MR-X with X3T. Hotlips with Magic Resistor TK. #1

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Re: Hotlips w Magic Resistor constant current circ

Chris, I am positively sure about the runtime, I couldn't believe it myself when the DD-LED would'nt turn on for ages /ubbthreads/images/graemlins/grin.gif
Why do you think those batteries have no power? They are rated at 2700mAh which should be considerably more than with your NiMh that should be about 2200mAh top. They have a higher voltage, too, the only thing is that your NiMh's have a ower internal resistance.
Hotbeam said that he tuned my MR-X to 1.52A

Hasn't anybody else tried his MR-X with L91's?

When I should find the time I'll get a current meter ...

bernhard
 
Re: Hotlips w Magic Resistor constant current circ

Burnt, if memory serves, Energizer E2 lithium AA cells are rated 3000mAh, which in theory would drive MR-X for two hours if you could get them to deliver all that energy at constant voltage. Of course you can't, but I could totally be led to believe that Bernhard got 63 minutes and more out of them. Maybe his LED has a slightly lower Vf, too, which would help matters.

As far as the heat, that would be the difference between Vf and the 9V or so that his cells deliver, and if I'm understanding the MR circuit correctly, a lower than average Vf would mean more heat dissipated in the regulator, so this seems totally consistent, too.

Bernhard, hotbeam did some testing with lithium AA's and got disappointing results. I never thought about it before, but maybe the Vf on his emitter is above average and Vf on yours is below average. He probably kept the brightest X3T for himself, right? /ubbthreads/images/graemlins/wink.gif I have a hunch that the brightest X3T might have a higher Vf than the others. More energy... more light!
 
Re: Hotlips w Magic Resistor constant current circ

... meaning I got the crappiest, hm? /ubbthreads/images/graemlins/grin.gif

Well, either way, I like it this way and will continue to use L91s, but I think we simply cannot determine wether this runtime should be normal or not since there have only been three sets ever run through an MR-X, one in hotbeam's and two in mine. Either result doesn't prove anything IMHO.
Did I say I like mine this way?
/ubbthreads/images/graemlins/grin.gif
bernhard
 
Re: Hotlips w Magic Resistor constant current circ

milkey: Perhaps it is a combination of all variables /ubbthreads/images/graemlins/icon3.gif

kiessling: Just as well you like L91s /ubbthreads/images/graemlins/grin.gif
 
Re: Hotlips w Magic Resistor constant current circ

Is the Magic Resistor available for sale on it's own yet?? And if so how much does it cost, i would love to have a couple of these puppies. /ubbthreads/images/graemlins/grin.gif
 
Re: Hotlips w Magic Resistor constant current circ

Meatman... /ubbthreads/images/graemlins/grin.gif There is an old price in the first thread. When run #2 happens, there should be some for sale indiviudually. Remember, the MR is a high power unit and can handle happily up to 3A.
 
Re: Hotlips w Magic Resistor constant current circ

Milky,

That's 63 minutes from batteries that were already flattened to DD LED point the night before. Correct me if I'm wrong Kiessling?

I'm wondering if it has to do with the "?" effect (can't remember the name) - the coating on the plates that after storage needs a small burn-in to remove before full capacity is reached with lithiums. Perhaps this was not able to remove whilst high current was being drawn reducing what the battery could give, yet after a rest the layer was able to remove thereby exposing the full contact area and therefore capacity?

I must try some. As expensive experiment, but worth it for long term storage/infrequent use applications.

Kiessling,

Regardless of each persons personal preferences of battery, if you are happy with the light output and runtime, then I am happy too.

Chris
 
Re: Hotlips w Magic Resistor constant current circ

Burnt, the effect is called "passivation." I'm hardly an expert on the phenomenon, but what you suggest is possible. That dip in Hotbeam's original U5U runtime graph has always been of interest to me, and passivation might explain it.

I also suspect that Vf of the emitter has something to do with things. The lithium AA's should give a flat voltage during discharge, but if that voltage is slightly BELOW the required Vf the DD indicator will be on the entire time. On the other hand, if the voltage is slightly ABOVE required Vf we're in for a long ride in regulation.

