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Discussion Starter #1
I decided to start my own thread to not ruin others discussions with my own troubles :)

My name is Miroslav and I'm addicted to electro-mobility :) First I must say that I'm car enthusiast in general, E.V. is not the only world for me. US cars is my passion but since the interesting ones are too heavy for reasonable E.V. conversion, I have decided to go Japanese sport sedan way.

Since RX-8 came to market I loved Lincoln Continental-style suicide doors. I like that engine is placed behind front axle giving the car great driving performance. Unfortunately high-RPM Wankel engine always ruined RX-8 for me. No need to say my experience with electric cars was none, because I even thought about corvette V8 engine conversion.

Some stuff in life happened from back then like school finish, job changes, Microvett Pinguin 6 E.V. purchase and today I work for GWL-Power company as a technician. GWL is very well known LiFePo4 supplier, for those living in Europe at least I guess.


For about four years already I'm collecting experience with electric cars and everything related. Some time ago I crossed The Bolt - Slovenian RX8 conversion. Suddenly Mazda was back in the game for me!

Now I think it is good time to thank DIYelectriccar forum members Mike (Skooler), Spyder e.v., kakheath and tcole6 for inspiration and courage to convert such a wonderful car as Mazda RX-8 is.

Thank you very much for everyone’s input. I hope my built will bring some new experience not just to me, but to everybody involved including you. If I’m incorrect, feel free to share your advice anytime. Also please feel free to Select, Copy and Paste my writings into your replies. Finally please forgive me for ruining English language.
 

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I must say I envy you guys in Great Britain your used cars prices. In Czech Republic even 2003 models are unreasonably expensive. After about one month spent at used cars sales servers, I paid 4000 EUR for 2004 RX-8 with faulty engine in configuration I wanted: 6-speed manual gearbox, not that red leather interior, heated seats for fake feeling of warm and GPS display in dashboard for later use as a Amps, Voltage display. Later I found out that it is very easy to convert not-GPS equipped Mazda to display in dash version.

First good advice I can give to anyone who would like to do the same, it appeared to be very difficult to register car with faulty engine imported from different country. I found my Mazda in Vienna, Austria. Import and registration from EU is not difficult, however with car which is not running it is something different. It is also not possible to convert car to E.V. first and then register it in your country for a first time, E.U. car registration legislation is not ready for such a procedure. Of course if you don’t want to proceed full scale homologation, which is obviously terribly expensive and not needed for single car conversion.

Luckily the guy whom I sold the Wankel engine to borrowed me some parts to make my Mazda ran at fossil fuel one last time.

As you can see, even 4 thousand EUR priced cars are not very beautiful. Technical condition was more important to me then appearance.





As far as today I managed to get rid of unimportant parts. Some of them are quite easy to sell, like engine itself or exhaust. The rest I will have to store for some more time, at least it appears so.







I think it is no point to post many pictures of car without engine and other parts. However I pictured everything before, during and after, have it labeled and sorted. So if anyone wants something specific, please send me a message.
 

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Now what is out of discussion: I'm here for DC conversion. I'm well aware of AC motor benefits. There are two main reasons for my decision. First is the fact that I was unable to find components for high-performance application for price enough so I could afford it. Second reason is simplicity of DC conversion if you have hi-performance application still on your mind. This is it, but please take in advance that my next RX-8 sure will be AC powered! :)



And here it is, Kostov K11 Alpha when it arrived. Warp motor import to Europe is quite expensive because of import duty and shipping cost for heavy item. I also did not managed to find any old forklift truck or industrial DC motor that would fit my needs. Dual motor was also an option, but after some consulting with Mr. Plamen from Kostov I decided to try the Alpha.

Hereby I confirm that RX-7 adaptor from canev.com fits RX-8 six speed gearbox and also to Kostov DC motors. Some of you might think that by purchasing components which you just bolt together is not very innovative or even interesting but I don’t care.

In my previous job I worked for a company which specialized except others also in fitting EURO pollution standard friendly engines into Russian cars and trucks, which does not dispose of such an engine in original. I assisted in development of reduction flanges between engine and gearbox many times and my advice is if you can buy it, do it. You don't notice it immediately, but in long time use any misalignment, vibration, imbalance or other hard to find issue can cause disaster and damage many other parts and cause abnormal wear of component which you would not even expected. It needs to be done very well and development is expensive if you value your time.

This is how far I managed to proceed until now. I also asked guy with carousel (I hope it is the right name for that machine) to modify original RX-8 flywheel for me. Originally it is purposely imbalanced, because they balance it together with Wankel engine crankshaft. Lot of material was taken off, it went from 7.6 to 5 kg!

