vonplyr

Question: Does having your headlights always on during the day use up a significant amount of battery or gas? What about the factory installed LED lights (in the cupholder and feet area)??

aznJ

after the car is started and the engine is running, all electronic devices should run off of the alternator so that the drain on the battery is practically insignificant. That is why when you start your car, your stereo and lights dim or shut down and then start back up. The power is switching from draining the battery only to pulling power from the alternator. Although it is the engine that is spinning the alternator, i don't think it would effect the engine since it is always spinning the alternator no matter what, that's what's providing the electricity for your spark plugs.

If you are running a lot of electrical equipment in your car, all at once, it will put a strain on your alternator, because you may be drawing more amperage from your alternator than it was designed to put out, but it should not affect the engine's performance in any way.

I think i have my info right, a combination of 3 years of electronics and automotive technology classes have to have been good for something. If anyone's got any better info, correct me please. I'd hate to give someone bad info.

Somnambulated

Haha, no, you sound right on track. I'm driving my tC with the lights always on too, and I wondered if anyone else was doing it.

I dig the daytime running lights/parking lights.

hawkeye

However, the increased load on the alternator from the extra current draw would cause the alternator to work harder (harder to spin) and so you would have a negligible increase in parasidic drag.

Nothing you would ever notice, though.

JasonH

Yes, driving with your headlights on all the time will lower your gas mileage. Will you notice? Probably not. But the manufacturers do (since a very small reduction in mileage times millions of cars makes a less insubstantial difference.) I recall that manufacturers were working on LED daytime running lights because they draw so much less current that they would have a much, much smaller effect on mileage. The under dash and cupholder LEDs draw so very little current compared to the headlights that it really makes no difference.

engifineer

Yes, you will get a small amount of extra drag due to the extra load on the alternator, but not enough to notice. And the led kit will add practically nothing. Most LEDs pull no more that 20 - 50 mA, that is why they are so good to use, they don't take much to run. Even if they were left on without the car running, it would take a very long time to even drain the battter a little. But, the tC has that cool feature that turns off the lights when you mistakenly leave them on.

2eZee

I would NOT always run with full headlights on Night and DAy.

your alternator needs some amount of driving time to RECHARGE the battery and not just passby with juice needed at the time.

USe the parking light mode on sunny days when it is not cloud covered or dark.


You will fail the alternator sooner if you dont.
so thats a fact,
I will say running the Tc 27 minutes a day without FULL headlights on will keep your battery in peak condition. If you snooze you lose : )

Rivulent

We're talking about brand new alternators here though people, I don't think this should be anything we worry about for at least 5 years. You won't see a noticeable difference in gas mileage (lol) if you have your lights on all the time. If you're that concerned with MPG, shouldn't have gotten this hog of a 4 cylinder. Not trying to be a jerk when I say this, but running with lights on could be no worse than having your speakers set at 30-40 volume.

I have no idea how you got 27 minutes a day, becuase that would be dependant on how much you drive it anyway. But you're absolutely right 2eZee, it will put an extra strain on the alternator.. but I don't think it will make your alternator fail much sooner (if at all in the time of ownership).

All I can say is that we shoudln't be stressing such a trivial matter (at least, trivial at the moment as there are no alternator problems surfacing yet). If you have the feature to just leave them on, and you don't mind them on, just leave them on. As far as your alternator needing to recharge your battery goes, the alternator always has a load, and adding a tad more won't prevent it from doing it's job.

Just a final note, I'm not trying to say any of you are wrong, but there's no need to blow something like this out of proportion.

aznJ

oh... i've never heard of that before.

An alternator works because the spinning magnets on the armature creates a magnetic field which creates an electrical flow in the coil that's wrapped around the stator. I don't understand how anything could cause more resistance on the spinning of the armature. Does pulling more current create an opposite magnetic field that slows the armature down?

an alternator puts out a constant amount of amperage, and each electrical device draws a certain amount of amp. If your car is wired correctly, when you draw more amperage than your alternator puts out, the amperage put out to each device is lower. Hence headlights dimming when the bass hits in a powerful system. It's called overdrawing your alternator, but you aren't actually overdrawing, it's just that one electrical device is pulling more amperage so it pulls that amperage from other devices.

I'm not trying to argue with you or say that you are wrong, you may know more about it than i do.

2eZee

I have decided to never turn on my headlights. : P

panasoanic

On alternators, more load means more drag. Here's why (taken from another forum):

onefunkyfreshdj

I know that when I run with my headlights on I get about an extra 16-18 hp at the wheels & it uses 3-3.5mpg less than without.
So are you guys saying that if I were to live in Alaska where it's dark outside for almost 5 months a year I will have to get a larger alternator cause I have to use my headlights all the time?
I would have to say that you guys lost 10% of your brainpower just by reading this incredibly stupid post. sorry.

eov32885

i have my lights for most of the time,and lights on my parents 4runner are always on, you can't turn them off..and it has over 120,000 miles and they haven't given them a problem

otacon88

you think the alternator would be too strained if i had the LED interior lights, subs, lights, and underbody neon kits all on at once??