Headlight upgrade: Relay circuits
As Sebastians Article about restoring the W124 headlights was a good point to catch up i thought about showing how further improvement can beachieved. Theres a quite simple way to upgrade your headlights and gain more light ouput without either destroying the OEM look nor being highly skilled in electronics. This can be done with building in relay circuits. But what is the point of that?
As you surley can imagine the electricity has to go long distances until reaching the headlights. From distributor X4 to the light switch, over to the high beam switch. Then moving through the fuses, the headlight controller with final destination being the headlight itself. When metering the no-load voltage the result where 14,3 volts at the battery at 800rpm idle. The right headlight only received 13,13 volts, the left one 13,35 volts. The voltage loss is due to resistors and doesnt sound too bad. The results after the upgrade will teach us better!
Lets get started!
A specialty of my circuit will be the that it wont leave any marks within the system. No wires will be cut that would need soldering once removed. Nobody will ever remove this gadged again but anyway! Some minor circuit plan reading skills are needed as i wont describe the building process.
Main goal was to have a solution that wont affect the stock look without cutting any wires. There are solutions with OEM relays but these parts lack 2 connections and cutting wires would be the result. Besides a voltage and resistance measurement i also measured the headlights brightness in LUX, before and after the upgrade.
Installing the circuit is quite easy. First of all disconnect the battery. Then open up the fuse compartment by unbolting the 6 screws on top of it. Another screw is placed within the compartment right in the front and then you are ready to proceed. No you can lift the relays and have them mounted to the hood. No you need to move underneath the dashboard:
To have the relays working we need to ground them on clamp 86. You can search for suiteable connections within the fuse compartment like we did or use any connection you might find!
Last point on the agenda, shrink hoses around the wires and dump the complete setup down into the fuse compartment.
I hope i dont need to tell you that working on the electronic system is totally on your own risk.
At the end i collected all metering results which i had before and after the upgrade. Hope you enjoyed this little article and maybe it helps to lighten up some of you! 🙂
|Battery no-load voltage||12,57 volt|
|Battery no load voltage at 800 rpm||14,34 volt|
|Fuse compartment before fuses||13,82 volt||14,05 volt|
|Fuse compartment after fuses||13,59 volt||13,93 volt|
|At the headlight (low beam)||13.35 volt||13,67 volt|
|(ohne Last 14,0 Volt)|
|Fuse compartment before fuses||13,79 volt||14,00 volt|
|Fuse compartment after fuses||13,59 volt||13,90 volt|
|At the headlight (low beam)||13,13 volt||13,46 volt|
|(no load voltage13,98 volt)|
|Brightness in LUX||9.390||11.700|
|-All metering results against ground at the battery|
|-8 ampere fuses replaced by 16 ampere|
Regards Oliver (ollib)