Daytime Lights

[NimbleYarisOwner]

Hello Everyone,
Being cheap, I want to improve fuel economy by eliminating the daytime
running headlights.

They are dangerous for me because at night I think i have
my headlights on when really its only the daytime running headlights.
So there is no rear lights at all.

Has anybody done that?

Thanks!

[nqd]

hey welcome to the boards....

a bunch of us have already done this...


here is a link to how

http://www.yarisworld.com/forums/sho...ht=disable+drl

[Thirty-Nine]

Originally Posted by CheapYarisOwner

Hello Everyone,
Being cheap, I want to improve fuel economy by eliminating the daytime
running headlights.

I can't imagine you'd bet much better milage because your lights aren't on. Please correct me if I'm wrong, though.

[Edd]

True, it shouldn't be significant unless you've got exceptionally high wattage DRLs.

[alhope34]

Originally Posted by CheapYarisOwner

They are dangerous for me because at night I think i have
my headlights on when really its only the daytime running headlights.
So there is no rear lights at all.

Has anybody done that?

No, I haven't, not once in my life. I always remember to turn the lights on at night.

[churp]

Just remember the other lights (heater/ventilation/etc.), if they're not on your tailights aren't on either!!!

[NimbleYarisOwner]

Currently I average about 34-35 mpg.
I will see what the impact is of not having DRL's.
There must be a MPG impact because you can't get free energy as fas as i know.

I still think they are dangerous because they are too bright and I recieved a ticket.

[Thirty-Nine]

You received at ticket for your DRLs? I hope you faught that.

[Black Yaris]

noobs......

[BailOut]

You're not going to notice any FE improvement without DRLs as the gain will be microscopic.

Our headlights run at 60W in DRL mode, and 55W in "night mode". 60W * 2 headlights = 120W.

12V * nA =120W
n = 10A

Our alternator is rated at 60A, and "idles" around 20A, so the DRL are using half of the idle load. The stock stereo uses another couple of amps, and so does the ventilation fan.

In other words you can have the DRL, the fan on setting 2 or 3, the stock stereo on at mid-volume and have a map light going without the alternator placing any additional load on the engine. However, if you have a large after-market audio setup, or if you drive like a maniac and place a lot of load on the engine, you have much less of the alternator's idle output to play with, if any.

[sherryberry]

yay for bailout! always got the answer when it pertains to fuel economy. i'd only get rid of DRL because they're so bright.

[bearda]

Originally Posted by BailOut

Our headlights run at 60W in DRL mode, and 55W in "night mode". 60W * 2 headlights = 120W.
.

Wait, the headlights draw more power during the day? I've always heard of it operating the other way around, with the DRLs running with reduced output.

[BailOut]

Well, bearda, we're both wrong. After looking at the wiring and lighting diagrams again I see that both DRL and regular headlight usage are 55W while the brights are 60W.

This is actually good news as it means the DRL use 10W less than I originally calculated, meaning around a 9A load on the alternator rather than a 10A load.

[adamschneider]

Seems to me that if the front headlights are running at the same wattage in "day" or "night" mode (which is absolutely freakin' bizarre!), you're still using a little more power at night because of all the other lights (tail lights, running lights, etc.), correct?

I thought I noticed, by the way, that in "night" mode some other little bulb lit up in there...

[NimbleYarisOwner]

OK so 55W*2=110 watts
with ~30% engine efficiency thats 366 watts or approx. 1/2 hp.
from there you can figure out your gas quantity to make that power.

[BailOut]

Originally Posted by adamschneider

I thought I noticed, by the way, that in "night" mode some other little bulb lit up in there...

I thought the same thing but discovered it's just the running/position light nearest the headlight lamp that adds to the lighting effect.

[BailOut]

Originally Posted by NimbleYarisOwner

OK so 55W*2=110 watts
with ~30% engine efficiency thats 366 watts or approx. 1/2 hp.
from there you can figure out your gas quantity to make that power.

The engine's efficiency doesn't apply here as the alternator is capable of producing 20A while in its "idle" state. The only way you could make the alternator drag less would be to remove it from the vehicle. The 30% rule would only come in if you are drawing more than that 20A.

20A * 12V = 240W, so you have 240W to play with before the alternator clutches and really starts creating drag.

[bearda]

So it's 1/2 hp in the worst case, when the rest of the devices on the vehicle are collectively pulling 20A or more and the alternator is going to drag down an additional amount based on the DRL draw, right?

So you're looking at about around a .5 % increase in efficiency if you;'re constantly dragging down the alternator. Keep the DRL, the extra visibility is worth it.