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This is quite efficient since all of the power from the battery is delivered to the LED. Lithium-ion batteries conveniently provide a decent voltage without any further modification. If you apply the correct voltage, you don't need a driver at all. And for longer cycle life, do not charge over 4V.17mm linear regulator driver wchips and microprocessor For example do not allow the battery to discharge below 2.8V. Home Depot has good prices on Coast flashlights.īe sure to check out Battery University to learn the optimum way to charge a Li-ion battery.
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You are probably better off buying one than making one. I also like their $150 AR25R and am seriously considering buying one. They must be using top of the line Li-ion batteries.īatteries last 3.25 hours 1200 lumens, length=17", weight 1.4 kg,b beam distance 2762 FT / 842 M. Getting 3.25 hours of 1200 lumens out of batteries is not easy. This shows these guys charge $170 for the Li-ion batteries and mini USB charger. The non-rechargeable HP314 is only $330 powered with four D cells. The flashlight I'd like to have is the Coast HP314R, a $500 rechargeable.
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#Led flashlight driver circuit series#
Source: LED Series Resistor CalculatorĪ good flashlight is very difficult to make. You cannot beat 94% with a switcher current source. At the start of the discharge curve at 4V the efficiency is 83.5%. That will yield an average efficiency of 94%. The mid-point in the discharge curve is 3.5v, so that is the value to use when calculating the resistor. And LED luminous intensity will drop also. The current limiting resistor is not as bad as one might think. Finding a driver with higher amperage will be very difficult. For example the TI TPS63030DSKR but it has a maximum of 800 mA.
#Led flashlight driver circuit drivers#
There are LED drivers made especially for a single Li-ion cell. At 1500mA, 4.65W, your are driving it hard so the efficacy drops to 130 lm/w. My choice would a Cree XP-3G, the most efficient (185 lm/w) high power white LED. You did not specify the part number of lumens for your LED. I would flood the bottom side with copper and drill a lot of vias near the LED to connect the top and bottom thermal copper.Īn 18650 battery is a very good choice for powering an LED.Īn LED with a 3.3 V f works very well with an 18650 and resistor. I would flood the PCB top side with copper for the XP-G3's thermal pad. I would then sandwich the PCB between two plates of copper or aluminum with a hold large enough for the LED and lens. Qty 5 with Immersion gold plating over 2 oz copper $66 Qty 5 with Immersion gold plating over 1 oz copper $39 It is much more planar (smoother) than HSAL and will help a lot with thermal conduction between the PCB and heatsink. copper, 2 sided FR4 with the immersion gold plating would be a good option for thermal management. If it is in your budget I would use 2 oz. These guys do a very good job and small PCBs under 4" x 4" (100mm x 100mm) are very cheap, $5 for 10 PCBS. LEDil is a very good company.ĭatasheet: LEDiL PRODUCT DATASHEET C11249_STRADA-S This spot lens is made for a Cree XP LED. Now that I know the V f (3.06) at max current (2 Amp) of the LED and the max voltage is ≈4V.ĩ7 resistors that will work: Digikey 0.47 3W+ Resistors Voltage will drop rather quickly to less than 4V. With a max 2000mA where V f = 3.06V 85☌.Īn 18650 at 2000ma will have a max of 4V. I will need to back off on the 0.13Ωn resistor. The Cree's XP-G3's V f will be ≈3.1V, likely less.