Double filament means it's a dual usage bulb mainly used for the tail lights.
One filament is on during regular operation, but when you press on the brake, the second filament comes on to double the brightness.

If you notice that with the radio, the increase of volume, how do you know that the "battery came up" - did you check it with the VOM ? It's not battery voltage going up, but the voltage coming from the alternator. check voltage out of the cigarette lighter socket before and after this happen and see the results - bet you got a flaky alternator.

<_< either you don't know what your talking about, or you don't understand. Or you don't know what I'm talking about because you disregarded the link. The link is for head lamps for my pop up head lights. Since I have one set of head lights I have double filament light bulbs for high beam and low beam.

As for the battery the car was off. Not running. Only key in to let radio on and the cigarette outlet voltage reader said the voltage went up by .6

wolf alchemy said:

<_< either you don't know what your talking about, or you don't understand. Or you don't know what I'm talking about because you disregarded the link. The link is for head lamps for my pop up head lights. Since I have one set of head lights I have double filament light bulbs for high beam and low beam.

As for the battery the car was off. Not running. Only key in to let radio on and the cigarette outlet voltage reader said the voltage went up by .6

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Those head lights are just plastic housings with h4 halogen bulbs, as where the stocks are sealed glass halogen. The dual filament thing that you are talking about is just a bulb that has 2 filaments, one for the high beams, and one for the low beams. The stock lights are also dual filament. Some cars use a separate bulb for high beams and a separate for low beams, those and single filament. As for the voltage thing, i think you are just seeing something random that i don't know why you are even asking a question about.

Dual filament means it has the low and high beams are in one bulb, some cars have two headlights. But unless you have an amp and some big subs blasting, 10 min is too fast. Have it losd tested.

bryanwheat said:

Those head lights are just plastic housings with h4 halogen bulbs, as where the stocks are sealed glass halogen. The dual filament thing that you are talking about is just a bulb that has 2 filaments, one for the high beams, and one for the low beams. The stock lights are also dual filament. Some cars use a separate bulb for high beams and a separate for low beams, those and single filament. As for the voltage thing, i think you are just seeing something random that i don't know why you are even asking a question about.

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Yes! That is exactly correct and on the same page as me. Sorry if I seemed rude, but I was annoyed that dsm1g90 most likely didn't look\read the link. As to them being plastic does that mean I should skip on them?[DOUBLEPOST=1411280382][/DOUBLEPOST]

mercaholik said:

Dual filament means it has the low and high beams are in one bulb, some cars have two headlights. But unless you have an amp and some big subs blasting, 10 min is too fast. Have it losd tested.

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Well I do have a 200 watt amp and I did have it on. But turned it off to conserve battery power