12v vs 120v for lighting

[chrisgerman1983]

I am sure this will be an easy question for someone to answer... What voltage is better for making light? are they equal? I have a 1000w inverter that I am installing in my van for running tools and charging my cordless batteries. It got me wondering if you could use the AC current to run fluorescent headlights or driving lights... my night vision is pretty poor so I have always had big huge fog lights on my vehicles... would the lower wattage be worth any gain in fuel economy?

[gone-ot]

WATTS is watts:

12V × 10A = 120W

120V × 1A = 120W

...but the 12V system will require MUCH heftier gauge wires to handle 10A as compared to only 1A for the 120V system.

[ksa8907]

Also, your alternator makes 3 phase a/c which runs through diodes to get d/c, then your inverter turns it back into a/c. Every change wastes energy.

[Ryland]

Other then the larger gauge wire to power lower voltage lights, I've heard that lower voltage lights produce more light per watt for the same reason, assuming that you are using incandescent bulbs.
you are going to have an easier time finding LED marker lights, trailer lights, and vehicle bulb replacements, CFL's are not going to hold up to the vibration of the road as well and they are not directional like LED's are, some LED's have a 180 degree beam spread while CFL's will be shining as much light at the vehicle as they shine away, good for lighting up a room bad for lighting the outside of a vehicle.
If you want lights inside your van you can get a lot of 12v LED's, or you can go to most any store that is selling light bulbs now and buy LED's as well, for head lights you might be best off with HID head lights, high power surge when they first turn on but they tend to be lower over all wattage, you might also look in to getting fog lights.
Either way, every time you convert energy from one form to another you get losses, your inverter has losses and you have to figure that in when comparing the line losses from lower voltage wiring for 12v bulbs, most smaller inverters like your 1kw one tend to be around 85 to 90% efficient and I suspect that you will see less then 5% loss in your 12v electrical system if you have good connections and proper sized wire for the draw.

[oil pan 4]

Over on wind-sun.com they always try to stick with DC lighting when possible.
Inverter losses wont help you.

[2000mc]

i think all fluorescent lights use a ballast anyway. google 12v fluorescent ballast

if you are coming out ahead, watts to lumens wise, i think it would be hard to not lose all your gained efficiency to aiming / focusing issues.

[2000mc]

easier solution that i've done myself, assuming you have 9006 low beam and 9005 high beam bulbs, is install phillips 9012 (low beam) and 9011 (high beam)

the bulbs are HIR, halogen infrared reflecting, i guess using the infrared light to help keep the filament hot increases their efficiency. they claim to use the same wattage, while being brighter.

they are just short of plug and play, you just have to trim one of the tabs on the bulb to fit in the same hole as the 9006/9005.

they are definitely brighter than standard bulbs, but i haven't actually measured their power consumption

from what ive read, a std 9006 bulb puts out 1000 lumens, while a 9012 pus out 1875 lumens. i think doubling the lumens of a light makes it appear 50% brighter, so a 9012 should appear about 1/3 brighter than a 9006, which would be inline with my experience with them.

[chrisgerman1983]

Thanks everyone! figured it would be an easy question for you guys