Lunarmodule
Enlightened
Eh, howzit! Shoots! Minors, braddah! Get um one da kine Fivemega adapter, garans it work allright lidat, not junks. [end pidgin] :laughing:
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SF/M6
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Eh, howzit! Shoots! Minors, braddah! Get um one da kine Fivemega adapter, garans it work allright lidat, not junks. [end pidgin] :laughing:
js
Flashlight Enthusiast
Lunarmodule said:Will, I think Luna's correct and it adheres nicely to the KISS principle for running the LOLA. The MN20 (LOLA) is actually a 7.2V lamp that draws 2.45 amps for approximately 17 Watts of output. The MN21 (HOLA) spec is 6.1V with 4.9 amps for about 30W. The common denominator between these two different loads is the right amount of sag with the MB20 holder. I suspect a potential for instaflash with the LOLA with the triple parallel.
Actually, I've been having so much fun with the rechargeable HOLA I havent yet focused on the LOLA application in great detail. Thats a logical next step, go for increased LOLA runtime. I'm receiving some help in regards to a circuit for the pack that limits excessive voltage to guard against instaflash and compatibility with the LOLA. I did instaflash a MN21 when I replaced partially discharged (3.8V) R123s in the MB20 stock holder and THAT was a painful $30 per second mistake so I am a tad leery of killing a LOLA. The LOLA is scarce as all get out until production resumes in Feb/Mar and I gave mine to a friend with another M6 so that solution may have to wait. All dealers I've contacted are out of LOLA stock
TBC
The MN21 is a 6.8 volt lamp on fresh 123's, and the MN20, is, about a 7.6 volt lamp, on fresh 123's, although I haven't actually done a direct measurement of this myself yet. Now, mid-point-voltage is probably just as brock specifies on his webpage. But fresh, start of run voltage, is more important information to have when you are trying to match lamps and batteries.
The nice thing about direct-drive with Li-ion cells, is that they will likely rise up in voltage under load (just as CR123's do) so that you can power either the MN21 or the MN20 to the right level.
Pretty much, I would say the following: if your setup nicely direct-drives the MN21, then it will nicely direct-drive the MN20, although if you are OVER driving the MN21 too much, it will possibly flash the MN20, as it is more over-driven in stock configuration than the MN21.
For the M6-R, which is not direct-drive, but rather fully regulated, you have to use the MN16 as the LOLA instead of the MN20, but this is only because it maintains a constant 6.8 volts DC-equivalent at the lamp no matter what the current draw (within reason). So since I set it up to drive the MN21 perfectly, it under-drives the MN20. But since the MN16 is also perfectly driven at 6.8 VDC, it's no big deal.
However, as I said, going with direct drive, the MN20 will probably be fine if the MN21 is fine.
Good luck, and some nice stuff here! Good ideas!
js
Flashlight Enthusiast
4.9 to 5.0 amps times 6.8 volts equals 33.3 to 34 watts.
CLHC
Flashaholic
Lunarmodule said:
It's been a while since I've spoken and heard that kind of talk. He he he. . .I'm already "haolefied"(sp?) here.
Anyways, thanks for the recommendation I'm going to do that.
js
Flashlight Enthusiast
Luna said:
Correct. Brock's measurements are off. At least I think they are.
Getting a correct current measurement is ALWAYS rather tricky, especially with low voltages and high draws. I know for a certainty that the starting voltage is 6.8 volts for three reasons:
1. I measured it directly (and it wasn't fun to set up).
2. Willie Hunt told me that starting with fresh 123's at room temp it was 6.8 VDC (and I suppose he should know)
and
3. My M6-R packs are set to precisely 6.8 volts DC equivalent, and I can not tell the difference between a fresh MB20 and an M6-R pack. For whatever that's worth.
As for the current draw, let's run some numbers. Let's assume that the GP 1100's deliver right around 1050 mAh even at 3C draws, and that their mid-point or average voltage is 1.2 volts/cell. (Both of these assumptions are generous, and thus we will probably OVER estimate the current draw). So, the average ratio of the voltages is thus 10.8 / 6.8 = 1.588 advantage. And again, this is being generous due to the high instantaneous current draws on the battery pack. So this means an apparrent capacity of 1.6674 AH due to the voltage advantage.
