5x Cree and 4x Li-Ion, best battery arrangement?

[effulgentOne]

I'm thinking of running 5x Cree off of 4x Li-Ion, and would like recommendations for the battery arrangement.

Each LED will have it's own buck circuit with an Vin range of 3.7-9V. Because I have an odd number and want to be able to turn them off and on individually, I'm pretty sure I'll have to run them in parallel.

However, the battery arrangement could be 2S2P or 4P. I was thinking the higher voltage would be better because the stock switch probably can't handle 4+ amps at 3.7V. On the other hand, it would be nice to be able to run an odd number of cells if needed. Would the regulators be significantly more efficient at 3.7V than 7.4?

Any input would be appreciated, thanks.

 

[yellow]

more "intelligence" means more things that can fail.

leds in series
cells in series
taskled Maxflex or SandwichShoppe's Shark+Remora as driver

PS: there are mot too many drivers that can run a led good from a single Li-Ion (I only know of the Flupic)

 

[kurni]

more "intelligence" means more things that can fail.

leds in series
cells in series
taskled Maxflex or SandwichShoppe's Shark+Remora as driver

PS: there are mot too many drivers that can run a led good from a single Li-Ion (I only know of the Flupic)

+1

I tend to keep it simple; preferably 6 LiIon series to drive 5 Q5 in series with BuckPuck / nFlex / bFlex. FiveMega has 6AA>2D holders.

 

[effulgentOne]

more "intelligence" means more things that can fail.

leds in series
cells in series
taskled Maxflex or SandwichShoppe's Shark+Remora as driver

PS: there are mot too many drivers that can run a led good from a single Li-Ion (I only know of the Flupic)

by "turning off individually" I meant "physically cut power to each of the drivers for a rudimentary form of dimming," I don't think there would be too much complexity in that (a DPST switch with one position being all five on, the other being one, maybe)

I had been trying to avoid the shark as it's more expensive, but it would be much more efficient to dim on the shark board, than to run only some of the LEDs, and it would simplify things, it would be a known quantity, etc.

For all those reasons, I think I'll take your advice, with all 4 cells in series.

Many thanks to all who replied.