1.5 amps 7.6 volts

Wow that five er heats up fast!!
I ran it direct drive with a Lithium Ion 7.2 1450mAh batt for about 30 seconds. Thats about all I felt safe with. I just did a reading on the voltage and amperage. It came out 7.6 volts 1.5 amps.
That's my punishment zone for the evening.

Interesting. I get 1.55A using 3x123s...

As fast as it heated up - I'd say ya gotta bring bring 5 pounds of metal along for the ride. It's more than a hand warmer...more like a cigerette lighter. IMO - A D cell holder with a large slug -o - metal in it won't cut it for very long at that kinda juice.
Not that this will necessesarily stop me from using that kind of power. I've got one in the works for two five watters using this power source. They will be under driven the majority of the time with a momentary switch for full effect used in very short burst. There will be a 1 watt in it also for general purpose use for those times when ya want to make a night of it, and 3 Nichias for those long long long excursions.
It's gonna be rather small too.
Shorter than a MiniMag...Fat as a D cell.
And It'll make ya laugh when ya see it.

Pi_314...
That's my kind of design!!
I have also begun to add "Boost" options to my designs. I can't wait to see it.

Recharged the 7.2 1450 mAh.
And let er rip.
Got 8.4 volts at 2.2 amps.
It got ugly quick.
30 seconds later, and I now have an LED that's at least half dead. Two of the dyes bit the dust, but it's not a total loss. The LED is slated for a Palight with little or no heat sink. It will still be impressive.