Why no P7 or MC-E that takes AA?

GrnXnham

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At least not that I've found.

All P7 or MC-E flashlights use 18650 or CR123A?

Looks like Fenix is making one that takes 8AA (TK40) but doesn't someone make one that takes 4AA or less?
 
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richardcpf

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Why no P7 or MC-E that takes AA?

The same reason that a spotlight doesn't take D cells. P7 and MC-E are high consumption LED emitters, they work better with high capacity batteries. Running high power flashlights with small cells will result in short runtime, faster battery change, less practical.
 

jusval

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Actually there are many Mag mods using 6AA or 8AA holders with P7 emitters. Many 18650 are actually lower amp hour rated than some Nimh AA batteries.
 

Alan B

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At least not that I've found.

All P7 or MC-E flashlights use 18650 or CR123A?

Looks like Fenix is making one that takes 8AA (TK40) but doesn't someone make one that takes 4AA or less?

The P7's take 3.5-3.7V at 2.8A for full specs. Alkaline AA's don't go there unless you series up a bunch and use a switcher to trade the extra voltage for extra current. Some P7 lights only use 2.0A but even this is too much for a few alkaline AA's. NiMH is another story, but not too many manufacturers want to make lights that won't work with alkaline AAs and require NiMH AAs. It confuses the customer and kills their sales potential for larger quantities.

The runtime of a P7 with 3 NiMH AA's at full power is pretty short.

If you want a short P7 light for 3 NiMH AA's get a 1D cut-down M@g and put a P7 and heatsink in it and use a 3AA carrier. If you want multiple levels add a d2Flex. How-to's are available here on CPF for this.
 

etc

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Yeah but you need 3-2500 mAh AAs to match one 2500 mAh 18650 in total energy.

Yes you do and the problem with that is, what exactly? AA works in everything, 18650 is a bizarre single purpose, sometimes dangerous cell that works in nothing else.

(I know I am being devil's advocate as I use them also but FWIW)

If all your devices run on AAs and you want to simplify logistics, and simplify period, then sounds like AA is a winner?


OK, I do realize this is no P7, but FWIW:

3xAA FM body with M30 next to SF 9P with M60. Surefire-like power on cheap and readily available Alks, or stick Eneloops in it. Or L91s.

M302.jpg
 
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yellow

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because both led are simply not on the market for long enough... :rolleyes:

be4 the led revolution it would have needed some years or more till somethng "new" was built in,
now its smoe weeks to 1/2 a year ...

let the makers a tiny bit of testing time.
 

electric sheep

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18650's are superb for energy density and protected cells are not dangerous. Alkalines can leak .
 

Alan B

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At least not that I've found.

All P7 or MC-E flashlights use 18650 or CR123A?

Looks like Fenix is making one that takes 8AA (TK40) but doesn't someone make one that takes 4AA or less?

Four Alkaline AAs cannot handle the energy delivery required by a P7 or MC-E. If they did make one it would not work well or it would be operating the LED at low power.

The rule of thumb for AA Alkaline power delivery is 1000 mA at about 1.2 V average. This is 1.2 watts per cell. The P7 requires approximately 3.5V at 2.8A or 9.8 watts. Thus approximately 8.2 cells are required to handle the power delivery rate. Note that at this delivery rate the capacity of alkaline cells is pretty low - ie their life is poor. Over about 300 mA the capacity of AA alkaline cells drops considerably compared to their low current capacity. For high current applications NiMH, NiCAD or Lithium AA cells are significantly better. In this case three NiMH, NiCAD or Lithium AAs can run a P7.

Ref: http://en.wikipedia.org/wiki/Alkaline_battery
 

ace0001a

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Well actually a P7 or MC-E is more efficient running at lower power than any single-die emitter available at the moment in terms of total light output per unit of energy consumed. You could still get a good runtime out of them running on 4 AAs or less if you're not expecting to LED to run at 2.8A and 800 lumens. Flashlight manufacturers could make such a flashlight, but whether there is actual demand for such a setup over anything else they already make now is probably where the debate is. It probably won't be cheap either as we can see by how much the Fenix TK40 retails for.
 

Alan B

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Well actually a P7 or MC-E is more efficient running at lower power than any single-die emitter available at the moment in terms of total light output per unit of energy consumed. You could still get a good runtime out of them running on 4 AAs or less if you're not expecting to LED to run at 2.8A and 800 lumens. Flashlight manufacturers could make such a flashlight, but whether there is actual demand for such a setup over anything else they already make now is probably where the debate is. It probably won't be cheap either as we can see by how much the Fenix TK40 retails for.

Underdriving a quad LED can be very efficient, but the cost is very high compared to using a single die driven hard, and the small improvement in efficiency is difficult to make a profit on (sell for a much higher price).
 

neoseikan

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Underdriving a quad LED can be very efficient, but the cost is very high compared to using a single die driven hard, and the small improvement in efficiency is difficult to make a profit on (sell for a much higher price).

In fact, it's still profitable if the efficiency is high enough to get less heat and longer runtime. They might be important to a mini light. Kurapica installed a MC-E on his Spartanian II, and got a very very flood beam. We think this light can have more than 200 lumens.
 

Alan B

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In fact, it's still profitable if the efficiency is high enough to get less heat and longer runtime. They might be important to a mini light. Kurapica installed a MC-E on his Spartanian II, and got a very very flood beam. We think this light can have more than 200 lumens.

It is only profitable if the customers are willing to pay for the extra LED costs. No problem here on CPF but since a P7 costs about 5 times as much as an XRE it is hard to justify the cost in an underpowered application to the general consumer market.
 

jasonsmaglites

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great thread. a 2aa p7 would work great. picture a fenix l2d q5. it draws almost 1200ma on turbo mode. the q5 is much less efficent at 1200ma than it is at 300ma. if you sent 1200ma to a p7 or mce, it would be a good 1/3 brighter than a q5 at the same power level. it would be driving each of the 4 led's at 300ma, very efficent! if you so desired you could turn the power up to 1500ma and it would make a nice difference. 1500ma to a q5 isnt much more brightness than at 1200ma.

im with you, i'd love to see a mce or p7 in a quality 2aa flashlight. single aa, well, thats just ridiculous. hear us out fenix. build us a l2d mce
 

GrnXnham

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This is why I like posting a question on this forum.

I got responses with lots of helpful information rather than being attacked for being an idiot and not knowing the answer in the 1st place.

Thanks for the answer everyone.
 

Alan B

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great thread. a 2aa p7 would work great. picture a fenix l2d q5. it draws almost 1200ma on turbo mode. the q5 is much less efficent at 1200ma than it is at 300ma. if you sent 1200ma to a p7 or mce, it would be a good 1/3 brighter than a q5 at the same power level. it would be driving each of the 4 led's at 300ma, very efficent! if you so desired you could turn the power up to 1500ma and it would make a nice difference. 1500ma to a q5 isnt much more brightness than at 1200ma.

im with you, i'd love to see a mce or p7 in a quality 2aa flashlight. single aa, well, thats just ridiculous. hear us out fenix. build us a l2d mce

1/3 brighter is hard to see, and they would have to charge about $40 more for the light.:oops:
 

jasonsmaglites

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true, but that is on the same power level. my theory is that it could take more power whereas the single die could not.

plus, who wouldnt want 1/3 brighter for an extra $20 or so. and thats not even crediting the price of the old led.
 
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