Headlights dimming, just when i turn on my fogs Options

[goferris]

something i noticed on my car last night when i was driving. if i just have my headlights on it seems that they are brighter than when i have both them and my oem fogs on. has anyone else noticed that on their car? is there a relay or something that would cause that or do i just have a weak battery? nothing serious just something i would ask about.
also what is the bulb # on the silverstars for the lowbeams?
thanks guys

[K-ESD]

the best way to tell if your alt. is on the way is when idling and you rev, your lights go brighter.

you can measure the running voltage of your alt. with a voltmeter, it should read 13.9V to 15.1V when engine is cold and 13.5V to 14.3V when hot. You can also measure the drop when you turn on your fog lights.

Another thing, how did you wire up your fog lights? If you use the headlight wire for power, this would be the reason why everything is going dim. That little wire can't handle the draw and causes a voltage drop when high current is trying to pass thru.