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Just a flesh wound
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Discussion Starter · #1 ·
I have a DIY set-up with two Cree XRE Q4 LED's, and a 1000mah Buckpuck. I run it on full with a 7.2 volt battery pack. Should I use a 9.6 volt pack instead? The 7.2 blows away my old light, but would I get longer burn time with the 9.6, or more brightness?
 

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Just a flesh wound
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Discussion Starter · #2 ·
More information

The battery pack is 7.2V NiCd with 2200 mah rating. When charged it shows 7.95 volts on the meter. I broke one of the leads on my potentiometer so I cannot run lower than 1000ma until the new one arrives.

I am not too clear on how the Buckpuck works. Is it giving me 1000ma with this set up or is it limited to the forward voltage chart as shown on the Cree website?

Without the driver I have 7.95 / 2 = 3.975 for each LED, but I have to remove how much from the original 7.95 with the Buckpuck at 1000ma?

Thanks for the replies.
 

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don't quote me on this....
but i think each emitter needs 3.7 ish volts and you need a further 2 volts for the buckpuck (unless you get a boost which ups the voltage)
so thats about 9.4V
the voltage will not increase the runtime, the mAh rating of the battery pack will
 

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As the voltage to the buckpuck increases, the amps to the buckpuck decrease. So if you increase the battery voltage, the runtime increases because the buckpuck will draw a lower current. It’s the total capacity of the battery in Watts and the circuit load in Watts the will determine run time. Watts being the Volts multiplied by the Amps.
 

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Just a flesh wound
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2,373 Posts
Discussion Starter · #5 ·
Thanks for the input

SkUG and Snowdog, thanks for the help. I will get the 9.6 and compare with the 7.2. I will post pix for both options.

I must say that the 7.2 is super bright... so what will the 9.6 do?
 

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Bandolero
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nix

Prophet Julio said:
SkUG and Snowdog, thanks for the help. I will get the 9.6 and compare with the 7.2. I will post pix for both options.

I must say that the 7.2 is super bright... so what will the 9.6 do?
From my experience with buckpucks, the increase in voltage will not increase the brightness of the light. The buckpuck is a regulator, stepping down the voltage so that it only puts out as much power as is needed by the LEDs.
 

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aka RossC
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notaknob said:
From my experience with buckpucks, the increase in voltage will not increase the brightness of the light. The buckpuck is a regulator, stepping down the voltage so that it only puts out as much power as is needed by the LEDs.
Agreed. The buckpuck generally needs about 1 V more than Vf to stay in regulation so you would be right on the limit with a 7.9v pack off the charger. As your pack drains, the light is probably dimming as the circuit goes into direct drive. This will probably be slow enough that you may not have noticed.

With a 9.6V pack, you will stay in regulation throughout the charge cycle and so you will get a constant output.
 

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ocean breathes salty said:
NEVER!!! If you have a spare battery... you have an excuse to make another light :yesnod:
So, I have ordered 2 lipos at 11.1 V 4Ah
Today I got thems and 4 R2 & maxflex3. Have learned here that such configuration will not work.
I have ordered another few lipos at 7,4V, but they are on the way, so have to wait to look how my leds shines

With that 11.1V I will build another lamp. Can You suggest me some good configuration for a such voltage? Which driver for MCE?:confused:
 
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