Headlights on.

Mpg loss would be negligible. I would think you won't even see a difference.


Yes, bulb replacement would be more frequent. Especially since you'd be subjecting the bulbs to any current spikes and fluctuations during startup.

 

Well, you would be if there were any. All the charging of the 12 volt system comes from a DC to DC converter, making 201 volts into 14.4 volts. No alternator, no starter motor, no big draws of any sort during start up, nor any fluctuation due to changes in RPM. Some folks report being able to start the Prius with two 9 volt transistor batteries.

The Bulbs will get hot and then cool down once the car is turned off, the drivers door opens, and the timer counts down. (I set mine to a 0 second countdown, but I am a guy who parks in a garage. you may want a longer countdown before the lights go off) But I do not fear voltage fluctuations, certainly the scanguage II never detects any.

 

I had a relay go bad on me a while back that went hot in Ready mode on my DRL module.

I opened the bad relay up and there was carbon on the relay contacts, most likely from arcing across the contacts due to chattering from voltage fluctuations at startup.

I installed a delay relay that supplies power to the DRL relay after a few seconds, when any voltage fluctuations have subsided. Haven't had any problems with the replacement relay since.

Sent my SCH

There's been a few threads and posts about headlight bulbs going out prematurely. A common point is that the users were leaving the headlight switch in the On position.

S fro my SHI53

 

It's pretty insignificant, but depends on how fast you're moving, and what your fuel economy is (or in other words, what your fuel consumption is in gallons per hour, rather than gallons per mile). As a rough estimate, it would need to use about a gallon of gas for every 50 hours that the headlights are on to generate the power to run them. If you're on the highway, getting 50 mpg at 65 mph, this amounts to about a 1.5% hit (using 1 extra gallon over 3,250 miles), which wouldn't be noticeable.

 

1) Lights consume electrical power as Watts.
2) Every 746 Watts of electrical power is one Horsepower.
3a) Mechanical power comes from gasoline.
3b) Electrical power comes from MG-regeneration.
4) Battery RE-charge comes from engine (gasoline) or regenerative braking (electricity).
5) Ain't NOTHING for free!

 

hallelujah!
So this is why I installed low power consumption Philips Daylight 8 drl led lights on my 2010 Prius.

SM-N900V ? 2

 

The mpg cost of headlights has been discussed in several past threads. Using computations along the same lines as Macman408's post, I believe the consensus was somewhere between 0.5 and 1.0 mpg at highway speed, and somewhat more in city conditions.

While this is small, it is larger than the rounding margin that the 2010 Prius had to get an EPA rating of 50 instead of 49.

My swag is that your LED DRLs probably consume very roughly 90% less than the full headlights, a small but very real savings.

 

Agreed. And my nephew tells me that the Philips drl add +10 hp given how good they look. ;-)



SM-N900V ? 2