4-Runner Headlights "always on" options

toyota
4runner
lights

#1

Since I bought my Toyota 4-runner in late 1999 when many manufacturers were lighting up the headlights at low voltage any time the car was running, I have found that this eventually puts a bit of extra strain on the alternator and battery. Does anyone know of any way to disable this “safety option” (which by the way most manufacturers have abandoned now) without harming the headlight circult or blowing anything else up on the truck??


#2

Daytime Running Lights (DRL) have hardly been abandoned. I see more and more vehicles with this feature every day.

“A bit of extra strain.” What, exactly, does that mean?

Yes, there’s probably a way to disable the DRL, but why bother? The headlights at low voltage aren’t hurting anything, and they just might be a “safety feature.”


#3

The DRLs take much less electrical power than the fuel pump, engine fan, AC fan, and so on. I doubt that you could tell any difference in alternator life with them or without them. Look at it this way. Every bit of load on the alternator results in more load on the engine, thus reducing MPG. Car makers are very focused on getting every fraction of an MPG that they can for each model due to government requirements. I don’t think so many would make DRLs standard if they had a detectable reduction in MPG. Therefore, they must not put much load on the alternator.


#4

I’m inclined to agree with the OP. I had a Chevy with DRL and they were far fron “low voltage” And like tardis says “Look at it this way. Every bit of load on the alternator results in more load on the engine, thus reducing MPG”


#5

the alternator runs at the same speed varying with engine rpms regardless of whether the lights are on or off. It does not affect the mpg in any way. The voltage regulator automatically adjusts the charge to the battery as load and engine speed vary. so, the only draw back to lights on at all running times is that the bulb life will be less. Nothing else is affected.


#6

the alternator runs at the same speed varying with engine rpms regardless of whether the lights are on or off. It does not affect the mpg in any way.

Umm…Wrong…When there’s an electrical load and the alternator is being taxed heavily to recharge the battery and run the electrical components the physical resistance to turn the alternator is MUCH MUCH harder then when there’s no load on the alternator (in fact at the Boston Museum of science they use to have an exhibit that proved that…THUS…providing worse gas mileage…How much worse is the question. Probably a max of 2-3mpg…Many people who put in these mega-watts sound systems put in 200amp+ alternators…that can decrease gas mileage by as much as 4-5mpg…If in a 4=cylinder engine…maybe even more.


#7

be that as it may, the head lamps dont pull that much current. brushless alternators dont load down, not like the old generators did, so I dont see how it can make any real difference in the alternator life or the battery life either for that matter.


#8

and I seriously doubt it would measurably affect the mpg.


#9

I agree with that…Headlights won’t pull that many amps to be an issue.


#10

Studies have repeatedly shown that DRLs reduce accidents. Highest accident rates are at dusk and dawn, and I’d bete that the first thing the cops hears at most scenes is “I never saw the other car”.

As to the energy issue, it uses a tiny bit of gas but does not place signifcant load on the electrical system. Every bit of energy the car uses originates in the gasoline. Including lights. The reason lights use a bit of gas is because the additional current being drawn through the alternator’s windings creates a bit more resistance. Remember that the alternator works by passing windings through a magnetic field. It’s an inductive device. Boost the field around the windings by adding more current and pulling one field through the other becomes a bit more of a challenge. That load is placed directly on the crankshaft, so I guess it could be argued that rather than loading teh electrical system the lights put a tiny bit more load on the crankshaft.

But you’d be hard-pressed to measure the difference in MPG. The lights are a tiny part of the gas usage. Gasoline can produce about 39,000 watts of power per hour.
http://www.evworld.com/library/energy_numbers.pdf
The typical car headlight is about a 55W bulb
http://hypertextbook.com/facts/2005/YatManTsui.shtml

Even if you consider th eeverage engine’s rughly 25% efficiency in converting the power in gasoline to engine power knowing the the power to run the lights comes dierctly from the engine, and even of you figure losses in the generation of electricity, it’ll still be a small amount.


#11

DRL’s aren’t on cars because the car makers are benevolently looking after our safety-- they’re there because they’re required by law in Canada and they want to reduce the model variation between North American models. I suspect part of the reason why DRL’s aren’t quite as common as they once were in the US is that now most cars have headlight modules that makes it easy to have a toggleable DRL-mode.

There was once a genuine debate about the safety of DRL’s back in the days when they were literally just having the headlights on all the time, since sometimes the increased glare made things worse (especially for motorcycles). But the separate low-wattage DRL’s are pretty unreservedly a good thing.

As the other posters have pointed out, worrying about increased wear and fuel consumption from such a low-power user is pretty ludicrous. There’s some parts of the world where they have problems with collisions at night because of peoples’ erroneous belief that using the headlights uses a significant amount of fuel and so they won’t even use them at night.


#12

.Many people who put in these mega-watts sound systems put in 200amp+ alternators…that can decrease gas mileage by as much as 4-5mpg…If in a 4=cylinder engine…maybe even more.

Not only the strain on the electrical components(I seen a Durango have it’s headlights flicker everytime the bass hit on the stereo), but the added weight of the speakers, speaker boxes, amps, etc. I’d hate to see what happened to that kid’s car on Pimp my Ride when they put that 250lbs speaker in the back of it. Hell, they had to take out the back seat just to fit it in there.