2008 Elantra GLS.

Lost a drivers side low beam lamp about 3 weeks ago and replaced it. Yesterday it burned out. Replaced it again last night and after about 30 seconds it blew the fuse. Took that bulb and tried it on the passenger side and it blew that fuse too.

Thought maybe voltage regulator is bad. Checked charging voltage and it was 14.7 volts across the battery.

H11b bulbs from Orielly and NAPA.

Anyone have any ideas?

 

Dude,
From what you have presented here, you might have purchased a bad bulb. I have
not seen this type of problem in the past, however, there is always a first. Keeping it
simple, a bulb failure is not too rare. Bad bulbs that have an internal short are a rarity.
With good regulated voltage, and the problem following the bulb, my put would be to
get the bulb in question to Orielly's and ask them to "Ohm" the connections to see
how much internal resistance you have. I don't have any values to give you as I have
not chased this problem in the past. You may want to "Ohm" the contacts of your
good bulb to get some sort of baseline value for yourself too.
On a previous post, I had a problem with a dual element bulb that had an internal short
and when I applied the brakes, the dash lit up. When I turned on the lights, the brake
lights lit up. The the bulb filaments were touching internally, thus shorting the circuits
together, quite perplexing, as previous experience with bulbs dealt with "Burned Out"
or open filament conditions. SBR711 had an idea to check the indexing of the bulbs
and that drove me to verify whether or not a bulb had been improperly installed,
which might cause my condition. The first bulb inspected, left rear tail lamp was the
culprit, the internal filaments were touching! See attachment for actual bulb. So
the moral of this story is "You can expect the unexpected" with bulbs and electrons.

If you are lucky, you might have just tripped over a faulty "New" bulb.

Happy Easter and good luck.