Project: The Electric Booger (budget EV conversion - '92 Mazda MX-3)

[pete c]

Great job so far. I have a suggestion for heat.

You are currently using precious electrons to generate it. Meanwhile, you have a fairly hot motor under the hood. Why not get a length of fairly small diameter flexible copper tubing and wrap that motor, good and tight. Cover it over with fiberglass batt insulation. Install a small 12v circulator pump and run the coil directly to the heater core. I would leave the resistance heating in place for when it is needed (sitting in traffic or at start up).

During thw warm weather either remove it or add another heater core somewhere under the car to bleed off the heat.

[MetroMPG]

Sounds like he can heat the car with his inefficient battery chargers too.

[mechman600]

Originally Posted by ctgottapee

I have seen that people who do PS deletes T that line and put some sort of breather on it. That way you don't have to steer against the pressure of the looped hose, but still can keep some fluid in there

Thanks for the suggestion. I will eventually put a tee in that hose and run another hose vertically as some sort of a breather....we'll see.

Originally Posted by pete c

Great job so far. I have a suggestion for heat.

You are currently using precious electrons to generate it. Meanwhile, you have a fairly hot motor under the hood. Why not get a length of fairly small diameter flexible copper tubing and wrap that motor, good and tight. Cover it over with fiberglass batt insulation. Install a small 12v circulator pump and run the coil directly to the heater core. I would leave the resistance heating in place for when it is needed (sitting in traffic or at start up).

During thw warm weather either remove it or add another heater core somewhere under the car to bleed off the heat.

The motor doesn't get hot enough for that. After my commute home up the hill I can hold my hand on the motor case and commutator/brushes. They aren't cold by any means, but not hot. It has also been suggested that I direct cooling fan air into the cabin. This I feel is not a good idea because with all the arcing and whatnot going on at the commutator, I'm pretty sure the air going through there wouldn't be very good for my health.

On another front, it really pains me to say that I have given up on Paccar Dual-Purpose truck batteries. Simply put, my car murders them VERY quickly. I have spend the last week crunching numbers on various battery options. I need to do something fast or I will be walking to work. I have two good group 31 AGMs in my pack and another [identical] AGM running my accessories.

Option 1: Lithium. $3839 for 100aH (including HST sales tax) + shipping. That's WAY more than the $2250 I have into the car so far.

Option 2: Walmart Marine Batteries. 10 X $1000 + HST = $1120. A cheap pack but are they going to last any longer than my current style batteries? I doubt it.

Option 3: I found out that the Paccar (did I mention that I work at a Paccar truck dealership??) BA29D51 AGM "Dual Purpose" battery is made by East Penn/Deka (Same as MK) and is a 8A27 (group 27). I can buy them at cost for $147/ea, and then I only need 9 because I can use all three of my current AGMs. That totals $1482.

What did I choose?

Option 3. I kind of gave it way with the smilies, didn't I? And I'm pretty excited. I know I have now blown the budget away but at least I will get the performance bonus of AGMs. For those of you who don't know, AGMs have FAR less voltage sag than floodies, and FAR less peukert effect, meaning more range with less aH. They also do not quickly go bad when left with less than a full charge. These 8A27s are 92aH X 2 X 72 = 13.25 kWh.

I took delivery of two of them yesterday (the rest are on backorder) and replaced my weakest pair with them. The drive home revealed how strong they really are. Close to home 3/4 of the way up the hill, all floodie pairs were at 9.0-10.0V, my oldest AGMs were 11.2V and my new pair was at 11.3V. I am excited for next week when everything stays above 11V at WOT!

Next is my PWM field controller assembly.
Then is the Rudman battery balancer assembly & 72V charger.
Then I hope it's done...

[MetroMPG]

Originally Posted by mechman600

Simply put, my car murders them VERY quickly.

Oh! Blaming the car for how far you're pressing the "battery murder pedal", eh?

...the way up the hill, all floodie pairs were at 9.0-10.0V,

Generally, drawing a 12.5 battery below 10.5 volts under sustained load is considered risky - chance of cell reversal (murder).

That of course limits how much current you can pull - which is the price for not murdering elderly batteries!

[mechman600]

Originally Posted by MetroMPG

Oh! Blaming the car for how far you're pressing the "battery murder pedal", eh?

Generally, drawing a 12.5 battery below 10.5 volts under sustained load is considered risky - chance of cell reversal (murder).

That of course limits how much current you can pull - which is the price for not murdering elderly batteries!

I know, I know.

I originally had set my controller to a battery voltage min of 63.0V (1.75VPC, 10.5V/battery), but after a few km of driving, performance was embarrassing, especially at the beginning when I was switching batteries in and out to get a "decent" pack. I posed "the 10.5V question" on the diyelectriccar.com forum and one guy said even 1.5VPC is okay for some batteries once batteries are going flat and are sagging like crazy.

Right now I have voltage minimum set to 55.0V, but at 55V, strong batteries may be at 11.2V while old junky batteries are at 7.0V. It's all about watching each battery voltage, but since my new pack is on its way, I don't really care. As long as they last a few more days!

[turbovr41991]

I always liked this bodystyle and it looks to be to be extremely aerodynamic.

[Daox]

You would think that (I did too), but its no better than most cars from its era with a Cd of .32. Thankfully frontal area is a mere 18.8 square feet for a total cda of 6.20 which is pretty decent.

[MetroMPG]

It sure appears that car is "shape-optimized" to have good Cd, which means the reason it's not particularly good lies in the details: cooling openings, air dam, mirrors, wipers, wheels/tires, underbody, etc.

Fortunately, all those details can be more easily modded than the overall shape can be.

[Cd]

Originally Posted by turbovr41991

I always liked this bodystyle and it looks to be to be extremely aerodynamic.

It sure would be nice to see a complete body tuft test of the MX-3 to see just where the problem areas are with the car.


Besides needing a sharp break in the bodywork at the rear quarter panel, I can't see what makes the Cd so lousy. Perhaps it has to do with the tires sticking out into the breeze at the bottom of the rocker panels ??
I know that the Cd dropped to .31 with the factory body kit that added a small diverter in front of the tires.





The underside is a mess on the MX-3, but is it really enough to drive the Cd up this high ?



To me, the car looks to be a diamond in the rough shape wise. When seen from the top, the car does not taper inward at the rear quarter panels like the Insight, however, the glass has a very nice curve.



Also consider the rear curve on the LS-430 was very minimal when seen from the top, yet the car achieved a .25 Cd .



If the aerodynamic problem areas on the car could be found, it would seem an easy way to extend your range with this car.

Here is a thread i started on the subject : http://ecomodder.com/forum/showthrea...3-a-15815.html

[mechman600]

Personally, I think the MX-3 looks gross. It may have looked okay in 1992, but it sure hasn't aged well. And why are MX-3s all green?
Now you know why I named it what I did.