Building a hand-held 3KW HID short-arc spotlight.

Ok.. i totally 'got the bug'.. i played with a maxabeam and it is just waaayy tooo much fun. I recalled aquiring a 3000W arc lamp bulb used for movie projection a while back... and sourced the reflector and bulb socket..

What i need is a power supply.. an igniter and a container with some SERIOUS cooling.

From what my research so far has shown.. the lamp is happiest on pure DC between 24 and 30V.. I have a feeling that i could achieve a near constant current from the painfully easy solution of a number of lead-acid cells in series.. of course very large ones since the bulb runs on 80 to 100A.

i have the technology to make the igniter if i have to.. i have to find out the voltage requirements of the ignition, and it would be great to find out the specs exactly are but i'm pretty sure that it's just pure DC and LOTS of it once it starts.. i know it uses a very powerful magnet to stabilize the arc but i have that covered also.

anybody make something like this on CPF?.. i'm normally in the 'tiny and bright' business, but something is somewhat awe-inspiring about 80,000 lumens in an 18" reflector.. if i had to bet.. it would be able to produce on the order of 50 lumens at 1 mile.

oh.. the nickname right now is 'oscarbeam' because the only suitable pre-fab container i could find to build it into was a galvanized trash can..

safety considerations include UV-filter glass.. and 1/4" plate glass lens.. tortuurous path for the massive air-flow required to cool 3000W.. so there would be no chance to directly view the bulb.

In any event.. the bulb alone is probably worth $800.. cost me zero, so i want to put it to CPF good use.. is there a record out there for how many lumens in a portable light?

-awr

Re: Tyring to build a 3KW spotlight.

Sounds very interesting. Some have talked about building such a light, but no one to my knowledge ever completed one. The Searchlight on Ebay Here talked about in a different thread looks very tempting. Have you ever thought about a small get together from the Southern WI. and Northern IL. area ?
Larry.

Re: Tyring to build a 3KW spotlight.

The Maxabeam guy was selling a 1000 watt vehicle mounted HID spotlight for around $1K. Sounds awesome. I made some inquiries about a passaround (e.g. a dozen CPF'ers chip in and buy it, pass it around, and then maybe put it on ebay after everyone has gotten to play with it) but nobody else was interested.

Re: Tyring to build a 3KW spotlight.

I saw "ignitor" and thought "power supply"... here are some pics of my 4000w lights and their counterparts. /ubbthreads/images/graemlins/grin.gif

Power supplies for a 4-head searchlight


Light head assembly, with reflector. The positive jaw connector was off at the moment.


BEAMSHOT I! (Nearfield)


BEAMSHOT II! (Prettier, farfield)

Re: Tyring to build a 3KW spotlight.

Now that's what I call a light! /ubbthreads/images/graemlins/smile.gif

Mark

Re: Tyring to build a 3KW spotlight.

larryk.. thanks for the link.. that light is basically the exact bulb i have.. interesting design, very compact... 250M lux.. pretty astounding but in the ball park of my calculations.. 80,000lux bulb is what we are estimating.

DJMT.. do you have any wiring diagrams.. parts lists, etc? I'm trying to make mind run off of only batteries.. i have to find out what the voltage on the spark is so i can create the ignitor if i can't find one.. i believe i can make an appropriate sparker from an ignition coil of a car, actually.. they can make up to 50KV if needed.. i think i need in the neighborhood of 6KV.. piecea cake for an ignition coil... i can even use the points and condenser as the 'start' button.

I've found a couple 12V batts that could run 1900W for about 10 minutes.. and small enough to carry in a backpack.. but i'd like to find (5) 6V batts that can handle 100A.. may have to tote on a hand truck but that's portable enough to take places.. I also need to figure out how to drop 3V, but plan on just using a long enough cord.. 27V will get me abou 100A and 2700W.. almost identical to the specs on that military spot..

I am almost postitive that pure DC from a battery will run the bulb if i can ignite it.. i think the nature of the internal resistance will work to establish a constant current.. (i.e. when current drops.. V will rise and vice-versa).. large lead-acid batts tend to have pretty stable voltage.

are those bigarse capacitors in there under the lights? It looks like you have a system with a gas-powered generator, feeds into some big banks of rectifiers and the DC is fed to the lights.... a big cap on each light would help keep the load stable and reduce feed ripple.. but with pure DC from a bat i shouldn't need any of that.

Very cool spotlight, almost exactly what i'm trying to make.. my reflector looks very similar.. but without the internal can around the light.

-awr

Re: Tyring to build a 3KW spotlight.