Maybe some of each phenomenon. /ubbthreads/images/graemlins/icon3.gif

As an aside, I happen to think lithium AA's aren't as well suited for high current draw as 123's are. I suspect it's the fault of the "AA" architecture, which probably optimizes overall capacity over spewing out all the stored energy at once. Still, a lithium AA will run rings around an alkaline AA. Meanwhile, the lithium AA's don't seem to have the same tendency for spontaneous failure that 123's have. (Ever notice how a 123-based light can work fine one night, then when you turn it on the next night it's dead?)

Given the above, you may be right, lithium AA's might be THE best choice for long term storage with reliability, more so than even 123 cells. In my experience, it seems to be the most stable battery architecture around. Bernhard's onto something! /ubbthreads/images/graemlins/smile.gif

Now a question for you, Burnt: if MR-X doesn't get hot when running in regulation with NiMH but does get hot when using something else, like Li-ion or 123 cells, does that suggest the heat's NOT coming from the emitter, but from the regulator itself? That's what the evidence seems to say to me, the rationale being that under regulation the emitter's got to be getting the same power (wattage), and hence generating the same amount of heat, in all cases. If so, that would be good news, as it means those "hot" batteries aren't cooking my precious X3T emitter!
 
Re: Hotlips w Magic Resistor constant current circ

Burnt, you're wrong here, sorry for being unclear!
I used the light for 17 minutes in the first night without the DD-LED coming on, I had to stop the test because I had to go to bed /ubbthreads/images/graemlins/grin.gif
the second night I continued with the same batteries that had never reached DD and got another 63 minutes in regulation before the DD-LED finally came on. By that time I was barely able to touch the bezel for a few seconds.

WIll do an alkaline test ... /ubbthreads/images/graemlins/grin.gif

bernhard
 
Re: Hotlips w Magic Resistor constant current circ

[ QUOTE ]
Kiessling said:
... By that time I was barely able to touch the bezel for a few seconds....


[/ QUOTE ]

Bernie, THAT'S one way to kill your Luxies /ubbthreads/images/graemlins/grin.gif
 
Re: Hotlips w Magic Resistor constant current circ

tried it with Duracell ProCell Alkalines and got 6min continous burn untill the DD LED came on. Same results as before the fix. Alkies are obviously not the way to go. Just in case you didn't already know. /ubbthreads/images/graemlins/grin.gif

Howard, is this too much for the poor thing? The L4 gets that hot, too. Should I stop doing that?

bernhard
 
Re: Hotlips w Magic Resistor constant current circ

6 mins with the ALKS. Even that is amazing. Must be something they put in batteries that go to the 'Old World' /ubbthreads/images/graemlins/grin.gif. Now, try some Old World 2000+mAh NiMh. Maybe you'll get 2 hours from one set /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Too much? Well, you are putting ~10w of power to the LED for 1 hour and without ventilation (I presume it is just sitting there on your table or something)... How would you feel? /ubbthreads/images/graemlins/grin.gif If there was any light you want to do this test to, a Hotlipped light would be it. That you can rest assure about. /ubbthreads/images/graemlins/smile.gif That L4 you tested... once or twice would be ok but continued tests like that surely does the light no good.

When you use it in real life, your hand takes a good lot of heat away. Also the air convection due to movement also reduce heat. Sitting there stationery... well... now that you have done it, there is probably no need to do it again /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

But then.... IT'S YOUR LIGHT /ubbthreads/images/graemlins/wink2.gif
 
Re: Hotlips w Magic Resistor constant current circ

ok, got the hint /ubbthreads/images/graemlins/tongue.gif
no free new X3T emitter should I smoke this one ...

seriously now ... what runtimes do YOU get with L91s and Alks?
maybe I am just mad or stupid or both?

bernhard
 
Re: Hotlips w Magic Resistor constant current circ

milkey:

[ QUOTE ]
Now a question for you, Burnt: if MR-X doesn't get hot when running in regulation with NiMH but does get hot when using something else, like Li-ion or 123 cells, does that suggest the heat's NOT coming from the emitter, but from the regulator itself? That's what the evidence seems to say to me, the rationale being that under regulation the emitter's got to be getting the same power (wattage), and hence generating the same amount of heat, in all cases. If so, that would be good news, as it means those "hot" batteries aren't cooking my precious X3T emitter!


