Questions about modified KL1

I want to buy a modified SFKL1 head with fraen optic and R or S bin driven at 750ma or better.

Basically I want it for throw. The question that I have is how much brighter would this light be compared to the original KL1 and Kl4? have any of you taken comparison photos between the three?

Thanks!

Alex

Hi Al!

How's the airgun biz going?

I got a mod coming from Chop (we had a prior deal where he and I owed each stuff, etc. and we eventually agreed to work it out this way) and you should contact him or CM regarding having one made.

Mine is going to be the mod for the KL4 head, should be killer bright and some decent throw as well, using the KL4's well designed reflector.

Yes, MR Bulk buys mods too!

Oh yeah, and McGizmo makes the McL-4 as well, another great mod!

AlexGT,

Brightness, as a practical matter, is really subjective. The stock KL1 runs at 350mA stock.

Mr. Bulk, chime in if lux readings show otherwise. I don't have a lux meter.

Let's just use a 1W as an example since those are what you mentioned. If you increase the current 100% and go to 700mA, you'll get about 50% more light. It is noticeably brighter and I wouldn't have it any other way. The KL1 will run fine for long periods at 700mA. It can handle this heat.

If you go to one amp, the increase in brightness will be marginal. The reason being the law of diminishing returns, for lack of a better term. As you increase current over 700mA you'll get less of an increase in brightness, but a lot more heat. The batts in a 2X123 configuration will also have a really hard time keeping up with the demand of the circuit and LED at this current. That's why you'll only get around 1 hour of runtime at 1A as opposed to two hours at 700mA.

If you want a good practical light, a KL1 at 700mA driving a nice low Vf high dome with a Fraen LP is the way to go. It's a very cost effective mod and this sucker will THROW. If you're in a situation where the extra light provided by 1A will make a difference, you should have brought a bigger light with you.

As far as going to one amp goes, it is a very bright light, but you really need the right host for it. The KL4 can get by running at 1A because it has more meat by virtue of the mass around the reflector. The KL1 is just a shell. I've sold a few 1A KL1 mods and they are nice. Those that got them like them, but for what they are. INSANE.

If you're interested in something like this, CM does these mods, as do I. PM with questions before you take the plunge. If you like the color of the recent 3W LEDs that have hit the scene, you might want to check those out. I haven't found them to be any brighter, subjectively (Go ahead Charlie, hit me!), but running one of those at 700mA or even 1A would not be overdriving them, but running them to spec.

OK, before I even say anything, Charlie can hit me too. OW!

OK we got that out of the way. I agree with Chop on the 3W Lux. I haven't found them to be any brighter but that's driven at 1A and 700mA. They do seem pretty consistent but so are the Q3J's.

As far as comparing a stock KL1 with a modded KL1, there are significant differences and the big one is beam and color. The stock KL1 has a broad flood beam and is mostly purple at the center with the color fading to white, sometimes yellow and (yuck!) green. They're not dim but they're not very bright either. A KL1 with a high dome will out throw the stock KL1, even without overdrive. Overdrive to double the current will get you about 60% more light which is not significant but it is a discernible difference. Going to 1A will double the light at the expense of a much shorter runtime. 1A will take almost 3x the current and only twice the light. If an hour+ or so of runtime is acceptable, then that's the tradeoff you make. You might be better off with an L4 if you want that much light, or maybe have one of us mod an L4 to a 1W if you want the throw.

CM

Wow! lots of info and I didn't had a chance to read it, lets go step by step.

Hi Mr. Bulk!
The airgun biz is going well, But haven't had time to do much outdoor shooting lately, mostly indoor with an Aeron(sold the Tau)That Mcl-4 is yet another cool light to put on the wishlist.

Hi Chop!
Thanks for the great knowledge you share with me regarding what would be the best mod, I will go for the modded KL1 and have contacted CM regarding this, I just need to make up my mind as to what current would be nice for it, now that I read your post I think I will stay away of the 1 amp. and decide between 700-850 ma range.

Hi CM!
I read your PM and will respond shortly

So guys, What ma.you recommend for a Kl1 that will run from 2 123's 80%+ of the time and rarely on 1 123?

I am thinking something between 750 - 850ma. what do you say?

Thanks and sorry for the delay in my response.

Alex

AlexGT,
Since you're talking about overdriving, I'm gonna guess that you want something brighter than you'd get with the stock bias. If you can live with 2 hours or so of runtime, I'd go with the 600-700mA bias. I say this for a few reasons.

As you approach 1A, you are really starting to tax the batts. At 700mA, you're already looking at only 2 hours of runtime. As you go over 700mA you're really cutting into runtime without getting any meaningful increase in brightness. I mean very little increase in brightness. Remember that going from 700mA to 1A cuts runtime in half.

Another thing is the heat. Of course, as you increase current, you're going to increase heat. I said it before and I'll say it again. I've found 700mA to be the best compromise among runtime, heat, and brightness.

Interestingly, I just built myself an E2e mod. I bored out the bezel and put together on of those ecan/esink setups. I used a Q3J and drove it with a BadBoy500. I was really surprised at how well this compared to a KL4 with Q3J running at 700mA when doing the ceiling bounce test.

Anyway, I'd go with 700mA. It's a good middle of the road mod that will be very useful and won't kill you on battery costs. Going to 750-850mA won't get you anything but less runtime and more heat.

Thanks for the reply Chop!

At 700 ma on 2 123's would the runtime would be @ 2 hours. so I am asumming on the rare ocassion I use 1 123 I would get 45 mins.?

Thanks for all your help. I appreciate it.

Alex

AlexGT,
You'd get something between 30-45 minutes. Remember, going from 2 batts to 1 batt and expecting the same amount of light will put a much bigger strain on the batt. You pay for this in runtime and brightness. I just won't be as bright on 1X123, but still plenty bright.