Obviously just having a decent LiFePo4 Acc Battery that gets charged when the traction pack is charged is much easier....

I think that lead acid (probably a sealed one) is still more suitable for the accessory battery. Maybe one day that will change, but by that time people might be starting their cars and trucks with LiFePO4 batteries.
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Post by coulomb » Wed, 04 Aug 2010, 02:47

CZal wrote: 1. Does having them in parallel cause any concern about the output of one blowing up the other?
Some people advocate a diode in series with each power supply's output. Personally, I don't see how it helps much; the back end of each power supply is probably already a fast bridge rectifier. However, the diodes would help some with load sharing.
2. Am I just opening up myself to an unbalanced pack?

The consensus seems to be that the unbalance is tolerable as long as the two power supplies share the load close to equally. This is the same problem that many high voltage AC conversions face (our MX-5 included). We intend to use some long leads as equalising resistors, and use the voltage and current adjusting pots on our power supplies to achieve a good balance. Our BMS will presumably take care of the inevitable slight imbalance that will will still be there.

We discuss our power supplies and current sharing in DC/DC selection and LED power supplies arrive.

Edit: "each output" -> "each power supply's output".
Edit: also possibly of interest: Jaycar power supply as charger?. In particular, PowerBox is an Australian company that makes power supplies, some of which are suitably current limited.
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Post by CZal » Wed, 04 Aug 2010, 16:16

Thanks for the responses all,

I'll pull the laptop pwr supply apart when I get a chance and see if I can bias the output down internally and if I can I'll also see if I can draw more than 6A from the supply and see how it responds (limits or turns off or even blows magic white smoke) If it doesn't limit then even just charging the Acc battery won't be doable...

Thanks for the reminder coulomb, I knew I'd read about this subject matter somewhere.... It definitely was in your DC/DC section (I was searching on DC-DC and of course didn't find it again...)

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Post by Carv'n Marv'n » Wed, 04 Aug 2010, 16:52

...for some reason, a .jpg file will not upload, but if it's a .JPG it will. Case sensitive.
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Post by CZal » Sat, 09 Oct 2010, 04:10

I can't believe it's been two months since I last posted. Time goes past so quickly... :0(

Since the last post, I've managed to engage a consulting VASS Engineer (thanks Daryl from the AEVA meetings). His name is Askar and he put me in touch with John Adriaanse who'll be helping with the battery box build and installation.

Basically any 'easy' changes (removal of the exhaust/folding roof etc) have been completed and now it's time to do the bits that need to be engineered.

This is a nice segway into the next big purchase, batteries




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Post by CZal » Sat, 09 Oct 2010, 05:32

OK with the Aussie dollar so strong, it seems a perfect time to make the next big investment... Batteries

I've already decided on LiFePo4s and most likely Thundersky...

I'll be having a 144V pack so that means 45 cells at 3.2V each. The big question is the amount of Ah to get. I'm trying to decide between 60Ah and 90Ah.

They're actually of similar size and I think they'll both provide the 600A max that the controller can handle but there are a few big differences:

a. over $2,000 cost difference
(yep certainly enough of an incentive to try to make the 60s work)

b. 31kg weight difference
Not huge but obviously helps the cause. With a 2:3 front:back split the weight over the rear axle is only 20kg heavier than a full petrol tank (originally 45L) (62kg using the 60s vs 81kg using the 90s, + battery box weight)

c. Range
Obviously better with the 90s... I'm trying to quantify this using the various range calculators on the web. I must say though, I only have a 7km commute to work so range may not be too much of an issue (well maybe not enough to be a $2,000 issue!)

d. Constant discharge (real reason for this post)
Although I only have a 7km commute a big chunk of that is on the freeway so constant discharge is a concern.
TS batteries have a 3C constant discharge rating, which means that the 60s can put out 180A continuously. The controller can put out 200A constantly. I guess the question is how much current do you normally use continuously? I know this depends on the lay of the land and how fast your travelling, but I guess I'm looking to the experience of our members that actually have their EV running...
What would you say your normal discharge experience is?
Do you normally see >180A for extended periods of time?


(Alternatively go for the SkyEnergy 60s which give 4C discharge continuous, just strange that their 'continuous' has a 30second time limit on it)

I'm certain the answer's already in the forums but when you search on 'continuous' or 'constant' the returned options are taking a while to get through... I'll continue to search the forums but direct advice here would be great...


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Post by EV2Go » Sat, 09 Oct 2010, 05:44

From my limited understanding the SE are basically a minor upgrade from the TS batteries, and deliver slightly better performance.

So if the dollars are similiar I would go the SE.

How hard do you want to accelerate? I wouldn't rely too heavily on either batteries doing massively over 3C.

Are you ever likely to want to do longer trips? and would it be over the 60Ah range capacity?

Based on a similar vehicle of a weight, motor and battery pack you can expect the 90Ah to take you about 70klms and the 60Ah to take you about 46klms.
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