See what trouble happens when you loan out a Maxabeam- This guy wants to Illuminate er is that illiminate his neighborhood? Being the poor uninformed EE that I am I might have to "Help" him. Then I can try it in my backyard!
Now that IS the Arc the will RULE the dark! We can use the Maxabeam as a "Spotter beam" to pre-aim Photon torpedoes. Then -Fuff-"On" go the lights. Stand by, Racine ,Wisconsin. I wonder how much a disturbing the peace ticket is? And hey-Andrew- No WAGONS! I am stronger than I look and should be able to "Pack it" It has to be hand held to qualify as a "FlashLight" Go run and hide, Sleaper.... /ubbthreads/images/graemlins/wink.gif
1 Back pack with 5 6 volt SLA's may cut it for a short run.
3 medium SLA 12 volt cells would probably dip to 9 volts with 100 amp load..... /ubbthreads/images/graemlins/help.gif

Re: Tyring to build a 3KW spotlight.

i've found some nice panasonic batteries that will output 100+A but they are 'too good' the voltage still is like 11.5V under load.. I need a crappier battery ;-).. i'll have to have a look-see for those 300W .5ohm resistors i saw out in the garage days gone by.

-awr

Re: Tyring to build a 3KW spotlight.

I have a 1,600Ah battery bank for my 12-volt solar system. That's about 1,000 pounds of batteries. My deep-well pump draws 120 amps (at 12VDC). And even with a new, fully charged battery bank that size, the voltage will drop from 12.7V to 12.1 volts in about 20 seconds. With a smaller battery bank--one you could carry--I'd expect the voltage to drop extremely fast at 100 amps and the light would dim quickly.

Re: Tyring to build a 3KW spotlight.

If you're looking at having the light portable in a wheeled fashion, would you not maybe be as well looing into getting a secondhand petrol generator and running the lamp through a variac/rectification system? Finding batts capable of dealing with that sort of current is gonna be tricky, plus as I recall, those lamps are pretty sensitive to how they're driven. Underdriving is probably as bad as overdriving - which would start to happen as the batteries discharge, which they will - rapidly.

I'd certainly be thinking about a generator and a purpose built power supply. Running one of these lamps off batteries is not something I'd like to try. Too much margin for error I think.

Re: Tyring to build a 3KW spotlight.

Batteries have gotten a lot better. They now have 28 volt 100 amp Li-ions cheap. And only 1.5 Kilo!

Re: Tyring to build a 3KW spotlight.

this particular light is meant for 10-20 seconds at a time... NikolaTesla is the other principal working on this project and we have solve most of the problems.

NT found the 28Vx100A batteries.. he thought it was a single cell but turned out to be 7 in series.. nonetheless.. a battery pack you can hold in your hand.. that has 84WH or power and is like 3pounds..

We had been planning on making a 'backpack' battery to operate the light.. still might if we want to have longer runtime.. but this light is a 'technology demonstrator' more than a practical long-term search light.. i.e. not for use to locate a guy who fell in the sea.. although i'm working on putting in a connector jack that i could run it from a 28V aircraft generator.. i can pull 100A out of one of those.. so it could be adapted to a boat/car/plane use.

I designed a wattmeter and will have watts.. amps.. volts continously displayed.. you are correct that they do not like to be underdriven.. and it will only take about 3-4 minutes to deplete the cells we currently plan on using... there will be an additional battery to run the electronics and the FAAAANNN... the specs for the bulb are 1500cfm to keep it cool. so.. basically i need to run a car blower motor across the bulb to keep the thing cool.. so we are going to have a 12V battery in the design as well.

fortunately.. i can get 'spent' bulbs from a movie theater so i can practice on some end of life bulbs before breaking my brand new one.. i think they cost like $800 new or something but i got one for free which is what started this whole ball of wax.. not to mention N.T. lending me a maxabeam.

In any event... this will be force to be reckoned with if we can pull it off.. odds i'd put at over 90% now.

-awr

Re: Building a 3KW handheld spotlight.

the odds keep climbing.. NT did a test with a bulb and a sparker.. and we've sourced the inductor.. the batteries.. the wires.. the reflector.. we did a fun little test with the reflector using the lioncub with the head removed.. the reflector is a little smaller i think than i'd orginally thought so the size might be considerably smaller.. might be able to build it into one of those chrome 'bullet' kitchen garbage cans..

Re: Building a 3KW handheld spotlight.

I found a battery analyzer rated for 60V and 100A... so one more part down.... i was going to build separate displays for amps, volts, watts.. but might just use this one.. jury still out.

