Lifetime Fuel Economy: 39.49 mpg

Wednesday, August 5, 2009


I've been contemplating this mod for a while - about 6 months. I was waiting to figure out the alternatorless stuff so it would actually be coupled with improved fuel economy, but I'm confident that I'll get that figured out soon, and my free time is running out fast with the school year approaching. Enjoy.
For starters, I had to clean up the roof.
I got this $45 piece of plexiglass for $25 at Lowes thanks to the damaged chunk. I thought this was a terrific deal until later when I noticed it is about twice as thick as the pieces I used on the Kammback, making it stiffer and more likely to split... Argh. I think I'll have to re-do this with a different material after this winter - time will tell.Plegiglass, cut to the roof's shape:Removing the remaining pieces of protruding roof-rack materials that I didn't delete yet - they're the loose pieces atop the roof.The roof's ready - or not.
I decided to paint the top white for three reasons.
1. Extra insulation from the bottoms of the conductive panels; there were bolt-holes and some surface rust on the roof.
2. Keeping the roof cooler in the sun - like school busses and mini coopers - for me, for the panels (they work better when cool), and to slightly reduce the Earth's albedo. :)
3. The silicon caulk that I plan to use to seal the plexiglass against the roof is white, so matching the roof will improve the W.A.F. (Wife Acceptance Factor)
The sandpaper to roughen up the surface:
The roof, lightly sanded:Taped off and ready to paint:Primer painted on:White paint:Now for the fun part - Solar Cells!
I bought a bunch of tabbed solar cells on Ebay in March for a project my students were doing in class. The auction was for 108 cells, way more than they could afford, but I assured them I would use the extra.
They run $2.50 apiece and are rated at: 3.7A, 0.5V apiece (1.85W) under maximum sunlight. Each cell has 2 tabs attached to the top side and two rows of solder points on the back. To attach them in series, you lay one cell's tabs atop the next cell's back, and solder at the solder points. I made strings that were 14 cells long. I was planning on doing 15 cells, then putting 2 strings together for 30 cells * 0.5V per cell = 15V for a good input to the charge controller I haven't built yet. My roof was slightly too short, so I'll probably have to put more cells on the Kammback to get the voltage up enough. I ran electrical tape across the tabs and put a dab of silicon in the center of each cell. (One string - ready to install, other - just soldered)

Laying out the strings on the roof. Yes, I realize I have 5 strings, and I can only use 4 with my plan to get the voltage I desire, but I figure if I do this, I'm going all out and I may want to put panels elsewhere later. This was my downfall; if I had only used 4 strings, I could've used the size available of the thinner, more flexible plexiglass.
I used bricks to hold the setup down overnight. Later, when I was screwing it down, I used about 15 bricks to hold the plastic to the roof's slight curvature. It helped to leave the protective peel-off plastic on until the end. (just had to remember to remove the underside when I was ready to screw it on)
Finished product photos: The back of the roof - notice one string of cells has a bit more space behind it than the other. I scooted it forward and added my homemade desiccant. I was worried about condensation on the inside of the glass looking horrible, decreasing performance, or damaging cells. I wrapped up some of my daughter's dry rice cereal mix inside a paper towel, and voila! Moisture trap! The visible wiring:More top pics:

My wife actually kind of liked it - she said it was "nice". First thing she's ever liked on this car! Now: Performance data: (preliminary)
In the shade (only using 4 of the 5 strings): 14V, 1A (14W)
Pushed the car into the sun at 2:45PM: 14.5V, 5.4A (78W)
So the whole roof is worth about 100W for probably 4-5 hours in mid-day sun after all wiring is eventually done. Cool.