OK. Now, we know that the M6-R will run for just about 19.5 minutes. This is a 3.077 C rate. Multiply by the apparent or equivalent capacity and you get 5.1 amps draw rate. However, deduct for the less than 100 percent efficiency of the regulator, and you get 5.02 amps. So call it an even 5.0. Then if you start trying to be a touch more realistic about the real WH delivered by the pack, you might call it 4.9 amps.
So that's why I put 4.9 to 5.0 amps above.
Plus, really, if you think about it, the 1185 on 9 good NiMH cells is definitely brighter than the M6 HOLA. It in no sense blows it away. But it does "win". It is a, what?, 35 watt lamp at that voltage? And I know for a fact that SF doesn't use lamps that are inefficient. Some are more efficient than others, but all of them are high pressure xenon lamps. So if you are doing the math, and the M6 HOLA is a 5.5 amp, 6.8 volt, 37 watt lamp outputting 630 torch lumens (my estimate) that means an efficiency of 26 lumens/watt, which means a CCT of 3200 K, which is low, I think. The MN21 at 6.8 volts is pretty white.
Plus, Willie told me that driving the MN21 at 7.0 volts was right near the melting point of the filament, so 6.8 volts has to be at a higher drive level than 3200 K.
But, if you assume a 33 watt lamp outputing 630 torch lumens (which is only 65 percent of bulb lumens), you get 29 lumens/watt, which would be very close to 3300 K, which is about what my eye sees.
Eh. I don't know. The above bit was all just hand waving, back of the envelope calculation, and relies on all of my assumptions. So take it or leave it.
But the battery pack WH calculation is pretty hard and fast. If the MN21 were really drawing more than 5 amps, I just don't think I could get the M6-R to run for 19.5 minutes.
Of course, I could have made a mistake somewhere along the line. But until someone shows it to me and backs up the correction, I think I will stick to my MN21 figures: 4.9 amps 6.8 volts.
You are free to take them or leave them.
Oh, actually, I just thought of one more piece of evidence:
This is tweek's graph on the LG chem 2400 mAh 18650. If you look at the 4.8 amp discharge curve, you will see that these cells deliver just about 1.65 AH at this draw rate. And we know that two of these will drive the MN21 for 20 minutes, which is 3C, which means 4.95 amps, although this would be at 6.6 volts, which is the mid-point-voltage. So that would mean, 5.03 amps at 6.8 volts.
OK. Well, I'm starting to lose interest. Maybe I need more coffee.
But whatever. I think that it is very safe to say that there is no way the MN21 is a 5.5 amp lamp. 4.9 to 5.1 or even 5.2 if you MUST, but no way it is 5.5.
At some point I will get setup to do a really accurate current measurement. I have the equipment to do it, I'm just friggin' swamped with modding work right now and can't justify it.
Hope that was helpful and not inflamatory. I really don't care to argue about it today.
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js
Flashlight Enthusiast
*EDIT* YES THIS IS A DOULBE POST, BUT THIS (insert many swear words yelled in a very annoted tone of voice here) WINDOWS MACHINE SIMPLY WON'T ALLOW ME TO EDIT IT. EVERYTIME I DO IT LOCKS UP. So admins feel free to delete the first post. thanks
Correct. Brock's measurements are off. At least I think they are.
Getting a correct current measurement is ALWAYS rather tricky, especially with low voltages and high draws. I know for a certainty that the starting voltage is 6.8 volts for three reasons:
1. I measured it directly (and it wasn't fun to set up).
2. Willie Hunt told me that starting with fresh 123's at room temp it was 6.8 VDC (and I suppose he should know)
and
3. My M6-R packs are set to precisely 6.8 volts DC equivalent, and I can not tell the difference between a fresh MB20 and an M6-R pack. For whatever that's worth.
