Headlights burning out

Measure your 12V bus while the Prius is in ready. It should be around 13.8V. If you see much above this, it could be high voltage leading to early bulb failure.

It's more likely that you got some bad bulbs, or drive with them on all of the time.

Tom

 

1. How many miles per year do you drive, and how many hours of run time does that translate to?

2. Do you drive on less-than-smooth roads?

3. When replacing the bulbs, do you use something to hold the glass so that your skin oil does not get onto the bulb surface?

4. What bulb brand do you buy?

 

As Patrick implies, DO NOT touch a halogen bulb. If you do you must clean it (degreaser) before using it. If you don't the quartz will overheat and fail.

With halogen bulbs, -low voltage-, not high will shorten their life. They need to be hot to recombine the tungsten halide that forms in the envelope. This is why they work at all. They run a small volume in the envelope, thus causing the envelope to run hot - thus requiring it to be quartz. They put a halogen in the envelope to combine with the tungsten that is evaporated off the filament due to the higher temperature they run at (the higher temp gives more light). At the highest temp spot on the filament (where the filament is thinning due to evaporation) the tungsten halide is broken down back to tungsten, which sticks to the filament, and halogen gas which is then reused in the envelope somewhere else.

So, check your voltage -at the bulb-. You may have a loose connection at the fuse causing a small voltage drop.

 

FYI, and as a point of reference, Philips says that the typical OEM halogen bulbs last around 500 hours (that's around 25,000 miles if you leave your bulbs on all the time while driving, and average 50 mph).

Also, I understand that halogen bulbs gradually get dimmer. So you might want to change them every couple of years even before they burn out.

 

Osram Sylvania recommends replacing halogen bulbs once per year:
OSRAM SYLVANIA - Frequently Asked Questions

Of course it is in their interest to do so.

My 2004 w/HID has 111K miles and the original bulbs are still in place. My 2007 w/halogen bulbs has 26K miles and original bulbs. I do not use the headlights except at nighttime.

 

Pearl still has the original bulbs, at 55,000 km. They run all the time, mostly in DRL mode (dimmed). This probably works because they run so cool that the tungsten doesn't evaporate off the filament. In fact, my last three vehicles have used H4 halogen bulbs, and I've kept each for over 100,000 km. I've never burnt out an H4 bulb. Of course just typing that will doom me now.

 

Check the -ve cable attachment for the 12V battery to the vehicle body. Some of them get loose and can cause the voltage to fluctuate.

 

Have the same issue with wife's 05 prius. Goes thru headlights about every 6-8 months. The sylvania bulbs were under warranty so contacted their warranty people. they send me bulbs for free when I email them my receipts from autozone. Been thru about 3 pair of headlights in the last couple of years but sylvania keeps sending replacements...but you are right, something ain't right with these headlights..

 

I've been holding off saying it BUT if the voltage is correct STOP using Sylvania bulbs! Get real ones.

 

Bosch and Hella make them. Then there are the Japanese ones and Chinese ones. Though I suspect the Sylvania are Chinese. The problem with Sylvania is they are designed to appear brighter. Which means they will not last as long.

You can get Hella bulbs of higher power than stock. They are, of course, illegal (legal bulbs will run 55W low beam and 65W high beam). Not sure how anyone would catch you with them, as you would have to remove them to check the power rating. You can get 65W low beam, 75W, 85W, and I've even seen 100W, all in the H4 size. Higher power bulbs might strain the electrical system (wires and fuses) and could overheat the housings, causing the plastic to melt. In the interest of full disclosure.

For example try Daniel Stern Lighting Consultancy and Supply

A simple search on google for H4 halogen bulbs gave me that link.

 

If your voltage is below 14, and you are absolutely not touching the quartz (glass) when you install, then something else is going on. I would definitely try another brand!

The only other possibility I can imagine is are you driving on rough roads? (high vibration)

 

Have you tried using something other than the latex gloves to prevent contact with the quartz? I usually handle them with a paper towel and haven't had any problems.

Is it possible that the bulbs aren't seating properly when you install them? I recall taking quite a while to get the bulb "just so" last time I replaced a set. Alternatively, is it possible that you are scratching the quartz when you install the bulb? I think any defect would threaten its integrity, and it takes a heroic effort to get the bulb in there without making contact with anything.