Saturday, August 1, 2009

Alternatorless... or not

I recently (two weeks ago) tested the effects of disconnecting my serpentine belt while driving. Others have done this (or similar things) with much success:
Orange4boy's Toyota Previa
MetroMPG's Firefly (metro)
Daox's Paseo
The belt on this vehicle runs the a/c, p/s, and alt. The timing belt runs the water pump, conveniently.
I had tried monitoring tank-to-tank runs earlier this year without much repeatable success. This day I decided to do some A-B-A runs.
I did a 10-mile round trip run, all highway with a turn halfway, and did no pulse -and- glide, so as to maximize the effect of having the accessories running or not. I did the first couple of trips with the belt on, then did two with it off. Average FE went from 42.5 mpg to 43.2 mpg. Not convincing.
I went home and decided to do some monitoring of my voltage while driving beltless, and measured it to be hovering around 12.2-12.5V. In an effort to boost that, I connected another battery in the car to my normal battery via a 6A battery charger, hoping to get voltage up to 13.5V or higher. I repeated my test run, but alas, the voltage remained below 12.5V even with 6A coming in from the charger.
I'm not ready to call it quits, because I know there is a way to solve this somehow, in a cost-effective fashion. I know there is energy being wasted by my belt and accessories, even without the alternator being included. This should lie somewhere around 8% or higher with no belt at all, and it should show up easily in testing. Time to re-formulate a plan to delete the darned alternator system!

Friday, July 10, 2009


Finally! I had some time to play with the car after doing some needed repairs and working on the house/yard this summer. This is a good mod; it is the first one I have tested to my satisfaction since installing and calibrating my MPGuino fuel economy gauge.
The theory of this modification involves two things, changing the shape of the rear of the car, and changing the size of the rear of the car. Both contribute to dragging around a smaller wake.
The air flowing over/beside the car needs a clean, crisp "separation" edge, so a fin extending past the rear of the car will help this. Many new cars have integrated these little fins into their design to improve economy. A common and easily seen example is the back of the Dodge Caliber, but smaller ones are all over, including on the top of new truck tailgates.
Reducing the size of the wake also yields benefits, so tapering at the rear of the vehicle (at the correct angle) Typically this angle is around 30 degrees below the horizontal. From the explanation by Phil Knox, the tail on your vehicle should point to a place on the ground that is 1.78 times longer than your car's height where you want the taper to begin.
My inspiration comes from 4 sources:
Basjoos's Aerocivic
AndrewJ's civic
Darin's Firefly (Metro)
TomO's ClearKamm
Ok, on with the photos!!!
I chose to use galvanized 1/2" metal conduit for the frame. Cheap, strong, and easy to bend with a hammer. This shows how it's connected to the top of the car's hatch. A sheet metal screw through the top now holds it in place permanently:
The conduit extends 1 meter from the top, is hammered flat and bent, then attaches to the bottom of the hatch:
A cross-bar is held in place by bolts on the hatch's underside and two small pieces of conduit go down the edges of the window:
This shows the completed frame. Next step is to figure out where to use coroplast and where to use plexiglass, to cut down on the cost:This looks like it might obscure the rear visibility with this much covered with opaque coroplast, but here's the view from the inside:Not too bad. Well, the wife didn't approve. Something about "no more campaign signs on the car" and "I'm not going to ride in it anymore" Something I'm sure many other ecomodders hear all too often! Well, the solution is to spend ridiculous amounts of money on all plexiglass:Note the placement of my two shiny new Ecomodder decals courtesy of Dan (Intrigued). They are way more visible than the static clings (they really are in the photos!)And all the utility of the hatch is preserved. I just have to bend my knees to open it; the tip reaches my shoulder when I lift the latch. Just have to remember it's on there when shutting it - it almost gave me a concussion the first time! :)
Drove it around for a couple days with no problems. Many more looks than I used to get though, so I definitely need to post my fuel economy up on the car to explain all the junk on the car. I even attracted the attention of two of my neighbors who are interested in getting better gas mileage and they're going to check out the EM forum now!

Now what you've all been waiting for: Fuel economy results!
I did A-B-B-A testing (After Kammback, Before Kammback) I left the frame on and just took off the plastic. My test route for this was highway only; 20 miles round trip with an overpass-turn around in the middle. I used pulse-and-glide on each hill, but set rules: I had to reach 60 mph before each coast, and I did not coast below 55 mph. Raw numbers:
A: 55.2 mpg
B: 51.2 mpg
B: 50.2 mpg
A: 54.8 mpg
Average of B runs: 50.7 mpg
Average of A runs: 55.0 mpg
I'm comfortable saying it is worth 4 mpg highway - a pretty good improvement.

Sunday, June 21, 2009

photo-op and prelude to restart of blog

I had to include these photos from our recent trip to Colorado. Enjoy!