hi gang
i want to direct drive a luminus pt54 red emitter ,3.2 3.8vf X 9a plus, with a tenergy ifr26650e 3.2v X 3300 mah with a max continious dischsrge rate of 6.6a.
so my question is: when using the above combo will the pt54 led only draw a max. of 6.6 amp from the lifepo4 battery or will it take more amps from the baatery than that?
Chances are it will pull more current than 6.6 amps but the battery will heat up and will have less capacity. However it may be smart to wait for a answer from someone more experienced before you do the build.
i believe the max pulsed discharge on this battery is 9 plus amps
run times will be short , 5 to 20 seconds and in below freezing temps.
I have 2 Nichia Phat Light LED’s - direct drive running off A123 Lifepo4 18650 cell. The diode pulls up to spec and not beyond ,
reason why A123 cells work well in direct drive applications. I haven’t used Tenergy cells and im not familiar with nominal operating specs. Although i belive they are quality cells and very well possible A123 underneath. The Nichia Phat Light LED’s can pull twice the amount with spec output rated at 1100 lumens ( a bit to much red led for me) and the host gets slightly warm after 5 minutes. Otherwise a perfect linear drive cell. Blue at 500 lumens is one of my favorites
Maximum listed PT54 amps is 16a per data sheet. The highest I have pushed one while DMM testing is 14a. Running these at high amps non pulsed will shorten the lifespan. How much is a guess, may cut the lifespan to 1000 hours or 20 seconds. I have been using the Tenergy 3.2V 1300mAh 4.16Wh LiFePO4 (IFR18650P) and with my heavy copper leads DMM get 8a+ @ the tailcap direct drive. This is in a 501b with modded P60 OP reflector and solid C110 copper pill/heat sink. The longest runtime straight was 2 minutes due to heat. I haven’t gone for broke and have charged the cells when there was detectable dimming which was probably after 6(?) minutes of accumulated runtime. Will offer this… Do the copper wire mod to the spring mod cuz at these amperes springs turn blue. BTW I did perfect the mosfet tape switch for high amps. Everyone who mods smokes emitters, hard to put the blue smoke back in.
the ifr18650p that Willie mentions has specs of max discharge continous of 10a and a max pulse discharge of 20a.
for the ifr26650e specs are 6.6a and 9.9a for as above.
so does that mean that the 26650 will not allow a high of a discharge rate as the 18650?
thus less amps to the emitter?
The cell will probably put out quite a bit more current than 9A… 9A is the safe discharge rate. Beyond that, the cell might be damaged. The current drawn by a direct drive LED would be determined by the LED’s Vf rating. LiFePO4 cells are 3.2V nominal (max charge voltage is 3.6V). That tends to be a good match for most LEDs. And LiFePO4 cells have a very flat discharge curve. 90% of their output power is spent between 3.3V and 3.1V
The A123 cells are beasts. A 4S pack of the 2300 mAh 26650 cells will start a car 20 times in 20 below 0 weather (my flashlight that uses them has a jumper cable connector)!
They can dump over 200 amps into a short circuit. I’ve seen them charged in under 45 seconds at 100C rate (200+ amps). Professional driver. Closed course. Don’t try this at home.
Is that the light you aren't allowed to talk about or another one? :P
It’s the other one. Uses a 5000 lumen Bridgelux array. I am thinking of upgrading it to a 12,500 lumen device using that KD 9xXML driver. Or maybe just mod my driver into a boost converter for the higher output voltage. The battery pack is a 4S2P (boost driver) or 8S1P pack (sort of direct drive) of A123 M1 cells.
Oh, and I can talk about the 180,000 and 540,000 lumen lights… but then I have to kill you and eat your brains. 0:) Yummm! Tasty brains! Arrrrgh, drool, tasty brains.