Confused...

[Photodiode]

Dear friends
I'm planning a D Mag mod, and I would like (please) some answers to questions I have.
I'm thinking to buy a D mag with 4 cells -maybe 5-, to power a P7. I 've stuck with the batteries. What could be better choice? A 5 D alkalines, or in this length 4 18650's ? Or maybe a 5 D cell to AA converter? Also if I go for the 18650 (protected), the 4 cells will be in series (that means 3.7x4=14,8 V) or a combination of two in series and two in parallel? I would like also many hours of runtime. Of course I'm gonna need a pwm driver, with -let's say 4 or 5 modes-, and I'm thinking of the D2flex driver. Do you have any recomendations on this mod? Add please If I'm not asking too much, what bin of P7? A D***I emitter or a D***J?
Thank you all in advance
Kon

 

[nailbender]

Three NIMH 12,000 mah with a d2flex makes a long running very bright light. Once you go over 4NIMH or one Li Ion then the D2flex is not enough since it is just a dimming board with no regulation. Three of the above batts will get you clost to three hours of run time.

Dave

 

[ktafil]

Hi there,

I use this buck converter in a 2D-->6AA m@g.
Running the P7 on 2.5Amp gives a battery draw of about 0.75Amp.
2.5Amp is a little under driving the P7, but does not do very much in output.
I did this to increase the battery life.
On 2850mAh cells this is almost 4hours light.
This guy also sells multi mode setting stuff.
In a 4D you could use 6x 5000mAh Sub-C cells wich should give about 6.5hrs of runtime!
Hope you can make a good choice, let us know what and why you choose wich direction to go.

good luck with your built

 

[mudman cj]

If you are going to use a large battery pack, then you can expect it to hold higher voltage under load than a simple 1x18650 direct drive, for example. So, if using that in combination with a PWM driver like the D2Flex, be aware that 100% output mode could overdrive the LED significantly depending upon your particular battery solution and the Vf of the LED. Therefore, I recommend going with the J voltage bin instead of the I.

Li-ion battery packs would have to have all of the cells in parallel for the D2Flex, so they would also require holders. The problem is, you couldn't just use two 2x18650 parallel holders because the holders would be in series and you would end up with 2s2p. This is why you are getting more Nimh than Li-ion suggestions. Three of the D sized Nimh cells would be an excellent choice because of the long runtime and no need for any holders or making a battery pack. Still, I also second the option of using 6 Sub C cells. The Elites have shown excellent self discharge behavior in the experience of several members. This solution would require you to wire the batteries 3s2p. You can have a pack made this way for you. I recommend member LuxLuthor.

When you get the light wired up, take a current measurement and see where you are at 100%. If it is too high, then you can add a resistor to fine tune it.

 

[Photodiode]

First of all I wanna thank you for your replies
From what you 're saying, I think I'm gonna go with 5 D cells like these http://thomasdistributing.com/shop/...html?SP_id=&osCsid=tbb6s6crmkidpc4cr3gv020q41
Of course a Der Wichtel's buck converter with the D2flex driver can drive without problems the P7 emmiter, and in a low power mode I think I will have light for a dozen of hours!
If I go for 4 D cells do I still need the buck converter? My last question is why you are suggesting me sub C cells (which must be smaller than C), and no D cells?
Thanks again
Kon

 

[mudman cj]

You can go with 4 or 5 D cells and a buck converter, but for your originally stated intent then you don't want to use more than 3D cells. Don't try 4 D cells without a buck converter unless you also use proper resistors. The reason for Sub C cells is so that you can fit 6 in a 4D and have good cells that exhibit excellent self discharge characteristics. Think twice before you choose a host bigger than a 4D IMO - but everyone has different ideas of what is useful or comfortable to carry. And the record shows that I also recommended D cells, as did nailbender.