Daytime Running Light

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Why wasn't this thread transferred to the humor section? On my DRL less truck, I am quick to put the headlights on if it is hazy or the sun is low. I don't think mileage falls off that much at night when you run the head lights. Let's get real. If you are really serious about saving gasoline, dump your big guzzler you don't need and go for a 50-100% increase in mileage.
 
quote:

Originally posted by labman:
On my DRL less truck, I am quick to put the headlights on if it is hazy or the sun is low.

You are most certainly in the minority. It seems like I'm always flashing people at night because they have no lights on.
 
Many cars without DRLs simply have a relay that allows you to leave the headlight switch on all the time.

Turn off the car, the relay drops out, off go the lights. Car on= relay on= headlights on. We just leave the headlight switch on all the time.

It's how my 93 and 97 Camry and 02 Highlander work, and would seem to be how ANY car with a normal headlight relay would work.

Surprisingly the 02 Highlander does not have DRLs.
 
Even with headlight relays, most cars still don't turn the headlights on and off with the ignition.

If my car did that, I would find that to be a really annoying feature, since I can think of a number of situations where I might want the headlights on without the key in the ignition.
 
the headlight switch overrides and turns on the relay and therefore the headlights whenever the car is off.

The way mine works is that if you leave the switch ON, then turn the car OFF, the headlights go OFF. So far so good. But that's not your issue.

Then I can turn the headlight switch OFF then back ON, and the headlights come on without the ignition being on.
 
The functionality you've described requires more than just a single, standard relay, so even cars with headlight relays would still need additional components to work like that.
 
I know mine has a timer, or maybe it is built into the relay. It keeps the lights on for 1 min, after the ignition is turned off and driver door opened. W/o my key, manually turning off and on the switch stakk will turn on the lights, before it times out after the minute. Repeatedly turning it on and off will override the timer and keep the lights on, but you also risk ruining your battery.
 
Personally I dislike turning the lights on during the day - the displays for clock and temperature dim out and get very hard to read.
 
quote:

Originally posted by Jonny Z:
Personally I dislike turning the lights on during the day - the displays for clock and temperature dim out and get very hard to read.

I wired a switch into the wire from the lights to defeat that on my 92 Grand Am. It didn't have DRL, and I used the headlights frequently on dismal days.
 
The power for the lights has to come from somewhere. It comes from the alternator, which, in turn, gets it from the crankshaft.

At 100% conversion efficiency, 1 hp = approximately 746 watts. With typical inefficiency, figure 1 hp = 500 watts. So 50 watts load equals about a tenth of a hp.

The horsepower needed to keep a car going at a steady given speed varies based on a lot of factors, but is probably in the range of 10 to 30 hp.

So, the DRLs add maybe 0.33 to 1.0% to the power demanded of the engine.

I suspect you would save much more than this by making sure your tires were properly inflated.
 
Just a correction here, but Canada has DRL's since the 1990 model year. All cars built after december 1989 to be exact.

They are invaluable on 2 lane roads, for passing and in bad weather, rain, snow, fog, road spray, etc.

And in these conditions, the low beams or high beams at reduced intensity are much more visible than amber DRL's, such as seen on many GM cars and Chrysler minivans.

My Corolla DRL's use the low beams at I guess around 80% but I prefer the Honda DRL's which run the high beams at around 50%. So if a bulb goes, you still have both low beams intact.

Here, it seems that most japanese cars have a switch for the DRL's in the handbrake lever. So to reduce draw on the battery and alternator, I always pull my handbrake 1 click before starting the engine, and just release it when I start driving. Not a bad thing to do in the winter if you start the car and let it run a few minutes while you scrape the ice or the snow that has accumulated while it sat.
 
I used 15% engine efficiency, 70% alternator efficiency, and 140,000 BTU/gallon energy content of gasoline to calculate the fuel used to generate electricity in a car.

White LED lighting would reduce the lifetime cost of car ownership, and eliminate the need to change light bulbs. They can be used for DRLs, and instrument cluster lighting, but not yet for headlights, since they cannot be focussed well enough.
 
quote:

Originally posted by oilyriser:
I used 15% engine efficiency, 70% alternator efficiency, and 140,000 BTU/gallon energy content of gasoline to calculate the fuel used to generate electricity in a car.

White LED lighting would reduce the lifetime cost of car ownership, and eliminate the need to change light bulbs. They can be used for DRLs, and instrument cluster lighting, but not yet for headlights, since they cannot be focussed well enough.


Engine efficiency for gas motors is about 30%, not 15%.
 
quote:

Originally posted by Matt_S:

quote:

Originally posted by oilyriser:
I used 15% engine efficiency, 70% alternator efficiency, and 140,000 BTU/gallon energy content of gasoline to calculate the fuel used to generate electricity in a car.

White LED lighting would reduce the lifetime cost of car ownership, and eliminate the need to change light bulbs. They can be used for DRLs, and instrument cluster lighting, but not yet for headlights, since they cannot be focussed well enough.


Engine efficiency for gas motors is about 30%, not 15%.


Low heating value for gasoline is about 120,000 BTU/gallon, not 140,000. 30% is bit high for normal car under neormal highway operating conditions. It's closer to what agasoline engine will develop at peak efficiency, Still cloer than 15% tho.

Depending on who you listen to, 70% efficiency may be too high for an automotive alternator. Some claim as low as 50%, that sounds a bit too low, they don't seem to kick off that much heat.
 
If you don't have your headlights on and some moron doesn't see you and pulls in front of you, and you have to brake and reaccellerate, there goes your mileage.

But that dolt might have pulled out anyway and you'll never know what's going through their head.
 
What people so inconsiderate about is the truth of the alertness as one limited source. Depending on the performance we demand it fades out, sooner or later. Attention fatique. So too much stimuli, one light for everything is not always a vise move.

I use low beams whenever necessary, but typically, not on one-way highways, unless too crowded and speedy.
 
"White LED lighting would reduce the lifetime cost of car ownership, and eliminate the need to change light bulbs. They can be used for DRLs, and instrument cluster lighting, but not yet for headlights, since they cannot be focussed well enough. "


why can't they be focused? Light waves are light waves.

I think the bigger problem is simply the lumen output isn't high enough. Focusing would help but you still need a lot more light output. There is a huge difference is being able to merely see the light (DRLs, brakelamps) and being able to actually illuminate something (headlamps).

I think the cost arguement is misleading as the initial cost is many times that of tungsten/halogen and the life expectancy of the old stuff isn't bad at all. Maintenance costs might be lower but initial cost is much higher, so much so that the lower maintenance costs are moot. Repair costs are incredibly higher, so insurance may be affected.
 
I like the DRLs on my '72 Plymouth. If I think I need them on, I have a push-pull switch that I pull out. When I think I don't need them, I push the switch in.
 
quote:

Originally posted by kenw:
"White LED lighting would reduce the lifetime cost of car ownership, and eliminate the need to change light bulbs. They can be used for DRLs, and instrument cluster lighting, but not yet for headlights, since they cannot be focussed well enough. "


why can't they be focused? Light waves are light waves.


Seems like that fact that LED light wave are coherent would make them easier to focus.
 
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