Question re SW0H 350mA Boost MJ Driver

I have this driver in my KeyLux AA. I noticed during a bounce with lightmeter test that the light output drops off very fast with a Lithium and Alkaline battery. I mean really fast, within a minute or so. I found the some info on the 350mA boost MJ driver and it can be used with AA, CR2 and CR123. The efficieny may be better with a 3 volt battery, but is not good with AA's, and not as good as some of the cheaper Finex AA's with two light levels. Now I am not a particular fan of the Fenix, and I own several led Surefire's, two VIP's and two Chameleon's, but the Finex will maintain a flat output on the low setting with one AA, not just a lithium AA. The KeyLux with one NiMh drops off output slower than the Alkalines, and Lithium AA (primary).

I like the KeyLux AA, as it is very well made and reeks quality. Any way to improve the efficiency of my KeyLux AA?

Bill

I'm curious about this as well...

Hi Bill,

Please don't expect too much from my post but I'll give it a stab.

I could be wrong, but I think the NiMh holds voltage better and that probably explains this in the most basic sense.

Do you remember what bin LED is in the can?

Have you ever used your can with 3v or strictly AAs since new?

There are too many variables for me to know for sure and I'm not an expert. I don't think this has much to do with efficiency, just whether the regulation is flat at that input voltage. I think I remember from the past you prefer flat regulation. If I remember correctly I think the term sem-regulated was thrown around for this board? Perhaps it was another.

Anyhow I don't currently have in my possession one of these boards with an H Vf bin LED mounted so I can't try this myself, but I trust your experience. I will get more in a few days or perhaps a week or two and I'll be happy to check this myself to see if it's just your board or whether this is something more universal in terms of performance. I personally don't have much experience with these boards and wanted to do some tests anyhow.

Is there anyone else who can chime in whether this is occuring in their lights?

Chris told me he hasn't noticed this in his light.

Thanks for reply. This is a SWOH binned Lux I. I only have the AA body for my KeyLux AA. I think that it would probably regulate if the vin was closer to vf of led, so a CR123 would work, probably, boosting the voltage to spec. The MJ 350mA boost driver only works in something like direct drive at the low vin available from a single AA. If there was an AA extension available for the KeyLux AA two AA's would probably work well. Of course, this adds length. Most responses to the KeyLux AA are based on subjective observation, and nowhere do you see a runtime plot for the KeyLux AA using the 350mA driver. I used bounce with a lightmeter to determine the runtime characteristic's of the KeyLux with various types of AA's.

Bill

Hi Bill,

I discussed this with Chris and he doesn't experience the same issue with run time or a quick drop off in apparent lumens.

IMO Direct Drive off a AA cell should not be enough to drive an H bin LED. It still requires a boost circuit so I think you are seeing boost, however perhaps it's the combination of your LED and the circuit not putting out what it should? Remember all circuits perform a little different. I cannot answer what the margin would be on these and whether it would be enough to matter.

Is there any chance there is extra resistance in your light with dirty threads or anything that could be an issue such as a canister not fully installed or a tail switch, spring etc. making poor contact or needing cleaning?

Anyhow I will work to decipher this issue if you give me time to do so. I have more SW0H canisters on the way and I will see if I can reproduce your results. I don't have an IS, but I can see a drop off pretty well with a lux meter. If it comes down to it I'll swap canisters with you or whatever makes sense. Ok?

BTW, we are always looking for suitable drivers. I do have a 200mA early Key-LuxAA using MJ's driver if that's really what you want.

Eric, PM sent.

Bill

Sorry I didn't realize this thread earlier...but I just recently(last week) picked up a SW0H and a buncha battery tubes (SF series) I can test that out on AA,CR2,CR123 if you say that the output is dropping really quickly(1st min or 2) then shouldn't be a prob seeing that with my ghetto lightmeter (actually a flashmeter but does lux so heh)

I've only put 1 battery thru it so far...was a sanyo eneloop that I was using with the lantern head...it was still going after 22+hrs... of course the output dropped but...not bad never even got warm but the CR2 that I tried for a few min...got pretty hot after ~5 min
I'll get back to you guys on the output thing tho:thumbsup:

Your best bet is to ask your question here, the original designer MJ may answer your questions.

Hey Bill :wave: I suspect that the step up is too much for a single cell Alkie, or even a Lithium. We're talking at least a 100% step up in voltage to get to the Vf at 350mA even with an H bin. Take into account that the converter efficiency is probably 65-70% (if you're lucky) with this kind of step up and you're probably trying to draw well in excess of an amp from the cell. Lithium will probably be able to provide it for a short burst but not for very long. I don't know how easy it is to rig up a test with a primary CR123 but I bet that the drop off will be much less with a higher input voltage.

Hi Cris, would a converter set up for 200mA's to led work better regulation wise? Have a flatter runtime. I don't expect flat line regulation.

Bill

The lower the current to the LED, the better. Cutting current in half would probably be ideal. I've run a Seoul P4 at 150mA and it still has very decent output. I think that for a single AA, 150mA to 200mA to the LED is a good compromise.