As for the current draw, let's run some numbers. Let's assume that the GP 1100's deliver right around 1050 mAh even at 3C draws, and that their mid-point or average voltage is 1.2 volts/cell. (Both of these assumptions are generous, and thus we will probably OVER estimate the current draw). So, the average ratio of the voltages is thus 10.8 / 6.8 = 1.588 advantage. And again, this is being generous due to the high instantaneous current draws on the battery pack. So this means an apparrent capacity of 1.6674 AH due to the voltage advantage.
OK. Now, we know that the M6-R will run for just about 19.5 minutes. This is a 3.077 C rate. Multiply by the apparent or equivalent capacity and you get 5.1 amps draw rate. However, deduct for the less than 100 percent efficiency of the regulator, and you get 5.02 amps. So call it an even 5.0. Then if you start trying to be a touch more realistic about the real WH delivered by the pack, you might call it 4.9 amps.
So that's why I put 4.9 to 5.0 amps above.
Plus, really, if you think about it, the 1185 on 9 good NiMH cells is definitely brighter than the M6 HOLA. It in no sense blows it away. But it does "win". It is a, what?, 35 watt lamp at that voltage? And I know for a fact that SF doesn't use lamps that are inefficient. Some are more efficient than others, but all of them are high pressure xenon lamps. So if you are doing the math, and the M6 HOLA is a 5.5 amp, 6.8 volt, 37 watt lamp outputting 630 torch lumens (my estimate) that means an efficiency of 26 lumens/watt, which means a CCT of 3200 K, which is low, I think. The MN21 at 6.8 volts is pretty white.
Plus, Willie told me that driving the MN21 at 7.0 volts was right near the melting point of the filament, so 6.8 volts has to be at a higher drive level than 3200 K.
But, if you assume a 33 watt lamp outputing 630 torch lumens (which is only 65 percent of bulb lumens), you get 29 lumens/watt, which would be very close to 3300 K, which is about what my eye sees.
Eh. I don't know. The above bit was all just hand waving, back of the envelope calculation, and relies on all of my assumptions. So take it or leave it.
But the battery pack WH calculation is pretty hard and fast. If the MN21 were really drawing more than 5 amps, I just don't think I could get the M6-R to run for 19.5 minutes.
Of course, I could have made a mistake somewhere along the line. But until someone shows it to me and backs up the correction, I think I will stick to my MN21 figures: 4.9 amps 6.8 volts.
You are free to take them or leave them.
Oh, actually, I just thought of one more piece of evidence:
This is tweek's graph on the LG chem 2400 mAh 18650. If you look at the 4.8 amp discharge curve, you will see that these cells deliver just about 1.65 AH at this draw rate. And we know that two of these will drive the MN21 for 20 minutes, which is 3C, which means 4.95 amps, although this would be at 6.6 volts, which is the mid-point-voltage. So that would mean, 5.03 amps at 6.8 volts.
OK. Well, I'm starting to lose interest. Maybe I need more coffee.
But whatever. I think that it is very safe to say that there is no way the MN21 is a 5.5 amp lamp. 4.9 to 5.1 or even 5.2 if you MUST, but no way it is 5.5.
At some point I will get setup to do a really accurate current measurement. I have the equipment to do it, I'm just friggin' swamped with modding work right now and can't justify it.
Hope that was helpful and not inflamatory. I really don't care to argue about it today.
Luna said:
Correct. Brock's measurements are off. At least I think they are.
Getting a correct current measurement is ALWAYS rather tricky, especially with low voltages and high draws. I know for a certainty that the starting voltage is 6.8 volts for three reasons:
1. I measured it directly (and it wasn't fun to set up).
2. Willie Hunt told me that starting with fresh 123's at room temp it was 6.8 VDC (and I suppose he should know)
and
3. My M6-R packs are set to precisely 6.8 volts DC equivalent, and I can not tell the difference between a fresh MB20 and an M6-R pack. For whatever that's worth.
