Effects of Headlights on mpg: 6%?

[COcyclist]

On North American VWs the headlights are Daytime Running Lights at 70% power. I disabled the DRLs and installed a "Euroswitch" which gives me parking or city lights (depending which side of the pond you are on). I used two yellow LED marker lights in the grill wired into a switched fuse tap for DRLs. I like the safety aspect of the yellow LED marker lights with minimal draw on the alternator. They should last the life of the car unlike the headlight bulbs you always see burned out on VWs in this country.

[redpoint5]

Originally Posted by RobertSmalls

The corner lights and dash lights draw about 90W, and headlights draw 110W according to my own measurements. For a 50% efficient alternator, that's an additional 400W (0.5HP) at the crank...

Thank you for this practical analysis.

My car has HID bulbs, which consume 35W/bulb compared to the typical 55W/bulb incandescent. That means I'm drawing 40% less electrical power. Not only does it draw less energy, it puts out 3x the light. People who appreciate FE would also appreciate electrical efficiency.

[gone-ot]

Originally Posted by redpoint5

People who appreciate FE would also appreciate electrical efficiency.

...efficiency is efficiency, regardless of whether it's mechanical (engine) or electrical (motor).

...using LESS is the goal, wasting LESS is a merely a reciprocal!

[Peter7307]

Originally Posted by Arragonis

I have xenon headlights and like others run with them on full time except in sunny weather as only the blind it seems are allowed to drive in Edinburgh

Not often you see Edinburgh and "sunny weather" in the same post !


More usefully...information from Holden (A local subsidiary of GM) states a difference of about 2% for lights on vs lights off.

The actual number varies depending on engine size , average mpg , weather etc.

This was in response to a suggestion of using daytime "running lights" as some places in Europe currently mandate.
Never went anywhere by the way.
This isn't Stockholm after all and blizzards are not all THAT common in Sydney .
Peter.