[/ QUOTE ]

I'll let Burnt answer this one in full Milkey /ubbthreads/images/graemlins/smile.gif but there are really 2 issues here...
1. Heat from excess/wasted voltage (L91s) ---> heat here comes from the FET + emitter
2. Heat from runtime build-up (NiMh, Li-ions) ---> heat here is predominantly from emitter.


kiessling:

Silly? No one is silly here. /ubbthreads/images/graemlins/smile.gif Runtime, cant remember now but NO WHERE near as long as what you are getting.
 
Re: Hotlips w Magic Resistor constant current circ

Kiessling,

I stand corrected on using flattened L91's. Now I really must try some.

Milky,

Hotbeam pretty much summed it up, but for the record:

The MR is specifically designed with batteries with low voltage overhead where a switching circuit just can't keep up for efficiency eg NiMH's especially, or 2 X Li-Ions (7.2V or less under load of 1.5A).

It is a linear circuit.

Using either NiMH's, Li-Ions, alkalines, and zinc carbon the heat is pretty much all from the LED ie 10W 10W with DD LED NOT on, less with it on.

Using 6 X L91 lithiums in series the voltage overhead is greater, perhaps a couple of volts under a load of 1.5A. This results in a larger voltage drop across the MR and therefore more heat from the MR. I have not tried L91's, but suspect a couple of watts is 'lost' - being dropped across the MR. A couple of watts sounds bad, but that adds up to 83% efficient. It's not too bad, but hitting the point a switching buck converter may be better, if only one were available for this current. Of course a buck wouldn't cut it with NiMH's or perhaps even Li-Ions for the efficiency of MR. In either case, all heat you feel is from LED and/or LED + MR (lithiums).

That being said, 123's may fair better as they seem to have a tendency to limit the maximum current they can supply to around the 1.5A mark on average. They seem, at high currents at least, to give the characteristics of having high internal impedance so 3 X 123's may not get as hot as 6 X L91's? I haven't tried either so I'm going on what I've read.

In short, re "if MR-X doesn't get hot when running in regulation with NiMH but does get hot when using something else, like Li-ion or 123 cells, does that suggest the heat's NOT coming from the emitter, but from the regulator itself?" .....correct, but 10 W is comming from the emitter regardless of batteries but only when the the DD LED is NOT on. If the DD LED is on then as close to 100% as you'll get is coming from the LED (<10W). Under ANY condition, no more than 10W will be dissipated by the LED, give or take a tad for variation in Vf's (MR regulates current).

Hope I didn't prattle on too much.

Chris
 
Re: Hotlips w Magic Resistor constant current circ

Hey, I'm not on the map!!! /ubbthreads/images/graemlins/mecry.gif

Of course, mine is not a TK unit, and I am using a 3 cell OAD body running 12 Kirkland Signature alkaline AA's serial/parallel for two 9v banks.

BTW, the two banks of 6 AA's seem to work pretty dang well. I got around two hours + regulated before the DD LED came on. Mind you that this was not constant on, but a bit of use every night for about a week. I still haven't changed the batteries, as the light still seems to be nearly as bright as when in regulation. It has easily seen five hours of use by now, probably more. However, it still seems pretty dang bright. /ubbthreads/images/graemlins/thinking.gif

My theory on this is that the light should remain in regulation until the batteries reach approximately 1.1 volts each (my X3T's Vf is 6.7v and the batts. measured just under 1.1v each when the DD LED came on). Energizer states that AA's can provide 1A for for one hour, and at the end of that time, the batteries will be at 0.8v. Along those same lines, they can provide about 800mA for about an hour and end at 1.0v. I think what I'm trying to say is that one bank of alkaline AA's just can't cut it, but when you have two bank's in parallel to share the load, they hold up MUCH better!

Based on these specs, and the 5.7Ah capacity of the 12 AA's (2850mAh for each bank) my batteries must be on their last leg. I'll have to take them out and measure them now, but they still seem to be working OK...