As for the current draw, let's run some numbers. Let's assume that the GP 1100's deliver right around 1050 mAh even at 3C draws, and that their mid-point or average voltage is 1.2 volts/cell. (Both of these assumptions are generous, and thus we will probably OVER estimate the current draw). So, the average ratio of the voltages is thus 10.8 / 6.8 = 1.588 advantage. And again, this is being generous due to the high instantaneous current draws on the battery pack. So this means an apparrent capacity of 1.6674 AH due to the voltage advantage.
OK. Now, we know that the M6-R will run for just about 19.5 minutes. This is a 3.077 C rate. Multiply by the apparent or equivalent capacity and you get 5.1 amps draw rate. However, deduct for the less than 100 percent efficiency of the regulator, and you get 5.02 amps. So call it an even 5.0. Then if you start trying to be a touch more realistic about the real WH delivered by the pack, you might call it 4.9 amps.
So that's why I put 4.9 to 5.0 amps above.
Plus, really, if you think about it, the 1185 on 9 good NiMH cells is definitely brighter than the M6 HOLA. It in no sense blows it away. But it does "win". It is a, what?, 35 watt lamp at that voltage? And I know for a fact that SF doesn't use lamps that are inefficient. Some are more efficient than others, but all of them are high pressure xenon lamps. So if you are doing the math, and the M6 HOLA is a 5.5 amp, 6.8 volt, 37 watt lamp outputting 630 torch lumens (my estimate) that means an efficiency of 26 lumens/watt, which means a CCT of 3200 K, which is low, I think. The MN21 at 6.8 volts is pretty white.
Plus, Willie told me that driving the MN21 at 7.0 volts was right near the melting point of the filament, so 6.8 volts has to be at a higher drive level than 3200 K.
But, if you assume a 33 watt lamp outputing 630 torch lumens (which is only 65 percent of bulb lumens), you get 29 lumens/watt, which would be very close to 3300 K, which is about what my eye sees.
Eh. I don't know. The above bit was all just hand waving, back of the envelope calculation, and relies on all of my assumptions. So take it or leave it.
But the battery pack WH calculation is pretty hard and fast. If the MN21 were really drawing more than 5 amps, I just don't think I could get the M6-R to run for 19.5 minutes.
Of course, I could have made a mistake somewhere along the line. But until someone shows it to me and backs up the correction, I think I will stick to my MN21 figures: 4.9 amps 6.8 volts.
You are free to take them or leave them.
Oh, actually, I just thought of one more piece of evidence:
This is tweek's graph on the LG chem 2400 mAh 18650. If you look at the 4.8 amp discharge curve, you will see that these cells deliver just about 1.65 AH at this draw rate. And we know that two of these will drive the MN21 for 20 minutes, which is 3C, which means 4.95 amps, although this would be at 6.6 volts, which is the mid-point-voltage. So that would mean, 5.03 amps at 6.8 volts.
OK. Well, I'm starting to lose interest. Maybe I need more coffee.
But whatever. I think that it is very safe to say that there is no way the MN21 is a 5.5 amp lamp. 4.9 to 5.1 or even 5.2 if you MUST, but no way it is 5.5.
At some point I will get setup to do a really accurate current measurement. I have the equipment to do it, I'm just friggin' swamped with modding work right now and can't justify it.
Hope that was helpful and not inflamatory. I really don't care to argue about it today.
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js
Flashlight Enthusiast
Oh, and Luna, you should be using the re-rating formulas for determining what the currents and lumens output and lifespan of over or under driven lamps are:
Ir = (Va/Vd)^0.55 * Id
Cr = (Va/Vd)^3.5 * Cd
Lr = (Vd/Va)^12 * Ld
The sub "r" = re-rated, and the sub "d" = design. "L" is life. "C" is mean spherical candlepower, or bulb lumens, and, "I" = current.
