led lighting for brunnhilde - part 2

This has been a slow project, which I made no haste to complete. It is the flourescent light fixure above the dinner/lower berth. It is too bright for my use and consumes too much power compared what is possible today. I find no fault on the part of Westfalia give the year James Cook was built. In fact the company did admirable job to the length they went to contracted many custom lighting. Fast forward nearly a decade LED has come of age, with improved color spectrums and affordable. To me the flourescent bulb is ofen too bright for my need at this location. I want an ambient lighting rather than a task lighting.

As to the slow progress, partly I was undecided on the best approach to make the modification and wanted time to test out the design before commiting to the modification. Procrastinaion sometimes has its benefits. It allow me to ponder on the pros and cons of alternate approaches, without making bad decision under time pressure. Now the season in which I would make more use of Brunnhilde is approaching I spent a bit of time this morning to complete it.

For the modification from flourescent to LED bulb, my objectives are:

• reversible in case I later want to restore back to the factory confiuration
• low power consumption
• warm color spectrum similar to low wattage halogen
• keep the modification simple as well as electrically safe

After finding suitable LED light for the modification I set out to plan how to make the change. I temporarily tacked in the LED light strips into the fixture to check the illumination before embarking on the modification.

After months of testing, I was satisfied I would proceed. I begun by disambling the fixture to see what I can do to modify it while maintain the ability to return to the factory configuration. Inside the housing is a custom electronic ballast circuit board. I could remove it completely since the only thing the LED bulbs will need is the on/off switch. The printed circuit can be removed by un-soldering the connection to the on/off switch.

However I didn't like this approach as the ballast circuit board could be lost if I remove it. I also want to reuse the two power terminals since they offer secure connection. I decide to modify the circuit board to sever power connection to the electronics, while maintaining the ability to easily restore should, one day, I decide to restore back to the flourescent bulb.

The light fixture is very compact and well designed. There is no gap or cravice to allow me to bring the wiring of the LED bulbs to the ballast compartment, however hard I try. I drilled a small hole on the plastic housing to bring the wires to the back side for their entry to the connection points on the ballast PCB.

a 1/4" hole for the wiring created

 i secured the two LED light strips with 3M VHB adhesive tape

the thin wire transition is required to be able to replace the plastic insulating plate; there is a small incision on the circuit board to severe power to the electronics

 here you can see the two power terminals are reused for a secure connection to the vehicle wiring

a small cable tie secure the wiring instead of bothering with tacking the long wires to the plastic body - i always like keeping things as simple as possible

 testing before installation into the vehicle

since the fixture has no reflector, the forward facing beam pattern of the LED lights works very well; the fresnel defractor lens do a good job of diffussion

the illumination is very even thanks to the fresnel lens

The power consumption of the LED lamps is 200mA total.

link to: led lighting for brunnhilde part 1