Surefire B90 direct drive Cree Q5?

Big Bad · Aug 19, 2008

Want to put a Q5 into an old surefire 8X I have using the stock B90 battery. Even if I use a board the low battery voltage should mean it drops out of volatage regulation right away, but what about current regulation. If I use 800ma board, will it still regulate down to 800ma or what? Not sure what the battery produces with a full charge, do I even need to worry about current with this match up?

Thanks guys, I've got lots to learn about the electronics part of all this.

LukeA · Aug 19, 2008

3 cells is too much to driect drive. An 800mA buck board will give 800mA to the LED until the voltage of the battery is lower than the Vf of teh LED at 800mA. Then it will go direct drive until the battery voltage is too low to fire the LED's junction.

NiCd packs don't have very much power compared to newer types.

monkeyboy · Aug 20, 2008

The GD driver from the Sandwich shoppe is what you need. It's a boost-buck driver designed for this purpose. When Vin > Vf it works in buck mode and when Vin < Vf it works in boost.

BTW: NiCd is capable of high power but has less capacity.

Big Bad · Aug 20, 2008

monkeyboy said:
The GD driver from the Sandwich shoppe is what you need. It's a boost-buck driver designed for this purpose. When Vin > Vf it works in buck mode and when Vin < Vf it works in boost.

BTW: NiCd is capable of high power but has less capacity.

This sounds like the plan. Thank you.

Surefire B90 direct drive Cree Q5?

Big Bad

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LukeA

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monkeyboy

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Big Bad

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