Ir = (Va/Vd)^0.55 * Id
Cr = (Va/Vd)^3.5 * Cd
Lr = (Vd/Va)^12 * Ld
The sub "r" = re-rated, and the sub "d" = design. "L" is life. "C" is mean spherical candlepower, or bulb lumens, and, "I" = current.
wquiles
Flashaholic
js said:
Yes, it was helpful. To me at least it was very educational and I learned lots from it :bow:
Will
No arguments here as I was hoping you had measured it,
I've been to lazy/busy to rigg-up the I/E test myself though I do get a stabilized I of 4.86A when leftover capacity is around 2100mah (I retested last night, 5.1-5.2a full charge but I haven't measure the voltage yet).
I've been to lazy/busy to rigg-up the I/E test myself though I do get a stabilized I of 4.86A when leftover capacity is around 2100mah (I retested last night, 5.1-5.2a full charge but I haven't measure the voltage yet).
js said:
Ok this one I will argue
What is wrong with the ohmic approximation of a filament?
Even though the resistance of the tungsten filament increases over 15 times as it is heated from roomtemperature to 3000K, once at this high temp ,you will have very little change in resistance. Simply stated, i=er would work well in this situation just as it was taught to us in Circuits1 EE course
As for approximating color temp try this:
T = -1.86(R/R0)^2 + 206.6(R/R0) +118
R= resistance of filament at temp
R0=roomtemp(0 really but no need to freeze it)
SilverFox
Flashaholic
Hello Lunarmodule,
Regarding the safety of running a series parallel battery pack...
I have no problem running the light this way. The concern comes when you go to recharge your cells. If you plan to do each cell individually, there is no problem. If you plan to charge your cells in the battery holder, then you need to be diligent of each cells voltage and make sure they are balanced with each other.
Driving the cells hard tends to multiply any differences in capacity and the cells tend to go out of balance faster. If you keep track of things, you may only need to re-balance things every so often. If you don't keep track of the balance of your cells, you could end up with "rapid disassembly accompanied by flame..."
If you use protected cells and run the battery pack down to where the protection circuit kicks in, you may have problems getting your charger to register the right number of cells, and may also have problems with a low voltage alarm.
Once again, if you pull the cells and charge them individually, there should be no problems.
Tom
Regarding the safety of running a series parallel battery pack...
Lunarmodule said:
I have no problem running the light this way. The concern comes when you go to recharge your cells. If you plan to do each cell individually, there is no problem. If you plan to charge your cells in the battery holder, then you need to be diligent of each cells voltage and make sure they are balanced with each other.
Driving the cells hard tends to multiply any differences in capacity and the cells tend to go out of balance faster. If you keep track of things, you may only need to re-balance things every so often. If you don't keep track of the balance of your cells, you could end up with "rapid disassembly accompanied by flame..."
If you use protected cells and run the battery pack down to where the protection circuit kicks in, you may have problems getting your charger to register the right number of cells, and may also have problems with a low voltage alarm.
Once again, if you pull the cells and charge them individually, there should be no problems.
Tom
Lunarmodule
Enlightened
:wow::thanks: JS, SilverFox, and Luna:
Sincerest gratitude for your contributions. The information and comments you provided are both very helpful and educational for me. I am honored to have you take notice of these happenings and post about them. I just passed the 25th cycling of the R123 six pack and still cannot believe how beautiful the beam is. I have not measured Vbulb directly during use as it is too much of a PITA to set up but current averages 4.9A. I believe I'm very close to the 7.0V point under load, likely just below it. I have a Fivemega 3" head / 6AA big body light I use to run the 1185 with 3 LG 2400mah 18650s in series. It produces an incredible beam, but qualitatively I have to say the M6 with MN21 in overdrive is visually much more stunning and practical for near field and midrange use. The M6 with MN21 continues to impress me, whereas I've gotten acclimated to the likes of a well driven 1185. The almost absurdly large WHITE mass of light produced by the overdriven MN21 just drops my jaw. I have maybe 8-9 hours on the same bulb driven this way so far, maybe I'm just really lucky with the bulb life.
