[neljoshua]

Thanks for looking. If you are looking for a road-worthy electric
vehicle, one that is quite cheap to operate, easy to drive, and
minimizes your impact on the environment, this car is for you.
This is a 1983 Mazda Rx-7 converted to a fully electric vehicle
(renamed the Ex-7). The project was sort of a personal hobby, started
last June and completed in August. Here are the specs:

1983 Mazda Rx-7 GSL (limited slip differential, upgraded trim, 5 speed manual),
30 kW brushless DC motor,
10 12V 120Ah Trojan T-1275 batteries,
Kelly KBL1201H controller (Windows interface to change settings),
QuickCharge Select-A-Charge charger (just plug it into a home outlet),
Potentiometer foot switch,
120V/12V Vicor DC/DC converter (for on-board systems such as headlights),
Newer (1984?) cloth seats (may include the original leather seats if I
do not sell them separately),
Top speed: 65 mph (may be higher, but this is the best I have gotten so far),
Range: 60 mi (estimated, I have driven over 40 miles on a charge and
still had plenty of juice),
Key switch turns all systems on and off,
Working items: flip-up headlights, wipers/washer, turn signals, fan,
brake lights, dash lights (basically everything that is on the car
with one caveat--no heat currently).

Car runs and drives like a normal car. Acceleration is comparable to
other cars; however, this is not a race car, it is a daily driver.

I am a graduate student in Mechanical Engineering Technology at Purdue
University and I designed and built the system myself. The selection
of components, sheet metal design, and assembly were all done by me.
I have paperwork for all items purchased and files reflecting the work
done.

Why am I selling this? Well, a few reasons. First, we have a baby on
the way and this is not the world's most practical infant car.
Second, we would rather have the money right now. Third, I would like
to do more to this car to make it perfect, but as I am working on
finishing my thesis and we may be moving afterward, I do not know when
I will have the time.

What things would I like to do? Here is a hopeful list (you obviously
do not have to do this stuff--it is just what I am planning): add rear
seats, replace rear carpet, add cabin heat (no heat currently), add
battery heaters, replace all on-board lights with LEDs, replace and
springs with stiffer, beefier ones.

I am currently asking $7000. I am more than willing to take offers;
that being said, I do not need to sell this car, so if I am not
pleased with the offers that I do get, I will not sell it.

Email me for more pics or any questions (neljoshua@gmail.com) or call me at 765-418-7057.

Other information can be seen at http://www.diyelectriccar.com/garage/cars/149

*I forgot to mention that the car also has adjustable Regenerative Braking.

Joshua Nelson

[neljoshua]

Some have looked at this post, but I hear no feedback...any notes? Do you like it? Priced too high? Something else you want to know about?

[neljoshua]

Bump. Any offers? I would be willing to help with transportation.

[dtbaker]

did you sell it? I am amazed that it didn't go fast at that price. WHERE did you get a brushless DC motor? very cool since you get regen, but also very expensive usually.

[neljoshua]

It has not sold yet. I think I have a few interested people from another posting, but I am suprised that I have not gotten more responses. =(

In any event, the BLDC came from a company called M&C Electric Power. They are out of China (I could not find one state-side). It works great with the Kelly controller. Actually, Kelly contacted me to ask where I got the motor, as they seemed to be having problems locating a mfgr. as well. You can find these guys through Google. If someone is looking to buy one, send me a PM and I can get you their contact information.

The motor was $900 with $300 for shipping. It is plenty powerful enough and seems to be well-built. I have had no problems with the motor at all. Needless to say that I am quite pleased.

Josh

[dtbaker]

hhhmmm, it would be great if you could post the contact info; maybe under the category for OEMs and equipment, or motors.... I am sure some other people might want to try brushless to get the regen!

along those lines.... Thats why you went brushless, right? It would be great if you could share your setup and experience with that end of things. I was interested in regen, but the 'unknowns' and expense of AC scared me off. The price you got for the 30kW motor is about what a 50kW DC motor is..... so yes, more expense, but the regen would be great for a city driver!

