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Remote "Back Window" MPG Display?

13680 Views 75 Replies 29 Participants Last post by  Insightful Trekker
Has anyone been able to extract segment driver information from the dash MPG display and been able to fabricate a nice bright large display for MPG so drivers behind me can see how I'm doing? Are their any remote MPG display kits being marketed? I think that alone would be responsible for for increase in Insight interest as much as anything else. Fred in Michigan.
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Very cool. Can not wait to see this!
Photos of the display with MPG data, and the camera mount in place.
Click rear MPG display on the main page near the phptp of my insight.
Simple piece of # 12 electrical wire was all it took to hold the camera.
The camera could use a little more contrast, so I will make or buy a video preamp so the video level can be controlled better.
The camera has a good depth of field because of the "pinhole" lens, so a perspective display can show more of the bargraph fading up to 100MPG
Lots of possibilities as to what is included in thye display.
Will update the photos and notify here as I continue to refine the display.

Mike :lol: :lol: :lol: :lol:
WOW this is really nice. Thanks for the pics

It is OT but what was the "battery monitor". I have forgotten and I suppose many where not Insight owners then. What was tested and the results.
The battery monitor was the pogo pin jack on tap into the battery connector so voltages could be read to a data acquisition system. Armin has one that he measures the battery voltage of each subpack with. He also tapped into the current sensor an is able to read true amps in and out of the pack.
I still have one or 2 of the shells without pins.

I just got back from a 50 mile night trip where I tried out the display and camera .
I found a better angle to take the video from that lets you clearly read the whole display all the way to the 150 mph bar. I will put up a picture tomorrow. The monitor that I have, which is a pretty bright 6.8" TFT that I bought on line from a surplus place. It is quite readable from about the same distance as you can read the numberplate of a car at night. The TFT has a rather narrow field of view top to bottom, so the display will need to be tuned for the best passing car angle, but once set it dosen't drift.
I looked at the camera signal with a scope, and found that the full insight display briteness gives the best contrast, but shifts all of the signals up to the clip point. I cut an RCA cable and put a 200 ohm pot as an attenuator. That shifted the voltage into a better range and improves contrast.
I wish I had a narrow bandpass optical filter that would improve the contrast of the lit segments to the background.
It is uasble as is.
The video display can be flipped horizontally and vertically, so for the hell of it, I put the display on the top of the dash and reflected it off of the windshield. I flliped the reversal switches and adjusted the TFT and low and behold my full MPG display is also displayed as a heads up color real time display that has big enough numbers and bars as to not be distracting to read even with the dual reflections.
Will take photo of the heads up display in actual driving on another night trip and put it in the photo page.

I have about 5 of the monitors (was going to be part of my future video intercom), so I will make enclosures for both.
If the tinted rear deck window blocks too much light, I will make a waterproof external display that sits right above the H onda emblem. If guys like Rick Reese and the other high milage guys had these displays, people would be reminded or how good hybrid cars are every time they got close enough. It would also allow someone to teach other hybrid drivers how to drive. The student would follow the expert, and try to match the experts MPG under the same exact conditions. Rick Reese sign me up to follow you for a few miles once you get instrumented.
The first reaction I had to having the rear display, was to reset my segment display, and start driving efficiently, because now I could imagine that the guy behind me could see how I was doing . The thing will surely need an on off switch for those days when you are in a hurry.

:lol: :lol:
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Photos of the optimized MPG rear display, and the heads up display are now available @:
under Rear mpg display.

The MPG and battery monitoring is impressive. Since I tend to be in the slow lane and get followed I have often wondered how the car behind me would respond to a real time mpg readout showing 100+ mpg. The only thing remaining would be one of those LED message boards that said if all vehicles got this kind of fuel economy then the US would be part of OPEC. Have fun, Rick
Mike: Great site, impressive scrapbook of projects!!! :)
Talk about coincidence. I was driving to work yesterday thinking about how nice a HUD would be, since I tend to pay a lot of attention to the instantaneous graph.

And there it is! Cool!

You could take your car to environmental rallys, etc.