Funny mentioning the 1185. I have set wheels in motion to fabricate a machined pedestal bipin socket for the M6 head. This may blow the minds of purists, but curiosity and fun dictate the exploration of a hybridization like this. My ARCmania Lux V tower module performs brilliantly in the M6 head, and the likes of a WA 1331 or 1185 might be interesting with careful alignment of the lamp and a different power pack arrangement. A soft start gizmo is also forthcoming. Of course for now my reference standard for subjective excellence remains the MN21 in the M6 with LiIon power.
SilverFox, many thanks for putting that concern in my mind finally at ease. Excellent advice and recommndations. Regarding battery charging, I have done both methods, usually pack charging at 300mA @ 8.4V but occasionally disassembling the pack to check individual cell voltages. I started with brand new cells and have never split up the pack in any way. Individual cell charging was done in th beginning but have had good results with my LiIon pack charger. Cell voltages vary no more than +-0.005V from each other. No apparent change (reduction) in capacity. I figure I'd recharge the pack gently to make up for its 2C discharge, and 300mA seems gentle. I've ordered some 750mA protected cells to try in the setup which would make for more worry free operation with a low voltage cutoff, although I am very attuned to any change in brightness and always shut the light down before the pack reaches 3.5V/cell (open circuit V). Future plans are to incorporate a six pack of 17500 cells.
I may be repetitive but again extend my thanks to those who contribute material here. I enjoy the dialog a great deal and it especially benefits me (and I hope many others) educationally. I find the sense of helpful samaritanism thats commonplace here on CPF to be a shining model that I wish was more prevalent in everyday society. Some exceptional personalities gathered here in this virtual commonwealth and their interaction reveals so much of what is good in human nature and very little of what isnt. Had to throw that little editorial in at the end here, I'm just warm and fuzzy with the spirit of the community here.
Sincerest gratitude for your contributions. The information and comments you provided are both very helpful and educational for me. I am honored to have you take notice of these happenings and post about them. I just passed the 25th cycling of the R123 six pack and still cannot believe how beautiful the beam is. I have not measured Vbulb directly during use as it is too much of a PITA to set up but current averages 4.9A. I believe I'm very close to the 7.0V point under load, likely just below it. I have a Fivemega 3" head / 6AA big body light I use to run the 1185 with 3 LG 2400mah 18650s in series. It produces an incredible beam, but qualitatively I have to say the M6 with MN21 in overdrive is visually much more stunning and practical for near field and midrange use. The M6 with MN21 continues to impress me, whereas I've gotten acclimated to the likes of a well driven 1185. The almost absurdly large WHITE mass of light produced by the overdriven MN21 just drops my jaw. I have maybe 8-9 hours on the same bulb driven this way so far, maybe I'm just really lucky with the bulb life.
Funny mentioning the 1185. I have set wheels in motion to fabricate a machined pedestal bipin socket for the M6 head. This may blow the minds of purists, but curiosity and fun dictate the exploration of a hybridization like this. My ARCmania Lux V tower module performs brilliantly in the M6 head, and the likes of a WA 1331 or 1185 might be interesting with careful alignment of the lamp and a different power pack arrangement. A soft start gizmo is also forthcoming. Of course for now my reference standard for subjective excellence remains the MN21 in the M6 with LiIon power.
SilverFox, many thanks for putting that concern in my mind finally at ease. Excellent advice and recommndations. Regarding battery charging, I have done both methods, usually pack charging at 300mA @ 8.4V but occasionally disassembling the pack to check individual cell voltages. I started with brand new cells and have never split up the pack in any way. Individual cell charging was done in th beginning but have had good results with my LiIon pack charger. Cell voltages vary no more than +-0.005V from each other. No apparent change (reduction) in capacity. I figure I'd recharge the pack gently to make up for its 2C discharge, and 300mA seems gentle. I've ordered some 750mA protected cells to try in the setup which would make for more worry free operation with a low voltage cutoff, although I am very attuned to any change in brightness and always shut the light down before the pack reaches 3.5V/cell (open circuit V). Future plans are to incorporate a six pack of 17500 cells.
