DEcosse
If it's no Scottish it's CRAP!
I guess the improvements made to the newer Roadsters, where Triumph didn't run the feeds through the ignition switch, hasn't helped light output. The ignition switch may live longer but illumination may be worse. Where do they run the leads now? High/low beam switch???? (I don't have a manual).
At least per the late model schematic I'm looking at, the power for headlights STILL goes through the Key-Switch
From Key-Switch to Fuse Panel to Headlight/Starter Relay, from there directly to the hi/lo switch and out to the lamps.
What is slightly surprising is that the HiBeam loss was lower than the LoBeam (sure you got those right way round?) You would expect the higher current of the high beam filaments to cause higher volt drop
With 8000 kms on my new 12 Roadster, don't really care about any warranty issues this might cause.....
Don't know about CA Gregger, but a modification to your lighting circuit should not globally invalidate your warranty i.e. if your transmission failed, what could that possibly have to do with your Headlight mod?
Certainly in the US the warranty cannot be universally invalidated by mods and further the onus is on the Manufacturer (not the owner) to PROVE that a modification directly caused the failure under which a warranty claim might be denied. I love it when the law is based on 'common sense'.
Even in countries where the law does not specifically cater to modifications, you might hope that a dealer/Triumph would honour warranty on a genuine unrelated failure.