Does the mfg have bigger motors? equiv to a 8" (50kW) or 9" power?

questions I have along the lines of regen are:
- how do you control how much energy gets dumped back into the batteries?
- what happens when the batteries are 'full', and the current should be cut way back?
- how did you trigger when to regen versus when to coast?
- how do you set the level of regen?

[neljoshua]

Dan,

I hate to disappoint you, but I am no expert as far as regen. This was why I chose a BLDC setup, but the regen feature is built into the controller.

The Kelly controller takes care of how much energy goes back into my pack. When the pack is full (or near full), the regen does not come on at all. Of course, this is not a very long period of time.

The controller came with two methods of controlling regen: a switch input and a pot input. The switch is just sort of an on/off thing. I actually used the old cruise switch for this. Thus, when I release the accelerator, the car is coasting. As soon as I touch the brake pedal, the regen comes on. This way, you can use regen without using the hydraulic system. Actually, the regen "feels" like power brakes, so I am not using the brake booster. The pot controls the amount of regen within a specific limit (set in the software, which is editable through a Windows GUI). The controller sends out a 0-5 VDC signal, and the amount sent back controls the force of regen. I have not found a combination that I am happy with, so I usually just leave it cranked up all the way. Btw, the pot is mounted on my dash where the choke knob used to be.

Now, the controller in the end determines when to use regen, so it is not always on when you hit the brake. I think that it is current-limited, but don't quote me on that.

I have a friend here at Purdue (we are graduate students) who built his own regen system with ultra-caps and all on their research trike. It works great and will stop the bike quickly. They are using a Kelly controller as well, which is why I chose Kelly, but they are using his regen function.

[dtbaker]

darn, I was hoping for a core dump I could use on my next car. I did find the site for the OEM, and it looks like there are lots of options for motor... lots of brushless DC, and bigger ones than what you got! page was
http://www.china-electricmotor.com/A...?ArticleID=296
for 'car motors'. I didn't really understand the different torque ratings between 'rated' and 'locked'. Do you have any insight to share there?

It looked like the China company also offered controllers, which presumably are set up to work with their motors... did you consider/explore buying a matched set? Or, just went with Kelly since you had some familiarity with it?

Was the wiring for the motor/controller much different to include the regen? was it published with the controller, or come with the motor, or what?

....and did you buy direct from the OEM via the internet, or have to go thru a distributor here? I am wondering why we aren't all going with the brushless DC so we can get regen without the way higher cost of AC and invertor?! Would you go brushless agani on your next EV?

I was looking at an ultra cap to store a 'braking event', and found one that holds .1F, which is just about what I calc it would take to stop a small car... but it was pretty big, heavy, and expensive!

[neljoshua]

Just sold the car last week.
If I were to do it again, I would go with another BLDC, definitely.
Wiring was very simple, and no different for one of their controllers or a Kelly. I went with Kelly because of the familiarity. There were the three main power cables, and a 5-pin connector for the hall sensor. Very easy; anyone could have done it. Btw, wiring is no different with regen or without. The only difference is in the controller programming.
I did not go through a distributor for anything but my batteries. I bought everything direct from the companies; I figured that it was cheaper and warranty issues are easier this way.
"Rated torque" is basically what the motor can give on a continuous basis. "Locked torque" is the maximum torque the motor can provide (i.e., the rotor is locked in place). The motor will overheat if it is locked for too long. The rated torque is really the more important number.
Ultracaps are a great idea for regen, but they are really costly. I am not sure myself, but I think you would need a lot more than .1F. Another graduate student designed an electric bike with a BLDC and built his own regen. They used four ultracaps larger than a cordless (not cell) phone each. I think that they were each 1F.

[dtbaker]

Originally Posted by neljoshua

J.... but I think you would need a lot more than .1F. Another graduate student designed an electric bike with a BLDC and built his own regen. They used four ultracaps larger than a cordless (not cell) phone each. I think that they were each 1F.

This is the monster i was looking at for matching the typical EV voltages. The cap is 63F.... I may have been wrong in my 'minimum' energy capture for one stopping 'event', but the voltage range plays more directly into the issue, and this was the mot likely unit. Extra capacity would mean that it might be able to suck up a little MORE than one event, but ......

http://www.maxwell.com/ultracapacito...d0063-125v.asp