Headlights Question

<div class='quotetop'>QUOTE(prius2006rocks @ Oct 21 2007, 10:00 PM) [snapback]528684[/snapback]</div>

There is an Auto off feature, leave your lights on and they will turn off when the drivers door is opened after car is shut down. There is not an DRL feature in the US version, only Canada got that feature on this continent.

 

Non-U.S. versions have the auto-on headlight feature. Why we don't in the U.S. has been the subject of much speculation. There is a spot on the top of the dash for the sensor. Even my 1994 Ford Aerostar came with it.

Tom

 

Only get the switches themselves off when the door opens after power down here in Australia, not light sensing headlights. Commodores have that feature but they don't have HSD or a Toyota badge.

 

HID lights and auto-on are mutually exclusive. running HIDs as running lights in a toyota is a surefire recipe for early replacement for those expensive bulbs.

 

<div class='quotetop'>QUOTE(galaxee @ Oct 22 2007, 11:19 PM) [snapback]529138[/snapback]</div>

Running lights and auto-on are not the same thing, as I'm sure you know. I believe the OP is talking about headlamps that automatically turn on at night when needed, not headlamps that stay on all the time when driving. An auto-on feature should be no harder on expensive headlamps than running them by hand.

Tom

 

<div class='quotetop'>QUOTE(galaxee @ Oct 22 2007, 07:19 PM) [snapback]529138[/snapback]</div>

One random data point: I've a 2005 with HID headlamps, and I run them 100% of the time (I believe that DRL are a great safety idea). 43k miles, 30 months, and still on the original factory lamps.

(Of course, I likely just jinxed myself...)

 

<div class='quotetop'>QUOTE(Tideland Prius @ Oct 23 2007, 11:40 PM) [snapback]529543[/snapback]</div>

Only if they are poorly designed. With proper thresholds and hysteresis, auto headlights will work as well or better than manual control.

Tom

 

On my 2006 I kept the HID's on all the time - after changing the left one at 30K and the right at 35K (both changes under warranty ) I wised up and use them only during night drive.

Keeping the HID's on for an average of 32.5 Kmiles and an average speed of 50 mph (fwy & city) calculates to
650 hours which is a pretty accurate life expectancy of a Xenon arc lamp.

There are a number of factors that affect the life of a Xenon lamp, most important are: cooling and DC supply ripple followed by the number of ignition cycles.

In a car there is one more factor: mechanical vibration that may result in a slow leak of the Xenon gas.

At least with the gas discharge lamps you get some warning that they are about to die in contrast to filament lamps (including halogens) that they just do.

my 10c worth -

 

ah- i did mean DRLs. as for auto, i don't know why we don't have that here.

the only HIDs that DH ever saw burnt out were used 100% of the time the vehicle was on.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Oct 24 2007, 11:10 AM) [snapback]529687[/snapback]</div>

Agreed. It takes a high voltage to strike a gas discharge lamp, and it is definitely bad for them to short cycle on and off. I still don't see where this fits into the auto-headlamp discussion. Let's back up a bit and see if we are on the same page, or perhaps we are discussing two different issues:

I believe the OP originally asked why the Prius in the U.S. doesn't have auto-headlights. By auto-headlights I assumed the OP meant headlamps that automatically turn on when it gets dark outside and automatically turn off when it gets light. This is a common feature that has been on many automobile models for more than a decade. The only difference between automatically controlling conventional headlamps and HID headlamps is the need to avoid short-cycling the HID lamps, which can easily be accomplished by proper use of hysteresis and timing delays, especially with a car as smart as the Prius. It's not a difficult task.

That brings me around to the original question: Why no auto-headlamps for the U.S. version of the Prius? It's not a big issue for me, just more of a curious question.

Tom

 

Daylight running lights are typically the high beams off of incandescent (old style filament) headlights. They run them at reduced voltage to reduce brightness, but use the high beams to make sure the pattern is pointing at oncoming drivers. Obviously this wouldn't work in HID lights, you can't run them at reduced voltage.
For some HID cars they add an additional low wattage incandescent bulb in the fixture, or on cars with retractable headlights they will put a brighter bulb in the turn signal or marker light fixture. In any case to include DRL on a car with HID you have to add an extra set of bulbs. I guess Toyota thought it wasn't of enough value to the consumer to add them. Personally I agree.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Oct 24 2007, 03:34 PM) [snapback]529819[/snapback]</div>

That's from a poorly designed auto headlight controller. There is no way it should respond fast enough to cycle going though tree shadows. Stopping under cover is a tougher issue. Heuristics can be used to deal with some of these situations, but you can always think of special cases where the controller will turn on the lights (total solar eclipse while driving to work...). An argument can be made that the lights should be on if it's dark enough to cause them to come on, such as in a garage or solar eclipse (assuming the controller isn't overly zealous). Even if you discount this argument, auto headlight controllers can always be turned off if the user finds they don't work well for a particular driving situation. For most of us they work just fine.

Tom