I may be repetitive but again extend my thanks to those who contribute material here. I enjoy the dialog a great deal and it especially benefits me (and I hope many others) educationally. I find the sense of helpful samaritanism thats commonplace here on CPF to be a shining model that I wish was more prevalent in everyday society. Some exceptional personalities gathered here in this virtual commonwealth and their interaction reveals so much of what is good in human nature and very little of what isnt. Had to throw that little editorial in at the end here, I'm just warm and fuzzy with the spirit of the community here.
js
Flashlight Enthusiast
Luna said:Ok this one I will argue
What is wrong with the ohmic approximation of a filament?
Even though the resistance of the tungsten filament increases over 15 times as it is heated from roomtemperature to 3000K, once at this high temp ,you will have very little change in resistance. Simply stated, i=er would work well in this situation just as it was taught to us in Circuits1 EE course
As for approximating color temp try this:
T = -1.86(R/R0)^2 + 206.6(R/R0) +118
R= resistance of filament at temp
R0=roomtemp(0 really but no need to freeze it)
The problem with an ohmic approximation is that it is wrong.
Period.
You need to use the re-rating formulas. But I disdain to argue with you on this one. Do whatever makes you happy. Just note that I disagree with you, and that I agree to disagree.
Lunarmodule
Enlightened
JS and Luna,
I enjoy your interaction and appreciate your in-depth knowledge of electronics, which is many orders of magnatude greater than my own. I scramble to take notes on the fine technical details you gentlemen discuss and find it informative. However, to some degree its a little comical that you cannot, as JS pointed out, just agree to disagree and instead engage in a bit of verbal swordplay over the most minute details. All for the greater good but its unnecessary to generate any negative feelings over it.
I'm almost afraid to ask why ohmic approximation of a filament is wrong, only thing I can figure is it dosent reflect the dynamic change of its electrical characteristics over time as the filament heats and changes physical properties. With my limited experience I have to rely on educated guesses to navigate my way sometimes.
With all that I have come to learn about incan I am continually amazed at the durability and function of a tungsten filament in a glass envelope. Reading descriptions of the startup event of a bulb with its huge inrush current leaves me in near disbelief that anything could withstand such extreme short term stresses and still work reliably. Amazing.
I enjoy your interaction and appreciate your in-depth knowledge of electronics, which is many orders of magnatude greater than my own. I scramble to take notes on the fine technical details you gentlemen discuss and find it informative. However, to some degree its a little comical that you cannot, as JS pointed out, just agree to disagree and instead engage in a bit of verbal swordplay over the most minute details. All for the greater good but its unnecessary to generate any negative feelings over it.
I'm almost afraid to ask why ohmic approximation of a filament is wrong, only thing I can figure is it dosent reflect the dynamic change of its electrical characteristics over time as the filament heats and changes physical properties. With my limited experience I have to rely on educated guesses to navigate my way sometimes.
With all that I have come to learn about incan I am continually amazed at the durability and function of a tungsten filament in a glass envelope. Reading descriptions of the startup event of a bulb with its huge inrush current leaves me in near disbelief that anything could withstand such extreme short term stresses and still work reliably. Amazing.
Lunarmodule
Enlightened
JS,
I am curious about re-rating the MN21 to determine how much bulb life I may be sacrificing with my overdrive. The problem is I dont know what to plug in as an accredited design value, since Surfire keeps their specs proprietary, for good reason I would imagine. They have a great secret recipie in the MN21 to be certain. I have only measured inline current and not direct bulb voltage. I used the data from Brock's Flashlight Page as a basis for design values. What figures do you recommend to plug into the formulas you provided? Thanks for those, by the way.
I am curious about re-rating the MN21 to determine how much bulb life I may be sacrificing with my overdrive. The problem is I dont know what to plug in as an accredited design value, since Surfire keeps their specs proprietary, for good reason I would imagine. They have a great secret recipie in the MN21 to be certain. I have only measured inline current and not direct bulb voltage. I used the data from Brock's Flashlight Page as a basis for design values. What figures do you recommend to plug into the formulas you provided? Thanks for those, by the way.
