Sooo I got to digging in my closet and found these...
They were both powered by 4Ah lead acid 6V batteries that the electrolyte had dried up (yes, stuff was rattling around inside the battery cases). The light source is an H3 type incandescent lamp from a car, 55W for ther smaller one and 100W for the big one. Pretty simple inside with only a charging jack and the simple resistor based charging circuit. The reflector is the negative contact of the battery. I'm thinking of putting a Cree CXB3950 in the big one with 8 li-ions in series for power since the emitter needs around 40 volts and 3600 mah drive current. I'm not sure what I'll do for a driver or cooling yet, but definitely a boost driver. I'll do an xhp70.2 on the smaller one with a 2S2P li-ion. I'm probably going to use a normal flashlight driver for this one not the big boost- buck power supplies. Anyway, just thought I'd share. Germ free to give suggestions or ideas!
Cool. I thought Cree wad the only firm making these ultra powerful cobs. 90 cri for over 9000lm is pretty crazy. I saw that it’s the 4000k one you linked. The 5000k is much more powerful over 12000lm so comparable with the CXB3590, although at a higher drive current and lower cri.
Tried modding a halogen light to an led. It’s not impossible, just not worth it. the reflector isn’t really meant for you to just pop an xhp70 in there, and the thermal management to the body isn’t there usually. It can be done, but not worth it IMO. When it comes down to it, look up the model of halogen bulb the light used, and buy a quality version of that bulb with the highest wattage you want. More light, less work. Just my .02 from attempting the same thing one some similar pistol-grip spotlights. I wish I had better advice for you, because those lights are handy and seem like a good mod host at first, until you get into the project…
Yeh, the filament of the bulb is “raised into” the reflector, while an LED would just sit at the bottom.
You could drill out / shave off the pointy end of the reflector to let the LED sit higher, but as mentioned, it usually ain’t worth it.
Probably possible to shine a light into the reflector from a distance, in a steamy bathroom, and see where the focal point is. That should give you a rough idea how high you’d have to sit the LED.
Or if you got a “grain o’ wheat” bulb, light it up and feed it into the reflector, and move it around ’til you can see roughly where you’d get the best focus.
Thanks for the tip. I considered the led drop in H3 lamps and they’re wimpy, 1000lm max and high quality ones are $100+ I also considered HID. Although super cool, putting an arc discharge lamp in the big one probably won’t work optimally. Plus, the power requirements are a little bit tricky since they have bulky ballasts and ignitors, although they have gotten smaller. That may still be an option since cooling wouldn’t be as much of a concern as LED (or as much work).
As fr as the work involved… I’ve actually done swaps before (see other post of mine Something I Put Together!) with smaller lights, so I know it can be done, it’s just a lot of work and I know what I’m in for. Lots of hand made parts, hours on the bench, blood, sweat, and finagling. I estimate it takes 80+ hours of work with my limited tools (no 3d pinter, mill, lathe, cnc-anything) to finish one. My 100W took almost 9 months street to finish. I posted a couple of the ones I’ve done previously. I’m almost finished with nice smaller one with an xhp50.2.
That’s a great idea I hadn’t thought of before with the little bulbs! What I’ve done before is just some eyeball geometry and looks-good-enough engineering to make it work! I cut down the back of the reflector and hand-fit the emitter until I get the best focus. I know it won’t be perfect. I’ll probably forego the COB for the big one since I’d have to cut down the reflector so much and give the HID a shot. It’s not super expensive like the COB project, $40 USD vs. closer to $110 for the other one. If it doesn’t work then it’s not hard to move forward with the led.
Plus, a 55W H3 spits out… what?… 1500lm? A decent XHP35 could be pushed to that without breaking much of a sweat.
You got your choice of powering it now that the Pb-acid batteries are dead. Cheap/simple driver, even 1-mode, would control the LED. Done.
Probably got plastic reflectors, so no heat-help there.
But with a smaller area of the LED vs filament, you’ll get better focus, so just like the C8T vs C8A, you’ll get better throw even if total lumenage is less. So go easy on the LED to keep it cozy, and you’ll still have decent throw.
1500lm is about right, maybe less. The 35W HID steps that up to 4000-4500lm and even more for 55W HID. The CXB3590 is 13000lm at 130-135W for the good bins in 5000k. But more heat, needing high capacity li-ions and a driver.
I’m not concerned about heat too much since both reflectors are chrome plated steel, maybe 24 or 26 gauge? They have to be or that hot H3 would melt it. The big light had a 100W lamp in it. The reflector on that is enameled steel.
I’m researching HID. I did a 35W retrofit on my cars low beams 11 years ago and still on the same ballasts!
I’m still up in the air for the big one on lighting though. I want more power.
You’d be surprised. Back when I had an old Cavalier with four 4×6 headlight bulbs and a real bumper, I made the mistake of getting a set of PIAA driving lights.
PLASTIC reflector with a 55W bulb! Wtf?? They specifically warned about not putting a hotter bulb in there as to not melt the reflector, but apparently with 55W it was okay. I returned ’em as garbage. Only bought ’em because of the “brand name”, figuring they’d be decent quality. To this day, though, I remember that PIAA = crap.
My “cheap” and “crappy” lights I’d get from Harbor Freight or wherever, had real metal reflectors.
I meant feel free