[waterboarder]

Well, last night it got down to -4˚F. This morning when I went out to the Jeep, it had warmed up to 0˚F. Unfortunately, when I turned the headlights on (Cibie, Osram bulbs, Daniel Stern Lighting harness), they came on for just a fraction of a second and then turned off. I didn't have time to deal with it before work, so I had to drive to work with no headlights and used my aux lights - hoping no police would see me.

I dunno if this is a cold weather thing, or if it is just coincidence. I don't know if it is the bulbs themselves, the relay or a fuse. Since both bulbs went out, I'm thinking it is probably a fuse, or maybe a relay. I'm hoping it is a fuse. I guess I will find out after work today when I have a chance to deal with it ):

As anyone else seen something similar with their headlights and cold weather?

[waterboarder]

Summary Of Issue:
Overnight low of -4˚F (-20˚C). In the morning, I used the remote start to start the vehicle and let it warm up for 15 minutes (and then it auto shutdown). Then I went out and started it up and turned on the lights. The low-beams came on for just a microsecond and then turned off. High beams still functional. I can only guess the low beams died due to cold temperature.

Osram 70/65 bulbs ($22 x 2 = $44)
Installed: 9/15/2009 @ 30,990 mi
Died: 11/17/2009 @ 32,855 mi (low beams died, presumably due to cold)
Service life: 2 months, 2 days or 1865 miles.
Conclusion:
These bulbs are way too expensive to be going out after such a short service life. It isn't even really COLD yet. We easily get temps to -20˚F (-29˚C) in my local area, and sometimes colder. If I drive to Fairbanks, it can easily hit -50˚F (-46˚C). I've never had this kind of problem before with cold temperatures and bulbs - so I don't think my expectations are unrealistic. I've done some checking around and it seems other people are having cold weather performance problems with these bulbs too. And no, I did NOT touch the bulbs and make them burn out early.

Solution:
OK, so today I had some daylight and some time, so I was able to work on my headlight problem. I did it in my driveway, and the temp was 10˚F (-12˚C), and it took a total of 45 minutes (excluding time sourcing replacement bulbs), so I was a bit on the cold side by the time I got done (:

I found some bulbs at NAPA cheaper than anywhere else in town, so I thought I would give them a try. First, I tried Wagner H4 bulbs (BP1210/H4). These did not work properly. They worked only on low-beam, but not on high-beam. They are sold as "off-road only" but I thought they would still have two filaments in them.....but I guess not. Fortunately, NAPA gave me my $25 back on these.

Then I tried Wagner H4 bulbs (BP1260/H4). These are sold as 60/55w DOT approved bulbs. They did work properly, on high and low beam. The pair cost just under $20 (compare with $44+shipping for the Osram bulbs). As it is not yet night time, I have not been able to judge their performance with respect to lighting up the road. Given the lower wattage and off-brand nature of these bulbs, my expectations are pretty low. Even so - I am hoping they will last a lot longer than the Osram bulbs. I guess we shall see (:

[waterboarder]

I've been having some e-mail exchange with Stern on my issue. He has given me permission to post it here. I'm doing so because it is very informative, shows his level of support, and thought some of you might find it interesting. So, here it is.

Message #1:
I intend to send you some new bulbs (different ones that I suspect may better resist the elevated voltage caused by the temperature-compensation subfunction of the voltage regulation function of the vehicle's powertrain control module), and I have in mind the addition of a couple of power capacitors to the harness to attenuate the voltage spikes that are likely responsible for the short bulb life.

Message #2:
It's not that cold weather affects the bulbs per se. They do not know or care what the ambient temperature is. It's that the voltage regulator in this vehicle (as in many other Chrysler products for many years) has a temperature-compensation function that's aggressive at the cold end, raising line voltage unnecessarily and tending to introduce transient spikes, which hammer the bulbs hard. Temperature compensation is necessary, because cold batteries have higher internal resistance so charging voltage must be higher, but not quite so high as is the case in the JK, and never with spikes. Nothing can be done to fix the cause; all we can do is see about addressing the symptom. As I say, let's see if some of the bulbs I send you will be more resistant. I need to do some calculation on the capacitor value; don't send back your harness just yet.

[waterboarder]

Well, today I received a new harness from Daniel Stern (via Susquehanna motorsports), at no charge (replace under warranty). This new harness has two extra capacitors in it. I believe the theory is that this will help isolate the bulbs from a voltage spike caused by higher-than-normal voltage output during cold weather conditions, when the system is initialized at power-on. This should prevent shock to the filaments inside the bulbs and help them last longer in the cold.

So - Stern comes through. His service is top notch. Once again, highly recommend.

[DanZ51]

Very interesting!

I wonder how long these "aggressive temperature-compensation functions (transient spikes) last after starting, seconds, minutes, til the battery warms up?