SUPER TECHNICAL ADVICE NEEDED

[BLACKAVAX]

Hi


I'm going to build a flashlight with cree xhp70.2 (12V, 2.4A, 29W).

I want to use 6x 21700 (5000mAH, 3.7V), 2 rows of 3x in series which makes it 11.1V with 10,000mAH. (I want this much energy to run the flash light for 4hrs at about its maximum brightness).

The question is what driver I must use? As the only driver I could find was 6V output while I want a 12V output driver. (I don't want to use 6V output driver as the current double gets very hot)

Anyone can help me in this really appreciate it.

 

[archimedes]

Hello and welcome to CPF

Your post above has been approved, but thread was moved to Homemade/Modified forum

 

[staticx57]

You need to reset what you are trying to achieve. Assuming you had a 100% efficient driver you don't have enough capacity to drive that emitter at 29W for 4 hours. The emitter is asking for 129Wh with a battery capacity of 110Wh. Anyways once you sort out your battery situation you probably want to consider using a buck driver with 4 in series to compensate for voltage sag in the cells.

TaskLED makes some nice drivers

 

[DIWdiver]

If the sticker shock doesn't get you, the TaskLED HBFlex and Hyperboost drivers would do the job for you. I'm not aware of any other boost regulators I'd want to use.

But if you want your 4 hour run time, you probably need 8 cells. In a 4S2P configuration, that would work well for a buck regulator, and would likely have higher efficiency, given the same quality of design and build. You also have options for many inexpensive regulators like the one discussed in the Buget Dive Lamp thread in this same (Homemade and Modified) forum. In this configuration, the regulator input current is 25% lower than with the 3S configuration.