Did you notice any reactions from other drivers while trying it out?
I did not have the display in the rear deck, so no one could see it. I had it mounted to my instrument console over the shift lever where I could see it at about chest high.
I will build an enclosure for the rear display that either is waterproof and mounts outside to give maximum viewability, or inside the tinted window which will keep it dry but because of the tint, further reduce the viewability.
I am a littlle busy installing a solar collector system for my home, but hope to have it made and running buy early next week.
I did an on line search to find out how much auto LCD video monitors cost.
The range of prices that I found was $130 to 299, depending on size and features. Add $50 for the camera, and you have a rear MPG display.
I finally had some time today, and I finished the rear MPG display. It will get some finishing, maybe an anti reflective protective glass, maybe a video amp to allow increasing contrast, and a simpler to remove mount in the future, but for now it is up and running. I put up anl Insight Modification page on my web site, where photos of the display can be viewed. I will be going out to the movies tomorrow evening, where a few trips around the parking lot when the movie gets out should see if the display has the desired effect.

See the worlds first rear MPG display @: ... isplay.htm :lol:
Wow, there's more electronics in there than a stealth fighter...
Wow !! from me too. Thanks for sharing, this is really good work.

Maybe because of the size and the distance cars behind should be, only showing the "60.8 MPG" could be enough.

Can I ask how much money it cost you to put the video monitor and the camera looking in the back. The monitor looks like an LCD type.
Hi Yves
I had purchaced 8 of the LCD video monitors at the MIT electronics swap meet several years ago from a surplus dealer for about $75 ea. and the tiny color camera was $50. I did a search on line, and found lots of LCD displays in the $135 to $299 range, most were already in a case, where as the ones I have are just the modules. The best type would be the transflective type since they are viewable in direct sunlight. If you got a smaller 5" size, you may be able to mount it inside the rear window, and focus on just the digital MPG display and get the same size image.
Have some fun, and help let the world know that hybrids really do get 60+ MPG.
I think it's to complicated. We need something a bit easier for the average user. How about a moving display on the license plate frame that is interfaced into the instant mpg indicator.
How about a series of photodiodes/transistors arranged in a row on a pcb. Put the arrangement in a matte black enclosure and have each one focus on one of the LCD segments. Tie each one to a gate that would turn on an LED in the back display. Use some kind of sensing circuit to compensate for ambient light. Doing this for one car would be a pain but if a buch of them were made up it would make a nice Insight specific kit, with an established demand. :roll:

Edit: You would only have to get one sensor/gate/LED working as all the rest are the same :idea:
While the photodiode gate concept seems simple in principal, it is quite difficult in practice. The contrast ratio of the display segments between on and off is not as large as one would like to get reliable switching even if the photo detector was placed right on the display. When I first got the Insight, I played around with trying to get a single led to light up when the MPG bargraph went into the lean burn zone. I mounted a photo detector right on the display, I also tried a plastic fiber optic to bring the light into a dark box where the photo detector as was coupled to it. When the sun got onto the display it caused the led to light even when the segment was not on. Threshold adjustment was needed between day and night even without the sun on the display. A single background light compensation photodetector was able to help, but unless it was placed right in the area of the bargraph segment that I was looking at, it could compensate incorrectly.
Detecting the 2 segments of the 100's digit and the 7 segments on the 10's, units, decimal point, and 1/10 digits would be 24 detectors that would need threshold adjustment and compensation inputs. The only way I can see to get the detectors to see the display without being in the way of your view would be to use a lens to image the display onto the detector circuit in your flat black box. The position of the box/detector to the display would be very critical, and difficult to adjust..
You would be basically making a custom 24 pixel camera. The $50 video camera already has AGC, light compensation, 640X480 pixel detector and video driver built in, alignment is easy since you can see on the video display what the camera sees.

Geoff Shepherd suggested that the video image could be sent to a computer where OCD software would decode the numbers, and then one could output 7 segment data through an I/O card. While that could work, it is even more complex .
I guess I don't see what is so hard about buying a camera and monitor, pluging it in and adjusting the lens for the view that you like?
The video solution is pretty much two off the shelf components, and a little work to mount the camera and LCD display.
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Great work! Great pix!

My only fear is that some hambone following you will be so entranced by your ability to jump multiple service stations with a single bound that he/she will rear-end you trying to read the display. :shock:

As a fellow gadgeteer, I tip my LED-equipped hat to you. Pretty work!
Mike: It sounds like you had some good ideas and experience there already. Till later, Kip.
Thanks for all the information you have posted, I will be doing my display, but to avoid other drivers following me I'd like to install a monitor just behind the drivers seat, facing at an angle, so they can see it when they're passing you on the side, so they're less likely to rear-end you, I have a "70 mpg" sticker in the back, and I can see in the side view mirror the drivers reading it, and some of them giving me thumbs-up as the pass me. :D
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