550 LED light conversion

It always bothered me the various incandescent bulbs in my car draw a lot of current, gets very hot, and basically not that bright for the wattage.

A few years ago I looked into converting to LED lights, but concluded back then the technology is not quite ready. Well now it's 2012 so I studied what's available on the market last week and I now think the latest technology LED bulbs are up to the task. Here is what I chose for my 550.

 

For the reverse light OEM is a P21W single element incandescent bulb. Two bulbs per car. I chose a 7W LED light. See first picture.

Second picture shows the LED as very blue on the left and OEM incandescent as white on the right. In real life the LED is white while OEM is yellow. Color shift is due to my digital camera. In terms of brightness, to my eyes the LED is as bright if not brighter than OEM, yet draws less than 1/3 the wattage. In the time for me to take a few pictures, the OEM bulb already made the light housing hot to the touch while LED side is not even warm.

Service life of the bulb will be shortened if it's on for more than 15 minutes at a time due to heatsink cooling issues of the the LED elements. It's not a problem for me because I don't intend to drive in reverse for any extended period of time.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

For the rear position/stop light bulbs OEM is a P21/5W two element incandescent bulb, 5 watt for position and 21 watt for stop light. Total 4 bulbs for the car. I chose the LED bulb shown in first picture at 7.5 watts total in red LED color. Since the red light housing will filter out any color other than red color, a white LED means most of the light will be wasted and filtered out by the red plastic light housing. Furthermore, red LED will make the red more saturated and intense instead of washed out orange from white LED or OEM incandescent bulbs.

Second picture shows red LED with only position light on at the left side and OEM position light on the right. In the picture it's clear the LED bulb is brighter. In terms of color maybe due to it's extra brightness the LED side shows up a bit more orange from my digital camera. In real life the red LED bulb shows a much better saturated red than OEM incandescent bulb.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Dome, glovebox, and trunk OEM lights are the festoon type bulbs at 10 watts, 5 watts, and 5 watts respectively. I chose a white LED 1.5 watt bulb.

It is definitely brighter than OEM in pure white and does not get hot. I am especially stoked about the dome light. Every time I work on my car the dome light may stay on for an hour at a time. In fact the plastic dome light reflector housing has already melted a little from the OEM incandescent bulb's heat.
Image Unavailable, Please Login

 

For the fender indicator and door footlight OEM is BA9S type incandescent bulb at 4 watts and 3 watts respectively. 2 pieces each per car. I chose amber LED for the fender indicator and red LED for the door footlight at 2.5 watts.
Image Unavailable, Please Login

 

I have edited my posts to include the wattage of LED bulbs. As for the front lights I'll post up later. I am located in Hong Kong and bought all my stuff directly from China ranging from about $4 to $18 including courier charges, but US prices will probably be higher.

 

Today I did a couple of power measurements with the battery charger on to simulated car running with alternator charging the battery instead of static battery 12.7v.

Dome light: OEM rated 10watts, measured 0.72A at 13.6V or 9.8watts, LED bulb measured 0.11A at 13.6V or 1.5 watts. That's a 85% saving in battery draw and heat with better light output, wow I am really impressed.

Door footlight: OEM rated 3watts, measured 0.24A at 13.6V or 3.3 watts, led bulb measured 0.06A at 13.6V or less than 0.9 watts.

I'll be doing more tests later.

 

I have now ordered additional LED bulbs to also do the rear fog lights, front turn and rear turn signals, 3rd brake light, license plate, and vanity mirrors. Waiting for the bulbs to arrive.

I have also measure current draws of all the OEM bulbs and will be measuring all the LED bulbs as well. So far OEM rated wattage is pretty close to actual figures, but the LED current draw is even less than advertised values, which is great IMHO.

I will post up my complete results when I get everything done.

 

Dome light was an easy swap using a high power LED festoon type bulb as reported earlier. Map light is a bit more tricky. OEM is a bayonet BA9S type bulb. Due to it's horizontal position, if I replace it with a BA9S type LED bulb most of the light will be lost within the housing instead of pointing down through the projector lens. After trying a few LED bulbs I settled on a PCB board type 12 LED light with a BA9S adapter. By the way each LED had 3 light source within it, so actually 36 LED light sources. PCB board is held in place by friction and double sided sticky tape.

Picture 1 shows the housing with high power single LED festoon dome light and 2 PCB type map lights. As you can see the left side of the map housing had previously deformed due to heat from OEM incandescent bulb.

Picture 2 show interior with both map lights on. Much better than OEM.

OEM bulb is rated at 5W. I measured 0.43A at 13.6V or 5.85W. LED replacement draws only 0.12A at 13.6V or 1.63W. That's 72% savings and brighter.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

And here is a picture with only the dome light on. And with dome and map lights all on.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Next I did the rear license plate lights. Two R5W bulbs rated at 5W each in horizontal position without any reflectors and offset from the clear lens. So that means more than 50% of the OEM incandescent light is lost in the bumper housing. Hmm... pretty stupid design.
Image Unavailable, Please Login

 

The only compact size R5W type LED bulb I can find is this single LED high power unit. See picture 1.

As LED lights are very directional, OEM horizontal and offset position means more than 75% of the LED light will be lost in the bumper housing. Just for kicks I installed LED bulb as is. Yup, worse than OEM.

With some aluminmum foil wrapped around the bulb to act as crude reflector shown in picture 2, the result is then much better than OEM in picture 3 left side.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

I was away racing in the Porsche Carrera Cup support race during Shanghai F1 weekend. That was fun.

Got home Sunday night and all sorts of goodies were waiting for me. So here is the update.

