DIY lighting idea: Is this crazy?

J

jimbee

Member
So I was wondering, could I buy a car battery for $60, get a car headlight for $10, hang them off of a lightstand, connect the headlight to the battery with some regular electrical wire, put the headlight in a chinaball to diffuse it, and have a powerful no-outlet-required light?

Would I need some kind of voltage regulator to keep the headlight from burning out? Any "watts = volts X amps" advice much appreciated.

jimbee
 
i dont know about all the rest of things but it prolly would be better to just make a frame and stretch white cloth (rip stop nylon or thin bedsheet) and put that in from of the light instead of a china ball.
 
Regulator probably a good idea or the colour temperature will change as the battery discharges. On the topic of colour temperature, can you get any bulbs which are balanced correctly? 5500 K would be nice.
 
Automobile headlamps are DESIGNED to operate from ordinary lead-acid car batteries. They have been running that way (without any regulators) for almost 100 years (!)

The main problem with auto headlamps is that they have weird patterns. They are designed to illuminate the road ahead of you for driving at night, but not shine (too much) into the eyes of oncoming drivers.

There are many other 12V bulbs besides auto headlamps. I think the other kinds (vehicular, RV, and those designed for production lighting) would be better candidates for experimentation. Note that some common production bulbs are available in 12V versions and you can use them in the same fixtures that you would run on mains power (120V or 230V in Europe, etc.)
 
Richard Crowley said:
Automobile headlamps are DESIGNED to operate from ordinary lead-acid car batteries. They have been running that way (without any regulators) for almost 100 years (!)
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They aren't DESIGNED to hold a specific colour temperature during their operation, though, so I'd still recommend a steady voltage supply.
 
AndrewGentle said:
They aren't DESIGNED to hold a specific colour temperature during their operation, though, so I'd still recommend a steady voltage supply.
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It was the answer to the question "Would I need some kind of voltage regulator to keep the headlight from burning out?" Incandescent lamps in general suffer from the dimming vs. color temperature shift problem. Nothing new here.

Auto headlamps are just too weird to be worth voltage/power regulation to fix any color temperature issue. At least IMHO.
 
Thanks much for the advice. Yeah, I did not think about the weird pattern that a headlight would cast. Richard's suggestion of a different bulb sounds like a much better idea.
 
Low voltage and high current mean HEAVY cable if you don't want volt drop - and even quite chunky cable will significantly dim the lamp with a fairly short bit of cable. The other thing is that you really need what here in the UK is called a leisure battery - they're designed for continuous high(ish) output, whereas modern car batteries are designed to cope with hundreds of amps for very short periods, turning the engine over.

I bought a couple of car batteries to power some small hidden 12V birdies in a piece of scenery, and the auto accessory shop told me if I used them as I explained, then the warranty would be void. It seems as vehicle technology has got better, car batteries have got smaller, while still having high current capability - they're just not designed to run lower current for a longer period any longer. The Amp/hour rating doesn't seem to work.

They were actually right - a 50W pair of lamps turned on for just ten minutes managed to flatten the batteries, requiring charging between every show. Ten minutes at just over 8 amps shouldn't have taxed these batteries at all, based on the A/H rating, but it did!
 
i made test with HID car light. These are high voltage bulbs, usually sold as a pair with ballast. since HID is also available in movie industry, i think it could be an interesting solution.
You can choose them in many color (temp) from 3000 to 10000 K.
I choose them because they are supposed to offer better output, steady color.
the only drawback is they need more care (switching on/off require some caution) and lifetime is probably shorter that plain bulbs.
I had no occasion to really test them, but light is pretty powerfull, while mine are really high in temp, and the CRI seems very low.
I would not recommend a car battery since this kind of battery is not really designed to be drained very low. If you just plan to use it once or two, it should be ok, but for regular use, choose another type of battery.
My plan was to build a caddy with a big battery (around 300Amp/H) with china balls. finally i go to fluo bulbs that are delivery pretty big amount of light without much electric current (a 80W fluo bulb is equivalent to a 300W filament bulb and with a nicer color).
you can easily find 12-->110v converter for low power (less than 400W).
so a 400w converter still gives you enough power for 4x80W bulbs that is an equivalent to 1200W of light. something you will not get even with HID bulbs.
 
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