-awr

Re: Tyring to build a 3KW spotlight.

you should edit the title of this thread
Tyring to build a 3KW hid spotlight.

very kool I wish you the best

Re: Building a 3KW handheld spotlight

i was under the impression that HID was high-voltage .. this is strictly and arc-lamp.. 27V or so pure DC.. we are pretty much past the 'trying' stage and into building which is why i changed the title.. of course the original typo when i first started the thread keeps haunting me.

My goal and i won't be happy if not achieved.. have it fully operational before laborday. Well find out what kind of light-producing ordinances i'll break sometime i'm sure.

-awr

Re: Building a 3KW handheld spotlight

d2s 35 watt hid is about 1/2 amp at 85 volts

27 volts at 3kw seems like a high intensity discharge to me.

Re: Building a 3KW handheld spotlight

There is a key difference i've just found out... HID bulbs have halide salts in that bump the efficiency way up... an HID bulb can output over 100 lumens/W... where the arc lamp like the oscarbeam will 'only' output about 40 lumens per watt.

Oh it'll be high intensity.. but i don't think it's considered in the 'group' of HID on that technicality.. low efficiency... Batteries came in today... holy cow they are awesome.. only ran them on with the tool they came with ... sawzall... it's insane.. absolutely no difference from a corded tool... it's a good sign.

-awr

Re: Building a 3KW handheld spotlight

Xenon short-arc bulbs are still HIDs. In fact they could be considered more of a "true HID" than metal-halide bulbs because the arc is by far the highest intensity of any gas discharge bulb! This is why, despite their lower efficiency, xenon short-arc bulbs are used for searchlights and projectors etc.

For what your doing metal-halide lamps wouldn't be suitable anyway because:
- They take a few minutes to warm up. Not much use if you only have a few minutes of runtime anyway!
- A properly designed ballast is required since they require AC, operate off 100 volts, and the voltage across the arc varies during start-up from around 20v to 100v.

Because xenon short-arc bulbs are DC and start up instantly the voltage across the arc is fairly constant so you might be able to get away with not using a proper ballast and running them straight off batteries. The ignition voltage is also much more than 6kV, probably around 30kV. Anyway you know a lot more about electronics than me so you probably have a much better idea if your plan will work or not!

To find out more about xenon-short arc lamps go to: http://members.misty.com/don/shortarc.html

Re: Building hand-held 3KW HID short-arc spotlight

OK.. changed the title since that totally makes sense.. i've only read about HID including the lamps that output not just insane quantities of light like short-arc but at higher efficiencies as well.. RT3000 will absolutely be 'high intensity'...

Metal halide lamps wouldn't be suitable for me also because i don't have a source of them where somebody will give me one for free :-D

The instant start and DC drive is key to this design.. stupidly simple is the design philosophy... basically once running... the bulb just needs about 24-27V and it'll suck 80-100A based on what voltage is applied in that range... below 80V and it'll blink off... over 100 won't happen.. i'm sure i'll lose a volt from the battery in the circuit losses etc.. I did finally get the batteries today.. and a fully charged battery measured 29.1V (4.15 per cell).. while a mostly depleted battery (showing 25% on the battery gauge).. measured 27.5V (3.92 per cell)... so i think i'm going to be in good luck..

There is a naturally stabilizing function of the internal and circuit resistances to keep a constant current... since... as voltage sags..making current lower at the arc... the lower current will mean less voltage drop on the internal resistances and circuit resistances which will try to keep the voltage at the arc higher and have a stabilizing effect.

We've been solving one problem at at time... first biggie was the battery... next was the 'spark'... then very quickly we realized.. oops.. the battery is going to squelch the spark... so we need a big inductor... one with enough H to keep the spark from affecting the battery but low enough resistance to not loose too much of that precious little overhead i have in Vbat..

With as much load at the batteries have... i would expect them to be just about as stable a voltage source as possible.. just an exponential decay of voltage really.. just hoping i can keep the voltage at the arc above 24 long enough to keep the light lit long enough to be worth the efforts. (although i have very little doubt that'll be a problem... since i can add a 3rd battery if i need to).

I will be doing some load testing soon on the batteries.. maybe tomorrow.. have to find out the resistance of 200ft of 14ga wire :-D I think i figured out i need about 0.6ohm resistance to get the draw i need from the battery and see that the voltage sag will be at 45A.

you are correct about the 6kV... 30 to 50 is probably the range i'm looking for... i was doing my estimate originally not considering the high-pressure noble gas environment inside the bulb but open-air... we did a test earlier with one of our proposed ingniters and w/o the load of the battery and inductor it worked great.. so next test is to test with the inductor.. i might do that test tomorrow also.

-awr