This weekend I hope to fit motor with gearbox to the car so I could design the motor holders. Kostov K11 Alpha is shorter and should not collide with font axle as far as I measured. It also offers screws in motor body, which means designing the holders should be easy since there is no need to mount the motor only for front or back lid plus belly belt. I will post some pictures as soon as it will be in position.
 

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Discussion Starter #4 (Edited)
Here are some topics for discussions, aka troubles which I will face in near future:

1 - Motor cables and their influence to electromagnetic compatibility. The shorter the better, right? How do you shield them? Do you lead plus and minus wire close next to each other?

2 – Heating. Does somebody have experience with this device? http://www.evworks.com.au/index.php?product=AIR-AC-RCVALVE
As far as I understand it can make car air conditioner to work as a heater in same principle as for example office / hotel air conditioners. It seems to be brilliant idea if I want to keep A/C in the car.

3 – There goes my next question connected with previous one. How powerful electric motor do I need for A/C compressor? Also what RPM should A/C compressor work at? Is there some general experience? From what I experienced I think that Air conditioning in ICE powered car works very well also when standing at place with motor at idle. Therefore I should be able to count RPM for A/C compressor from Wankel motor pulleys diameters and Wankel engine standard idle. Am I thinking about this right? Isn’t there easier way how to find out?

4 – DC-DC converter. Generator at Wankel engine is 100Amps. Does it mean I really need at least 100 Amps DC-DC converter?

It appears to be big problem to find reliable DC-DC. At GWL we have tested some chines converters 72V DC to 13,5V DC and also 144V to 13,5V, but they seems to die pretty fast, even if I connected them through inductor. Right now we are using Meanwell SP350 unit in our test van. SP-350 is AC power source which can work with DC as well without violating warranty of the product. However it seems that at our nominal voltage 144V it cannot power board equipment correctly. It behaves strangely – it is pulsing 13,5V on output in non-regular pulses. This makes me think 144V input is just not enough to power at least headlights, taillights and motor fan.

Since K11 Alpha is designed to work with 250V, this will be my pack voltage. I think this would fix Meanwell DC-DC issues, however I don't quite trust it anymore. So I checked Chennic offer and from what I have read generally there is good experience with them. However their 125A 250V top of the range product is quite expensive.

Any other recommendations?

5 – Controller. I think I will proceed with Soliton 1 since K11 Alpha should handle 1000Amps peak and Soliton 1 is capable of performing that. Anyway I have Soliton Jr. right now at my disposal. So I think I will use it and proceed with smaller version, I will need money for batteries, right :-/

Am I correct that connections and also setup options of Soliton Jr and Soliton 1 are basically identical? So it should not be problem to just switch the controllers when I would decide to go for Soliton 1 later?

6 – Controller shielding. Do you shield your controllers? My experience with Soliton Jr. is that simple grounding is far not enough. Not to just listen FM radio in the car. I can hear increasing and decreasing humming sounds from speakers when pushing accelerator pedal even before motor starts to rotate, so I guess this is controller electromagnetic wave interfering with car stereo. How to prevent this?

Since E.U. legislative is very unclear about registration of E.V. conversions, or at least here in Czech Republic, I want to make sure that I will do everything possible to pass possible EMC test later. I need to think about it during the built already so I was thinking of some cage around controller. Did you solved such issue?
 

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Discussion Starter #5
Today I did not proceeded as far as I wanted to. I managed to wash transmission little bit and replace reverse gear sensor which caused leakage.

I found two weights at the car which I suppose serve against vibrations. One is mounted at the end of gearbox, second - the long one is inside the "spine" which connects gearbox with differential.
I installed them back after taking the picture but I was thinking about not to do so. They are quite heavy and while the vibrations source (ICE) is out, it should not cause any harm.

 

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Those "weights" are Lancaster Dampers
I think you did right to leave them on - because they are located on the diff spine and gearbox there are probably there to eliminate specific vibrations from the diff/gearbox

Would be an interesting experiment to try the finished car with and without them
 

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...
1 - Motor cables and their influence to electromagnetic compatibility. The shorter the better, right? How do you shield them? Do you lead plus and minus wire close next to each other?
I briefly discuss this in the Soliton manual, and have posted about this numerous times on here, but to summarize, the battery cables carry pulsating current so they will radiate magnetic fields. The most effective way to reduce this radiation is to minimize the "loop area" of the circuit. That means placing the battery cables side by side over their entire run (including inside the battery boxes - a detail that is often overlooked). The motor cables carry pulsating voltage so they will mainly radiate electric fields (same as a radio transmitter). To reduce this radiation you want to make the motor cables as short as possible and, optionally, enclose them in a metal conduit that is grounded to the vehicle chassis on both ends (NOT to the traction battery).