I installed front and rear turn signal LED replacement bulbs. Front OEM amber bulbs are PY21W with 150° offset bayonet lugs. See picture 1. Rear OEM bulb are regular P21W clear bulbs, with the amber tint built into the light housing, see picture 2. OEM bulbs are rated at 21 watts. I measured 1.82 amps at 13.6V so about 24.8 watts.

Replacement LED bulbs are shown in picture 3 and 4 for front and rear respectively. They are basically the same bulb except the fronts are with 150° offset bayonet lugs and rear are with 180° even lugs. I measured only 0.22 amps draw at 13.6V so about 2.99 watts. Very bright amber color and bulb does not get hot!
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Due to the different current draw and impedance of LED bulbs, I expected the OEM turn signal flasher to flash at double speed as it is tricked by the LED bulbs into thinking a bulb is burnt out due to the low current draw. Sure enough it flashed double speed at about 180Hz instead of the 88HZ with OEM incandescent bulbs.

There are LED specific flashers on the market but I can only find 3 pin or 8 pin versions. OEM flasher is 7pin made by SDC, model B883 apparently also used by Alphas and some other cars. I opened up the OEM flasher, see picture 1 with the cover partially opened. I researched this subject last week and found the schematics for the timer chip U2044B. OEM flasher uses a 100KΩ resistor to set the flasher timing at 88Hz, see upper left hand corner of the 0805 surface mounted resistor 104 in picture 2.

So I tried 220KΩ resister and got a flash rate of about 105Hz. I then tried a 270KΩ resistor and got a flash rate of 75Hz. Today I back ordered 249KΩ resistor which should give me the 88Hz OEM flash rate. By the way this resistor is 0805 size 2mm x 1.25mm surface mounted.

I then tried to remove one LED bulb to see if the flasher will flash at double speed to warn of a burnt LED bulb, but regrettably it did not. There is a shunt resistor on the OEM flasher at about 0.35Ω for the purpose of comparing normal current draw versus burnt bulb situation, see middle of picture 3 the silver band. I assume this shunt resistor needs to be modified. I know very little about electronics so I'll leave this for others to figure out how to modify this shunt on the OEM flasher to retain the burnt bulb double flash speed function.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Yes, the bulb emits light at all four sides plus the top.

See my other post on the flasher.

 

OEM 3rd brake light uses ten T5 bulbs rated at 2.3 watts each. I measured 0.16 amps at 13.6V which is about 2.2 watts. I replaced them with LED T5 which draws only about 0.01 amp at 13.6V which is only about 0.15 watt.

I ground down the LED to less than 9mm diameter, then drilled out the 3rd brake light housing to 9mm diameter to accept these LED lights.

These LED lights are polarity sensitive, so have to make sure to plug them in with positive to positive.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

I offered another FChatter who PMed me to buy these LED lights from China on his behalf and send them to him in the US. If you want the same just PM me. Here is a summary of what I replaced along with measured wattage and my approximate cost of the LED replacements converted to US$ which totals to about US$270. In terms of wattage if everything was on at the same time OEM draws about 437 watts while LED will draw only about 61 watts or more than 85% savings.

Front Position light x 2pc: OEM 5.03W vs LED 0.73W US$ 5/pc
Front turn signal x 2pc: OEM 24.75W vs LED 2.99W US$16/pc
Front side turn signal x 2pc: OEM 3.81W vs LED 0.78W US$ 3/pc
Door foot light x 2pc: OEM 3.13W vs LED 0.78W US$ 3/pc
Dome light x 1pc: OEM 9.79W vs LED 1.44W US$ 5/pc
Map light x 2pc: OEM 5.85W vs LED 1.63W US$ 3/pc
Glove box x 1pc: OEM 4.90W vs LED 1.44W US$ 5/pc
Vanity mirror light x 4pc: OEM 3.54W vs LED 0.41W US$ 2/pc
Rear position/brake x 4pc: OEM 30.46W vs LED 2.48W US$18/pc
Rear turn signal x 2pc: OEM 24.85W vs LED 2.99W US$15/pc
Rear fog light x 2pc: OEM 30.46W vs LED 2.48W US$18/pc
Rear reverse x 2pc: OEM 24.75W vs LED 7.62W US$15/pc
Rear license x 2pc: OEM 4.90W vs LED 1.16W US$ 2/pc
Trunk x 1pc: OEM 4.90W vs LED 1.44W US$ 5/pc
3rd brake light x 10pc: OEM 2.18W vs LED 0.14W US$ 1/pc
Portable trouble light x 1pc: OEM 4.90W vs LED 1.44W US$ 5/pc

 

Thanks. I think you misunderstood me. I did do a xenon HID conversion using Philips kits about 6 years ago. At that time I chose the 4,300K temperature HID bulb for maximum visibility. HID ballasts draw only 35W each compared to OEM halogen 55W bulbs. Yes, they sure are a lot brighter and looks very white compared to halogen. However white LED light is more like 6,500K color temperature, so my old 4,300K HID bulbs now look a bit yellow next to the LED. Consequently I just ordered new 6,000K HID kits from Philips. Now the HID light color matches the front LED position lights better.
Image Unavailable, Please Login

 

OK I soldered in the new 249KΩ resistor on the flasher today, but flash frequency is only 82Hz. Close to OEM 88Hz but not exactly. I think it's because the OEM spec resistor is only 2 significant digit while the 249KΩ resistor is 3 significant digit. I assume the plus minus 10KΩ accounts for the difference in my flash frequency target of 88Hz.

I guess it's good enough for now, until one day my OCD acts up.