KL1 with 3x123 runtime?

Anyone using a KL1 with three 123's, for example with a UBH? What runtime are you getting? tx.

Edit: DOH! Roy already did a runtime plot. http://ftp2.itexas.net/Rbost/ubhkl19v.jpg Sorry. /ubbthreads/images/graemlins/crazy.gif

Reason for asking: the following looks like a reasonably priced setup for a very long running (8 hours) light:

http://www.tadgear.com/x-treme%20gear/flashlights%20main/vitalgear_fbaa.htm

I'm not using it w/3x123, but IIRC it's supposed to get 7+ hours of regulated runtime.

edit: wonder what happened at the 6 hour mark???

This setup is still one of the best for small light, long runtime, and good brightness. Great camping setup, IMHO. If you run out of 123s, you can stick in two commonly found AAs with a piece of paper (or some leaves?) wrapped around them.

Mark

I've got two extensions on a E1e body, and am running the KL1 on 2AA. For some reason, the fact that it's using AAs, and has the same brightness makes it seem really /ubbthreads/images/graemlins/cool.gif
Guess I'm easily amused...

Does the KL1 work ok once the AA's are down to 2 volts or so?

I don't know. Still on the first pair, and I don't know how to measure them under a load.
Maybe an hour (if that) of runtime, and they're each reading 1.47V right now.

What I'm really wondering is how well the KL1 works with two 1.2 volt AA rechargeables. Anyone tried?

I normally have my KL1 on a UBH-II with 3-123 batteries powering it (still on original set of batteries from earlier this year, great run time), but I just tried a pair of NiMH AA batteries and it works fine with those too. Couldn't tell much difference in light output, but it seems like it is a little brighter with the 3-123 batteries.

-Keith

For rechargeability and guarantee of full brightness, run 3 2/3As. They power the KL1 quite nicely for a good long runtime. They also power the Arc LS well, too...

Mark

That's an interesting idea, feasible but somewhat unattractive if 2xAA works. The best 2/3A NiMH cells at batterystation.com are 1100 mAH, or 3300 mAH for 3 cells, while 2300 mAH AA cells are available for 4600 mAH in 2 cells, more total energy. Somewhat more importantly, AA NiMH chargers including fast chargers are ubuquitous commodity items and most people interested in rechargeables already has a bunch of them. Using 2/3A's would require a special charger, either a slow one (wall wart and limiting resistor) or a fancy one (Maha C777 universal charger or whatever) that's several times as expensive as a comparable AA charger.

So I think I'd rather stay with AA's if they work. If I'm going to use fancy batteries and chargers. I'd probably go for Pila 150S lithium ion cells ($$$$$ though).

I have been running my Arc-LS and SF KL1/E1 off 2x 1/3AA NiCd cells. Don't know what their capacity is, but I get about 1/2hr of brightness before dropping to moon mode. I find that sufficient since I charge them everyday anyway.

PaulR, I think you have some misunderstanding. Since the cells are hooked up in series, the capacity does not increase, only the voltage. Hence with 3 cells of 2/3AA, you will get 3.6V 1100mAh, not 3300mAh. With 2 cells of AA, you will get 2.4V 2300mAh.

If you were looking at incandescents, the starting voltage is very important since it determines how hard the filament would be driven. Hence the 3 cells setup would be more desirable for brightness. It would also be important in unboosted, unregulated LEDs since you need to meet minimum Vf of the LED for a bright light.

It is not so important in a boosted and regulated light, except in determining when the boost circuit cuts out to moon mode. And even then, one must remember that NiCd and NiMH cells discharge with a relatively flat voltage, so the cell would be fairly depleted before its voltage drops far enough to cause the circuit to go out of regulation.

And also with rechargeables, one should not allow them to become severely exhausted as it can cause damage to the internal structure resulting in fewer available cycles. This is a real possibility if we start out with a higher voltage (Vbatt) and allow it to discharge until moon mode kicks in at say Vbatt = 2V. Because at that point, each cell would only be about 0.7V Whereas starting with 2 cells at 2.4V, each cell would display 1V, which is a healthy point to recharge the cells.

In the case of the KL1, I'm not entirely sure at what point the circuit drops out of regulation and moon mode kicks in, but I believe that 2 AA cells would do as well as 3 2/3AA cells in terms of runtime and brightness, but be safer for the cells.

With primary cells, since you can't recharge them, you just want to drain them as far as they will go. So with 3 cells, when you change them, the per-cell voltage would be lower than if you had started with 2 cells.

BTW, if you already have a smart charger, it doesn't matter what size cells you use as it should be able to detect the change in dV as the end of charge cycle approaches. And if you have a dumb charger, well... you could still work out how many hours it would take to charge the cells up. The main thing is building an adaptor to allow the fancy-sized cells to fit into your charger. I've built a couple for my 1/3AA cells from a wooden dowel.

I'm just describing the total energy available, i.e. 2 cells at 2200 mAH is the same total energy as 1 cell at 4400 mAH at the same voltage. It's just easier to compare 2x2400 with 3x1100 than it is to multiply everything out.

The main question here is how low a voltage can the KL1 boost converter work with and still run the LED at full brightness. For the KL4 that cutoff seems to be around 3.3 volts, which is why the 1-cell TW4 isn't as bright as the 2-cell L4. But it sounds like the KL1 does ok at 2.4 volts, which is a good thing, since AA's are the easiest to use.

A typical AA charger simply cannot hold 2/3A cells, since they're too thick to fit in the slots. It might be possible to rig up up some kludge, or use spacers with a C cell charger, but either way is a nuisance. 2/3AA's would fit using some spacers, but their capacity is lower than 2/3A's. (2/3A is not a typo, it's a NiMH cell the exact same size as a 123A, which is 2/3 the length and a little bit thicker than an AA).

Anyway, the Vitalgear setup looks like quite a good deal. Next question is whether the LED's in new KL1's have better color consistency than the early ones did. Everyone was complaining about green or purple beams, poor output, etc. However, Luxeon itself is making much better leds these days, so maybe KL1's have improved. Anyone know?

PaulR: Gotcha. Yeah, 3 cells = more energy. 2/3A is just that little bit thick. I used a dowel that was about C-cell sized. Quick drill with a 15mm dia. wood bit and a 2mm pilot drill. Screw in a pan head self-cutting wood screw. Cut off excess length and shape it a little with a Dremel.

Found out that my charger has 3 different pads so that the larger sized cells can be charged at a slightly quicker rate or something and the adaptor is touching the one for the C cell. Not good since the 1/3AA I have is about 1/10 the capacity of a C. So tack on a longer but AAA cell diameter dowel below with wood glue, cut the screw shorter, solder a wire from the screw to the tip of the smaller dowel, mutter and swear a bit as I get burned, put a blob of solder on the end of the smaller dowel to act as a contact point.

Success. It is now being charged at the rate for the AAA cell, which should be within tolerance.

/ubbthreads/images/graemlins/tongue.gif

Can't say anything about the newer KL1 colour.

Well I'll tell you from personal experience that the 2/3A's work great. I use them in the big Rayovac charger with a couple magnets on each end to take up the slack. Any charger that can handle C or D cells can charge these. Also, I only have 1850mah's to compare with, but this setup has a decent amount more runtime than the 2AAs. 3.6v is almost perfect for a Luxeon and there is almost no converter loss, whereas the 2.4 needs to be stepped up and the KL1 isn't the most efficient around. If anybody wants some to try out, I have a bunch. I have 1100mah nimhs, and 650nicads. The nicads are nice for their super long charge holding and I'd like to try them with a Stinger bulb eventually. One of these days I'll put some up on the trader...

Mark