Broadband RF noise is also produced by the brushes sparking. This can be reduced/eliminated by placing a small value film capacitor across the *armature* terminals of the motor (NOT across the motor as a whole!). For RFI suppression 0.1uF (100nF) is generally most effective, but anything from 47nF to 1uF will work. Note that a 100nF capacitor might have to carry 1A or more of current at 8kHz depending on the battery pack voltage, so use a physically large capacitor with wide/flat terminals. IGBT "snubber" capacitors are a good choice for this application.

...
3 – There goes my next question connected with previous one. How powerful electric motor do I need for A/C compressor? Also what RPM should A/C compressor work at?
From our tests here, A/C compressors require 1-3kW, depending mainly on the size of the car and the surface area of exposed glass. You'll have to experiment with the idle RPM to see how low you can set it and still get cooling, but 800RPM would be a good starting point.

As for installing a reversing valve to turn the A/C into a heat-pump, I am not an A/C tech, but my understanding is that you have to replace the orifice tube with a bidirectional expansion valve otherwise the efficiency in heating mode will be terrible.

4 – DC-DC converter. Generator at Wankel engine is 100Amps. Does it mean I really need at least 100 Amps DC-DC converter?
Modern cars have a lot of electronics, but you shouldn't need 100A unless the power steering is electric. That alone will draw 40-60A.

As crude/ridiculous as this might sound, if you are going to idle the motor to run the A/C compressor, it might make sense to build a bracket to drive the alternator and any other belt-driven accessories as well. While an alternator is less efficient than a DC/DC converter, it is definitely a lot more reliable. The sad truth is that *none* of the DC/DC converters typically used by DIYers in EVs are worth a crap - they are the least reliable component in most conversions by far, actually.

5 – ...
Am I correct that connections and also setup options of Soliton Jr and Soliton 1 are basically identical? So it should not be problem to just switch the controllers when I would decide to go for Soliton 1 later?
Most of the settings are the same; the exceptions are the obvious ones like motor current, motor power, battery current, etc. The low voltage connections are the same, but different stud sizes are used for the high voltage terminals - 3/8" (10mm) on the Soliton Jr; 1/2" (13mm) on the Soliton 1.


6 – Controller shielding. Do you shield your controllers? My experience with Soliton Jr. is that simple grounding is far not enough. Not to just listen FM radio in the car. I can hear increasing and decreasing humming sounds from speakers when pushing accelerator pedal even before motor starts to rotate, so I guess this is controller electromagnetic wave interfering with car stereo. How to prevent this?
It is rare for our controllers to radiate enough noise to interfere with even an AM radio, much less an FM radio. This type of problem is best solved by installing a noise filter on the power leads to the radio, first. Only if that doesn't work should you attempt more extreme measures (which I already outlined above).
 

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Discussion Starter #9
Thank you for valuable information provided. As for electromagnetic interference I use old long and medium wave radio to hear more, but for test van even FM frequency is disturbed a lot. I will think of some smarter way how to lead motor and pack cables and check what more can I do for improvement. I will also browse the forum more for your other posts related with this issue.

...Modern cars have a lot of electronics, but you shouldn't need 100A unless the power steering is electric. That alone will draw 40-60A.
This is the case for Mazda RX-8. It explains need for a big generator.

it might make sense to build a bracket to drive the alternator and any other belt-driven accessories as well. While an alternator is less efficient than a DC/DC converter, it is definitely a lot more reliable.
This is disadvantage of Kostov K11 Alpha application. There is no option how to fit any bracket with pulley to drive accessories. It relies only at active fan cooling and I can think of no way how to fit a pulley on it.
Some gearboxes has a lid for optional output for driven accessories such as winch, slow plow, etc. This could be used as well but this is not the case of Mazda RX8 6 speed gearbox. I'm afraid I will have to rely on DC-DC.
 

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Discussion Starter #11
There was not much time to continue at Mazda, but my last progress is quite significant step. First we have fitted Kostov motor with canev adaptor, clutch and eventually gearbox. Bolts that came with canev adaptor are too short. I guess RX-7 gearbox flange (for which the adaptor is designed) is little but thinner. Unfortunately original Mazda bolts that holds gearbox together with wankel engine are too short to be used with canev adaptor as well. It is necessary to buy new longer bolts.





