LED lighting

View in the dark Now, the fun part. All the external lights except the head lights and the front markers are LED clusters. The advantage I see is high reliability (LEDs won't burn out), low current consumption, consistent pure colors and distinctive look. Another thing I took advantage of - arranging the rear lights LEDs into a matrix display allowing to indicate the status of the chargers without even coming close to the car. More on that - below. So, my stop lights, side markers, parking lights, and turn signals are in new form now. Amber in front and red in the back.

Well, there is more serious reason for doing it: LEDs turn on about 100ms quicker than incandescent light bulb. While doesn't sound a lot, at 65 mph the car goes about its body length in this 0.1 second. So if I see the obstacle on the road and hit the brakes, if the driver behind will react 0.1 second earlier hitting his brakes, all else being equal he will stop a full car length further from me. This simply means that if in such extreme case he stops 2-3 feet from my car, if I wouldn't have LEDs, he would "kiss" my rear bumper...

LED matrixSo the first step - taking stock lights off and make room for the PCB with the matrix of LEDs mounted on it. I started with rear combo lights. On my Honda whole assembly is made of plastic so it is easy to cut away the spherical sections holding the light bulbs and making the surface smooth enough. Dremel tool is of big help here. When all the lights are prepared and cleaned out, I measured the size of the available area inside and cut the carton template to see how it fits in the light shell. After trimming it I got exact size of the PCB to be made. Well, I ended up using perforated prototyping board, which in a way was a mistake - it tripled amount of work to interconnect all the LEDs in right sequence. If I were to do it again, the PCB is the way to go. Anyway, after all the LEDs were arranged in the nice rows and soldered in, they were connected in series of 2, 3, 4, 5 and 6 with the current limiting resistors. The chains with two LEDs start glowing first (at about just 5V). When the voltage increased, the groups of 3 LEDs come on, then 4 LEDs, etc. At 14.2V they all lit at full brightness with 20mA of the current through each chain. These are high output LEDs (red ones are 7000 mCd, amber are 9000 mCd) so it may be painful to look from the close distance to all of them lit. 

LEDs Rear combo lights (back side). Yellow turn, red stop, two red rear markers and one red side marker.
LEDs The bulbs are removed and the plastic is milled out with Dremel tool to expose the lens. Half way done here.
LEDs The piece of prototyping PCB with the matrix of the LEDs soldered in their position. About 200 LEDs make up rear brake and parking light here.
LEDs Zoomed in view of the LED matrix.
LEDs Side view of the turn light PCB with yellow LEDs. Note different angles LEDs are facing.
LEDs Both PCBs are connected to the original harness - front view.
LEDs Both PCBs are connected to the original harness - back view.
LEDs Front turn lights PCBs - front and back view.
LEDs The same - side view (before interconnecting LEDs)
LEDs PCBs installed into the plastic shell. Note turn light PCB is installed at about 45 degrees angle.
LEDs Close up of above.

The same modification was done for the front lights (marker and turn) and the rear central . Special attention has to be paid to the protection from the moisture that will corrode the soldering joints over time. I've used RTV silicon compound made by GE - great stuff for keeping the water out. Entire shell is covered from inside and when the compound "hardened" you probably could use the light underwater - nothing should happen to it.

LEDs The central brake light - front view.
LEDs The same - rear view.
LEDs The front turn signal light - small PCB is installed and sealed with RTV compound. Yes, I can't easily remove it, but when was last time you had to replace failed LED?

Turn and marker lights Well, here are a few photos what the result look like. It was very difficult to take an image of the light source with a digital camera - I was unable to get red color on the image from the red lights. Aura around is red but the LEDs turn out to be white - may be camera's CCD got saturated or something similar. Anyway, the white looking LEDs are actually red. And, in the dark it is painful to look straight to the brake lights from a short distance. Not all the possible lights are on the photos, like single yellow charger status LED of two red "Failure" LEDs. I'm sure you got the picture though. Here it is:

LEDs The left charger is on.
LEDs The charger is off, but still is plugged in (as when the charge is finished).
LEDs Rear marker light. It's red!
LEDs The turn light.
LEDs Hard to tell what it is, but this is front side marker/turn light.
LEDs Front turn light
LEDs Brake and marker lights are on.
LEDs Overall view. Both chargers have finished charging cycle and shut off. This info remains until unplugged from AC mains.

Are you having fun? If so, here are some more photos for you taken in the dark:

LEDs Markers and chargers are on.
LEDs Marker and stop.
LEDs Marker and turn.
LEDs Just the rear marker. Small side marker is visible too.
LEDs Close up "on"
LEDs Close up "off" and "plug"
LEDs Brakes are on.


User interfaceGood instrumentation is essential to stay informed of what is going on in the car. Despite common opinion, for monitoring fluctuating values nothing beats a good analog meter. Because of inertia of its movement, it averages out spikes and noise in the measured signal so you get "filtered" output. Digital displays have be updated and you have to think what are you seeing. In analog meter you can use color backgrounds on the scale to indicate acceptable or dangerous zones, so quick glance on it will tell you the story instantly.

In my case the inverter came with diagnostic software which allow to display any inverter parameter on the PC screen in digital, analog or binary (or any combination of these) form. Besides, I can select only these instruments which display relevant for driving information. As the PC and displaying module I use Fujitsu Stylistic 1200 pen based computer with monochrome transflective screen. The main advantage is that it is well visible in direct sun light, like a digital wrist watch - the brighter the better. Of course, for dark conditions there is backlit. So, what I have configured to be displayed (and updated in real time as I drive) on the screen is:

- Battery pack voltage
- Battery current
- Battery power
- Motor power
- Motor torque
- Inverter's power stage (IGBTs) heat sink temperature
- DC-DC converter heat sink temperature
- Motor windings temperature (2 points)
- Acceleration pedal demand value
- Regen brake pot demand value
- Motor shaft speed (RPM)
- Error buffer status

Also all the same info in digital form.

Dash Overview of my dash board
Dash Side view. Interface connections are visible.
Dispaly Close up of the Stylistic 1200 PC mounted on the dash.
Display All I want to know about the status of the system.
Display Any parameter can be changed on the spot, taking effect as soon as I hit <ENTER>. Even while I drive. Great for fine tweaks.