JS said:
The problem with an ohmic approximation is that it is wrong.
Period.
You need to use the re-rating formulas. But I disdain to argue with you on this one. Do whatever makes you happy. Just note that I disagree with you, and that I agree to disagree.
So you believe an ohmic "approximation" is not suffient here when dicussing a current a small temperature change. Oh well lets jump to emperical then.
I just measured the MN21 with 2 LG2400s(used a bit but with open terminal voltage of 7.98--full charged normally to 8.32v)
I=5.04
E=6.58
Here I'm getting 33 watt at 6.58volts
So now we now have enough information to used thve rerating formulas and your 6.86v since behand we never had enough info to accomplish this because you rejected Brocks data.
Ir = (Va/Vd)^0.55 * Id
Ir=(6.86/6.58)^.55*5.04
So using my measurements as the baseline and your voltage, that would be 35.38W at 6.86V/5.156A
Using brocks measurements would put your 6.86 at 5.22A, a little closer to 36 watts
Now if you still think that thermistic changes will play an appreciable role, you still can apply ohm law to to determine the resistivity of the tungsten filament.Just compare the approimation assuming ohmic and the rerated ones using your 6.86v and you will notice a mild difference of only 100ma. What is weird is that the rerating given a lower calculated resistance at the higher voltage which doesn't concur with reality.. Nor do my
measurements compare with your farout technique to come up with 4.9 to 5A via assumed L/w, 100% pack utilization and runtime.
PS Gee you are an *** sometimes, with me and AWR etc.... Also the lockups are because of the quote ubb code, I haven't been able to get thru since yesterday because of that
The problem with an ohmic approximation is that it is wrong.
Period.
You need to use the re-rating formulas. But I disdain to argue with you on this one. Do whatever makes you happy. Just note that I disagree with you, and that I agree to disagree.
So you believe an ohmic "approximation" is not suffient here when dicussing a current a small temperature change. Oh well lets jump to emperical then.
I just measured the MN21 with 2 LG2400s(used a bit but with open terminal voltage of 7.98--full charged normally to 8.32v)
I=5.04
E=6.58
Here I'm getting 33 watt at 6.58volts
So now we now have enough information to used thve rerating formulas and your 6.86v since behand we never had enough info to accomplish this because you rejected Brocks data.
Ir = (Va/Vd)^0.55 * Id
Ir=(6.86/6.58)^.55*5.04
So using my measurements as the baseline and your voltage, that would be 35.38W at 6.86V/5.156A
Using brocks measurements would put your 6.86 at 5.22A, a little closer to 36 watts
Now if you still think that thermistic changes will play an appreciable role, you still can apply ohm law to to determine the resistivity of the tungsten filament.Just compare the approimation assuming ohmic and the rerated ones using your 6.86v and you will notice a mild difference of only 100ma. What is weird is that the rerating given a lower calculated resistance at the higher voltage which doesn't concur with reality.. Nor do my
measurements compare with your farout technique to come up with 4.9 to 5A via assumed L/w, 100% pack utilization and runtime.
PS Gee you are an *** sometimes, with me and AWR etc.... Also the lockups are because of the quote ubb code, I haven't been able to get thru since yesterday because of that
Lunarmodule,
I am curious about re-rating the MN21 to determine how much bulb life I may be sacrificing with my overdrive. The problem is I dont know what to plug in as an accredited design value
That is why I haven't a clue as to why JS posted the use the rerating formulas. He should realize that no base values are given (because he rejects brocks) . It didn't make sense in the context of the post so I had to use ohmic approxiation.
Just use brocks data and 1 for the Ldesign. This will give you a relative life lost
I am curious about re-rating the MN21 to determine how much bulb life I may be sacrificing with my overdrive. The problem is I dont know what to plug in as an accredited design value
That is why I haven't a clue as to why JS posted the use the rerating formulas. He should realize that no base values are given (because he rejects brocks) . It didn't make sense in the context of the post so I had to use ohmic approxiation.
Just use brocks data and 1 for the Ldesign. This will give you a relative life lost
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