That is true, but that doesn't address the question -- it answers the question of why GM hammered away at NHTSA from 1989 through 1995 to get NHTSA to *permit* DRLs, which Canada mandated on 1/1/90. Interestingly, Transport Canada (Canada's equivalent of NHTSA) was going to mandate European-type DRLs which could not possibly have created any glare problems and would have used relatively little electricity. GM didn't want to add a new lighting device, and so railroaded TC into allowing the high beam and other "cheap and nasty" DRL implementations. Once TC acquiesced to GM's demands, GM turned around and started hammering on NHTSA to do likewise.
For this among other reasons, it is spurious to use DRL results seen outside North America as justification for DRLs in North America -- the implementations are hugely different.
Many things on a modern car are bigger energy drains than DRL's. You've mentioned stereo's, A/C etc. The point is the energy consumption is a weak reason to use for not installing them (DRL's) in the first place. And if energy consumption is the point of this argument, I'm sure we could all think of many other things to lower fuel consumption than eliminating DRL's. By the way I'm not for or against DRL's, I really couldn't care less I just think this "wastes gas and causes excess pollution" is ridiculous.
It's not an urban legend, but the description was a little garbled and was out of date -- the problem isn't actual emissions, it's misfire detection. I couldn't find an authoritative description, though I did find
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at a vocational school, which corresponds with what I've read elsewhere.
The basic problem is that misfire detection is hard. Detecting a spark plug that wasn't sparking would be easy (just look for unreasonable voltages on firing), but if, for some reason, the plug fires but the mixture doesn't, this won't spot it. So, an accelerometer is used on the crankshaft.
Unfortunately, driving on rough ground can cause crankshaft speed fluctuations that mimic a misfire. On an automatic transmission, the computer can respond by releasing the lockup torque converter and seeing if the misfire goes away before reporting it; it can't do this with a manual.
But, I think the misfire detection specs have been loosened up in recent years (which is corroborated but not confirmed by
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is a lot more up to date on regs than I am and no doubt knows thereal answer on that.
Dan, did you follow the original posters link? I did. In the calculations, they used 55w headlights as daylight running lights. This is incorrect as I'm sure you are aware DRL's use much lower watt lights than this, and many new cars use parking lights now. I don't dispute that it will require more energy than no lights at all, I maintain that it is insignificant and a non factor when discussing fuel economy and emissions.
This makes ZERO sense. How is turning on light going to cost gas? Answer, it's not. Your engine does not run any harder when your lights are on. Your alternator is going to spin like it always does, expending its extra power that it creates into heat. Now, when you have DRL, instead of wasting the power it's making, the power will actually be used to light the bulb.
This IS a load of crap. How is the alternator causing the engine to run harder? Answer, it's not. You're right, electrical energy isn't free, as the excess of energy from the alternator is turned into heat. Alternators also have electronic from preventing from overcharging the battery, so it's has power "in reserve" so to speak. Your engine runs no harder if you have zero electrical components on, or every single one of them. The only accessory which consumes gas (I don't consider a water pump an accessory, it's a necessity) is A/C. If you really want to save gas, ban auto air conditioning.
Now you may ask, what's the difference? Well, when you turn the AC on, it causes the AC clutch to engage, which causes the compressor to compress. It directly robs power from the engine to run that compressor. Just like when you were a kid you had one of those lights which ran off of the tire. The little generator caused drag on the tire (engine).
But the alternator is just a spinning motor, and it's going to spin whether you have DRLs on or off.
The engine DOES have an additional load on it when the lights are on, to turn the alternator under load, keeping the battery charged. There is no "wasting the power" as in your scenario.
Are you serious? Do you really think that electricity comes for free? Every last little bit of electrical load applied -- every single electrical device switched on -- causes the alternator to be harder to turn.
That's simply wrong. Start your car. Let it idle. Listen closely to it. Switch on the high-beam headlamps -- you can HEAR and FEEL the engine bog under the extra load before the idle air control increases the idle speed to compensate.
So does the alternator.
It's going to spin whether the DRLs are on or off, but it's harder to spin when the DRLs are on. That's just plain old physics -- an alternator's job is to convert mechanical energy into electrical energy. If you can come up with an alternator that's equally easy to spin when there's an electrical load on it as it is to spin with no load, go IMMEDIATELY and patent it -- you'll have invented free energy *and* the perpetual-motion machine all at once.
So you read the original article, you read the link, you saw and followed the mathematical calculation of how many gallons of gasoline are used by DRLs -- and you're still going to sit there and say they don't use any significant amount of energy. OK, that's fine, but your statement amounts to "I've already decided my opinion, so stop trying to confuse me with facts."
You obviously do not understand how alternators work. They don't just sit there "making power" all the time and "wasting it" or "expending it into heat" when there's no demand.
You're wrong here on this one. If the alternator is providing a higher current output, then the force required to turn it will be greater. This is from the increase in the opposing magnetic force generated by the higher current in the armature and/or field windings.
If turning on the light did not consume additional energy then you would be breaking the law of the conservation of energy...
If you have access to a gasoline powered AC generator (similar in design to the alternator) you can do a simple test by filling the gas tank, firing up the generator, and leaving it unloaded and then seeing how long it runs. You could then do the same experiment after putting a load on the generator. You'll find the same tank of gas does not last quite as long.
In fact, you can turn the load "on" while the generator is running and if it's heavy enough you'll hear the generator slow momentarily and then come back up to speed due to the increased load.
Actually, it's quite correct. The most common DRL implementations in North America are, in descending order:
1) High beams at 65% - 70% duty cycle
2) Low beams at 100% duty cycle
3) Low beams at 75% to 90% duty cycle
4) Front turn signals burning full time at 100% duty cycle
5) Low and high beams in series
The per-car DRL system power consumption for these systems, in the same order, is:
1) 80w to 100w
2) 90w to 178w
3) 67w to 117w
4) 54w to 108w
5) 95w to 149w
So the article's assumption was right on target.
Nope. Parking lamps are not allowed as DRLs under US or Canadian regulations. The ones you're thinking of use the front *turn signals* burning full time. That's system (4) in the list.
But you're incorrect. The maths in the linked article are proper and don't lie, but even if for some reason you think otherwise, consider this: US FECT (Federal Emission Certification Tests) must be passed by each individual model in order for that model to be legally sold. One body-engine-transmission-diff-tire-year combo is "one model". The FECT protocol requires that vehicles be configured exactly as they are produced for public consumption, so that emissions characteristics measured are representative of the cars that are actually sold onto the roads. Emissions collected during FECT are used to calculate that model's fuel economy for CAFE (Corporate Average Fuel Economy) test purposes.
General Motors asked for and received permission from EPA to run their vehicles through FECT *with the DRLs deactivated*, on the grounds that DRLs are not required by US law. However, every new GM vehicle comes with DRLs which GM will not help you disable. Now why would GM ask for that permission if DRLs did not have a significant effect on emissions and mileage?
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