# Thread: Car Low Beam Halogen Flashlight

1. ## Car Low Beam Halogen Flashlight

I know nothing about building or modifying lights, I'm sure this will be painfully obvious in the next sentence. Can you drive a low beam halogen lamp [from a car] with 4xCR123's?

If the answer is yes, about how long would one battery set last? Has anybody built such a light?

TIA

2. ## Re: Car Low Beam Halogen Flashlight

Most likely...but the runtime will be very, very short. (probably a couple minutes)

3. ## Re: Car Low Beam Halogen Flashlight

If you really want to make something slick, try your hand at a HID arc flashlight. Those are the spiffy new ones coming on the top-of-the-line luxury cars. Not only do they run on low voltages (because they need a step-up circuit anyway) and are obviously VERY bright, but they also happen to be very efficient! A set of D cells running one of those lights would likely last several hours. Lumens per watt is way more than Luxeon.

4. ## Re: Car Low Beam Halogen Flashlight

A halogen car low beam is usually about 55 Watts/12V (H4, H3 etc). That results in a current of more than 4 Amps (!), and I dont think 4 CR123s is able to give you 12V at that current. You probably have to use 5 CR123s or connect 8 ones using a parallell/serial configuration to get high enough voltage.

For comparison: The Surefire 500 lm N62 lamp is using 4 CR123s with a current of 3.7 amps. At that current the batt voltage is below 8V. (Source: Brocks flashlight site - look at the top of the table at the bottom of the page).

Bjorn

5. ## Re: Car Low Beam Halogen Flashlight

Did I read someplace that there is a limit to the number 123 you could use in series [safely]?

If MN21 can suck 4.7 amps at 6.1 volts for 20 minutes with 3x2 configuration, then would it be safe to say that a 3x4 configuration could support 4 amps at 12 volts for about the same length of time?

Does anyone know the lumens rating for an H4?

6. ## Re: Car Low Beam Halogen Flashlight

[ QUOTE ]

Does anyone know the lumens rating for an H4?

[/ QUOTE ]
Yes. http://www.lighting.philips.com/nam/.../mini_seal.pdf

1000lm low, 1650lm high.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•