1st P7 mod 4 me

or 3

Left one is a 1 AW "C" cut down by Mirage_Man with a P7 HAIII DHS heat sink "C" by H22A and a CSXOI P7 by PhotonFanatic.

Middle one is a 1 AW "C" cut down by Mirage_Man with his "D" to "C" sleeve,P7 HAIII DHS heat sink "D" by H22A and a CSXOI P7 by PhotonFanatic.

Right one is a 3 "D" with ElektroLumens P7 O-Sink and a CSXOI P7 by PhotonFanatic.

All are direct drive.
Did them today,and now my other friend wants a 2"D" P7.

What buck/converter should I use?

depends on what batteries you will be using in the 2D mag, primaries? NIMH? or Li-ion?

thomashct said:

depends on what batteries you will be using in the 2D mag, primaries? NIMH? or Li-ion?

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Since his work will buy the batteries @ Home Depot, primaries.

should work with direct drive or a 8x7135 driver, but don't expect it to be anywhere near as bright as any of the P7 light you have got shown :shakehead.

I wouldn´t count on the P7 getting enough juice to even light up from 2 D-cell primaries...
My Wichtel-driven 2D-Maglite won´t turn on using 2 primaries...

Think you'll need to use 3 C's and perhaps mod the tailcap. Follow Stefan's thread for multi-mode driver instructions https://www.candlepowerforums.com/threads/195358. The 7135 driver should work well with 4.5 to 3.5 volts supply. Not sure about alkaline battery discharge but this setup should only draw about 1 amp average from the batteries. Think I'll make one up myself.

Where did you get that cut down blue C-cell Mag? That is sweet.

The 8*7135 that Kai sells is a buck regulator, so that won't work. 2D Alkalines don't have enough voltage and 2D Li-Ion's is too much. Scattergun is right about 2 Alkalines, I'm afraid you just can get enough juice out of that kind of battery to drive any regulator to the proper level. With 2D Alkalines in direct drive, estimating from SSC's pdf, you'd only get about 160 lumens at 3 volts. Actually their graphs haven't changed since the original J voltage series. The I series you are using is 0.25 volts lower so it would be dimmer yet.

I had D cell Alkalines in my 3D Mag for a while. If they're giving your friend the batteries for free, they only last for a half hour, but they do work. Or is it a matter of your friend has this 2D he wants you to mod? You could stick 3 NiMH C cells with a PVC spacer and a modified tailcap spring in a 2D Mag. Or does he have to use the free alkalines? Using 3C Alkalines in a 2D Mag can't deliver enough juice so that's out too.

What about 2 AW Li-Ions and a buck regulator?

I'm too slow. I agree with shakeylegs about 3C NiMH in a 2D Mag using direct drive.

My battery draw figures were off. I was using 1 amp to the emitter rather than 2.8. Battery discharge can range from 2.7 to 3.5 amps. Not sure how alkalines will respond. Nimh's might be a better choice although they are producing barely enough voltage for optimal performance by the 7135.

Al Combs said:

Where did you get that cut down blue C-cell Mag? That is sweet.

Or is it a matter of your friend has this 2D he wants you to mod? You could stick 3 NiMH C cells with a PVC spacer and a modified tailcap spring in a 2D Mag. Or does he have to use the free alkalines?
What about 2 AW Li-Ions and a buck regulator?

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http://www.yourlightsource.com/inc/sdetail/239

Thanks for the info,I was thinking about 3 C's also.I'll ask him if he has NiMH batteries.

I didn't realize you could still buy C-cell Mags in any color besides black. Thanks 3rdrock.

I've read people say it's possible to fit 3C's in a 2D light. I never actually tried it myself. But if your friend has to buy something anyway, maybe Sub-C's would be better. At 43mm long, 3 of those are only about a quarter inch longer than 2D's. You still need the PVC sleeve, but they would fit without a tailcap mod (Dremel or oven-cleaner). Maybe just a wee shortening of the spring.

Al Combs said:

I didn't realize you could still buy C-cell Mags in any color besides black. Thanks 3rdrock.

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All the Home Depots in central & north Florida have pewter 2 "C"s,you might want to check your local HD.

The 2D to 3C is one of my favorite P7 direct drive setups. Use PVC pipe to take up the space for the C cells. I haven't tried Alkalines, but have in a 3D setup and runs pretty well. Amps will drop after use, but light is still plenty bright.

Love those 3 lights, I've been meaning to make a cutdown 2C. Time to PM Mirage Man. Thanks for sharing!