Smallest practical form factor for a P7 light

Ask the title suggests, what would you guys consider to be the smallest practical form factor for running a single P7 emitter in the upper end of its output range (approx 900 lumens, if my understanding is correct) for a period of around one hour? Forget about flood vs. throw characteristics for the moment - and the obvious effect that will have on reflector size. I'm thinking more of the minimum battery requirement to achieve this level of performance.

I would like to know this as well, though I'm not necessarily interested in the smallest form factor possible. I wonder what are the forward voltage and upper current specifications of the P7. This should be fairly easy to figure out with that information.

Running a P7 on 1 x 18650 would get you between 45 minutes and 1 hour of runtime, depending on the forward voltage of the emitter, since they seem to vary slightly.

This is a popular swap:
http://www.dealextreme.com/details.dx/sku.6177

ampdude said:

I would like to know this as well, though I'm not necessarily interested in the smallest form factor possible. I wonder what are the forward voltage and upper current specifications of the P7. This should be fairly easy to figure out with that information.

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I hear you ampdude. Maybe it would be better to just consider different battery types and pose the question along the lines of, at 900 lumen output, what would be a realistic runtime for a single 18650, what would be possible for two 123As, or for three 123As, or for a single rechargeable D cell, etc. etc. Perhaps we could even address the differences we might see with direct drive versus regulated, boosted, etc.

I see Drew is already helping us out.

you have this one with a P7 : http://www.dealextreme.com/details.dx/sku.12271

driving current = 2.8 A
VF = 3.6 V

see all specifications and datazsheet here : http://www.seoulsemicon.com/en/product/prd/zpowerLEDp7.asp

JP

The smallest cell you could use for 1 hour runtime would have about 12 watt hours of capacity, so something slightly bigger than a 18650.

If you're happy with a bit less light, then a 18650. Otherwise something like a LiIon C-sized cell would be required.

freedom2000 said:

you have this one with a P7 : http://www.dealextreme.com/details.dx/sku.12271

driving current = 2.8 A
VF = 3.6 V

see all specifications and datazsheet here : http://www.seoulsemicon.com/en/product/prd/zpowerLEDp7.asp

JP

Click to expand...

Thanks, JP. I did see that one. Please correct me if I'm wrong, but the impression I'm getting from the early reviews that are out lead me to believe that the emitter in this light is not being driven at full capacity. I may have that wrong though.

Fallingwater said:

If you're happy with a bit less light, then a 18650. Otherwise something like a LiIon C-sized cell would be required.

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With the proper electronics, would it be possible to get something close to 900 lumens from a single newer LSD type NiMH C or D cell?

freedom2000 said:

driving current = 2.8 A
VF = 3.6 V

Click to expand...

3 x CR123A would be perfect for this, and then a big reflector. It believe that kind of flashlight would have a nice size and form.

At PF10, Data had a reflectorless Spy005 (mule?) with a P7 in it. Pretty small form factor there.

MSax

HKJ said:

3 x CR123A would be perfect for this, and then a big reflector. It believe that kind of flashlight would have a nice size and form.

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Or a pair of 18500s.

HKJ said:

3 x CR123A would be perfect for this, and then a big reflector. It believe that kind of flashlight would have a nice size and form.

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I have to agree with this. 3xCR123 would be perfect for this. The cells can take the power draw and the whole package would not be too much longer than a 1x18650.

2x 18500 or 2x 18650 body (I prefer this last configuration).
Large and deep reflector for throw with some spill.

I have received the Eastward YJ-XAQ5 (1x 18650 body) today from KD and it's areal monster thrower ! It has large bezel/head, reflector is large and deep, and overall very thick (good for heat dissipation).
Build like a tank. Good host for P7 (I'm not expert however).

This flashlight coupled with a P7 and 2x 18650 body would give maximum load for the P7 with decent runtime.

But I think we need to wait a little yet to obtain efficient drivers for the P7.

With 2x 18650, P7 will be driven @2,8A for ~90 minutes.
Excellent runtime regarding to the output delivered.
Coupled with High-Mid-Low-Strobe (100%-20%-2%-Strobe) capable driver, it would be very versatile.