Maybe it's because even if they can only put out 350mA per bank, that's still 700mA to the X3T which is stiil running at spec. /ubbthreads/images/graemlins/icon3.gif

All I can say is that I am a happy camper... /ubbthreads/images/graemlins/thumbsup.gif

MR-X rules!!! /ubbthreads/images/graemlins/buttrock.gif
 
Re: Hotlips w Magic Resistor constant current circ

LEDmodMan,

Five hours is a long time /ubbthreads/images/graemlins/grin.gif.

If you can handle the charging of NiMH's though I'd still recommend those from a cost perspective as you enter the short day's of winter. You seem to like using the MR-X, and why not - it's intended to be used frequently. With your usage NiMH's would pay for themselves over the coming winter easily. Stick to 6 X NiMH's - it's all that is required.

The alkalines do indeed drag on for a looooong time. Your thoughts re current capability for 2 banks vs 1 and current vs brightness is correct. You'll find good usable light right down to about 100 - 200mA drive so you have a way to go yet before changing them. Fortunately the MR will be about 99.5% efficient once the DD LED comes on so happily drain those alkalines right down to the last drop knowing it's all LS light you're getting for the power being drained with no waste /ubbthreads/images/graemlins/smile.gif

Chris
 
Re: Hotlips w Magic Resistor constant current circ

Wylie, see the graph on the first page.
 
Re: Hotlips w Magic Resistor constant current circ

[ QUOTE ]
hotbeam said:
A few of you have asked for instructions on how to reduce the current the MR-X feeds to the X3T. I'll bet it has something to do with Homebrew's post. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif Well... here they are:

Removing MR Hotlips from the OA2D
<ul type="square">[*]Use a thin but strong blade to separate the lips on the Hotlips from the rim of the OA2D.
[*]Once you have a ~1mm gap, insert a flat head screwdriver or similar in between and twist SLOWLY until the gap widens to ~5mm. Try not to damage the lips on the MR Hotlips.
[*]Grip the Hotlips with a rubber glove or equivalent and SLOW wiggle it away from the OA2D rim until it dislodges. You will see 4 wires: blue, white, red and black
[*]CAREFULLY lay the MR Hotlips with the circuit showing on a soft, padded surface. Remember the X3T is on the other side!!!
[*]You will also see the brownish thermal conducting material around the rim of the Hotlips. Put this away for the moment. You will need it again when you put the MR Hotlips back
[/list]

Changing the drive current
<ul type="square">[*]Measure the voltage between the switch negative and the FET source with a DMM. You will get 225mV. See diagram for component location.
[*]Use a 2mm jewel screwdriver to DECREASE the current drive on the MR-X by turning the potentiometer ANTI-CLOCKWISE.
[*]To set the current exactly, you need 3 hands /ubbthreads/images/graemlins/grin.gif. With the DMM in place and its readout visible, turn the pot ANTI-CLOCKWISE until the voltage reading matches those below. Do this reasonably QUICKLY as you will feel the Hotlips start to get warm after ~30-60secs.
[*]1.5A, 22.5mV
1.25A, 18.75mV
1A,15mV
750mA, 11.25mV
[/list]
MRcircuit.jpg



Reinstalling the MR Hotlips
<ul type="square">[*]CAREFULLY place the MR Hotlips back into the OA2D to ensure the wires fit nicely
[*]Remove the MR Hotlips again and now wrap the thermally conductive strip around the side of the Hotlips, giving it enough tension so that it will fit back into the OA2D.
[*]That's it!
[/list]


PS. You should be relatively savvy with using simple tools, have a steady hand and know how to use the DMM. Please be careful. You are modifying this at your own risk. Send it to me or a competent fellow MR-Xer if you want a hand.





[/ QUOTE ]


Here you go DZ. Getting the photo for you. Somehow, it has expired /ubbthreads/images/graemlins/icon3.gif
 
Re: Hotlips w Magic Resistor constant current circ

Appreciate it HT, I was starting to go through this thread again & took a break. It's very time consuming although I did learn alot more great things about the MR-X.

Whew, you saved the day!

Many thanks! /ubbthreads/images/graemlins/thumbsup.gif
 
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