Then we have fitted motor already connected with the gearbox to the car. It was hard work, the fitting itself took about two hours. Kostov K11 Alpha weight is 75 kg, so using some kind of crane or lifter is necessary. You can get the idea how we have proceeded from the picture below.





There is not much space left from the steering rack, but at least it was not necessary to change the angle of the gearbox position in the car.



I'm not sure how much I need airflow blowing from the grill in front bumper for cooling the engine. There is very nice place for battery pack in front of steering rack. I hope there will be sufficient air flow going through steering rack from the bottom of the car.

 

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Great job mate. Don’t worry guys ain’t responding in large number. Probably still trying to figure out, where the hell, a Czech could get this kind of money from. They’ll come around. Eventually.

What’s that cute black thing in front of the axle beam doing ? Giving hand? Or just checking if her(his) master didn’t go mad?

Don’t let up mate.

Cheers
Chris
 

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Great pictures! I'm considering the RX-8 as my next project. I am glad you said that the RX-7 adapter from can-ev will fit. Aside from the battery racks, I think the adapter/ coupler job was the worst part of doing my conversion.
 

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Great job mate. Don’t worry guys ain’t responding in large number. Probably still trying to figure out, where the hell, a Czech could get this kind of money from. They’ll come around. Eventually.
In the Czech Republic we call it "high tech & low life", or LiFe is good :)
 

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Hey, if you're looking for a cheap DC-DC converter, see if you can lay hands on one of these babies:
http://www.ebay.com/itm/2000-HONDA-INSIGHT-DC-POWER-CONVERTER-INVERTER-PCU-OEM/390627473221?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D17397%26meid%3D1333436633197238969%26pid%3D100011%26prg%3D8093%26rk%3D1%26rkt%3D5%26sd%3D321179119171%26

They can usually be had around $120-140 US, and in 11 years of the insightcentral.net forum, there's not been a posting about one that failed. Takes ~70V - 220V (cuts out above or below that). Rated for up to 70A I believe.

Here's a link to the necessities to make it work:
http://www.insightcentral.net/forums/modifications-technical-issues/21025-dc-dc-inverter-needed-experiment-2.html#post209599

And to the whole thread:
http://www.insightcentral.net/forums/modifications-technical-issues/21025-dc-dc-inverter-needed-experiment.html
 

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Discussion Starter #17
Great job mate. Don’t worry guys ain’t responding in large number. Probably still trying to figure out, where the hell, a Czech could get this kind of money from. They’ll come around. Eventually.

What’s that cute black thing in front of the axle beam doing ? Giving hand? Or just checking if her(his) master didn’t go mad?

Don’t let up mate.

Cheers
Chris
Thank you Chris, I appreciate it. As my friend Kortas said, it is pretty much hi-tech, low-life style although I would like it to be otherwise. It is basically about how much are you able to give up to reach your dreams ;-) As you can clearly see from the pictures, our conditions and equipment are far from professional workshop.

I can see you have noticed my fathers nameless cat :) Yes, she is a little helper and rich resource of paw print on my cars.
 

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Discussion Starter #18
Great pictures! I'm considering the RX-8 as my next project. I am glad you said that the RX-7 adapter from can-ev will fit. Aside from the battery racks, I think the adapter/ coupler job was the worst part of doing my conversion.
This is why I started the thread. I think RX-8 was designed to become E.V. one day! Even creators were probably not aware of it back then :)
I will be happy if my posts will help anyone to succeed in similar task. I document everything so if anybody needs something specific, just ask!

Yes, RX-7 adapter from CAN-EV will fit 6-speed RX-8 manual gearbox. Bolts included are short however.
 

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Hey, if you're looking for a cheap DC-DC converter, see if you can lay hands on one of these babies:...
Thank you very much Sir! This is good information. I will examine it further and I must first be sure about my current requirements since the power steering is electric. I'm also not sure how much power those xenon headlights needs.



To be honest I postponed DC-DC issue a little bit, trying to use all free time to reach some real progress at the car itself instead. As soon as motor holders will be finished, battery boxes are the next challenge. I'm also not really sure yet where to place the soliton controller. I doubt I will be able to fit it instead of fuel tank as I wish to. I would also like to use the space under the hood for the cells, because with 250V pack voltage I'm affraid I will need a lot of space.. So the spot behind the front grill seems to be good idea for now.
First things first, so I think you will hear of me as soon as I will have some pictures of motor holders.
 
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