New LED Work Like Project...

Hi Guys new to the forums here but have been reading here and there on different topics...I am kinda a DIY with just about every thing i do...like to keep myself busy doing different things...I had a couple questions on making my new LED work Light. I wanted to make this thing two way compatible in that it can either work on A/C or D/C power. I know how to hook it up A/C but not so sure about D/C. I ordered a 100w LED to do this with. What I would Love to do is have it be able to work off my 20v dewalt batteries which just incase your not familiar with them despite the name are 18volt. Im really not sure what I would have to do to be able to hook the battery up to it. I would imagine there is enough power in the battery for it but im really just not sure what i have to look for to do this. The other thing was I have an old CPU heatsinc that i plan on using for this thing. Im not entirely sure where i have to wire the fan into. Not sure if I just have to use a resister off the same spot that i wire the LED onto power supply or what not. Any Feed back would be greatly appreciated.

Also If it would help here are the units i bought so:

http://dx.com/p/prime-100w-8000lm-led-emitter-metal-plate-pure-white-42806

http://dx.com/p/3-0a-100w-power-constant-current-source-led-driver-85-265v-47306

Thanks,
Mike

For your current equipment, I would suggest using an inverter, but most auto inverters wont support 18v input. If you use a 12v battery rather than the 18v dewalt pack, an inverter will work fine though. A 12v battery will also allow the 12v PC fan to be run directly, but the rpm's will decrease as the battery drains. Alternatively you can use a 12v output ac/dc adapter which you will also plug into your inverter. This would give the fan a constant 12v rather than slowing down as the battery drained.

Another strategy for this entire setup would be to use a boost driver. The AC power adapter would be a ac/dc converter which outputs a similar dc voltage to the charged battery pack. For example, a taskled hyperboost driver would require the battery voltage to stay above 25 volts for the input current to stay below the drivers limit of 5 amps. 25 volts on an 8 cell lithium pack would be 3.125 volts per cell. At full charge the pack would be at 33.6 volts, which should be below the LED's operating voltage. It is a requirement of the boost driver that the input voltage be below the LED voltage, or regulation wont occur. Since the LED operating voltage is "32-36 volts" It might mean that the LED couldn't be dimmed to its lowest levels on a fully charged pack, but this is probably a non issue. Finding a 130 watt 30 volt power adapter is a bit tricky. Astrodyne makes some but they are $75-100 depending on whether you go open frame or external. As you see this a bit more expensive than using a 12v battery and an inverter to feed an AC LED driver.

Yet another strategy would be to use a buck driver such as taskled's hyperbuck. This could be fed from two 6S lithium packs wired in series for 50.4 volts, and the AC/DC converter could be 48 volts DC. A >130 watt 48 volt power supply is a bit cheaper at around $60, for example a Meanwell GS160A48-R7B.

As for the fan outputs from a DC source, a DC/DC converter which outputs at your fans voltage is a good way to go. A standard pc fan is 12v, but they also make 48v, 24v, 5v fans, etc., which can allow them to be used ideally in many different setups. For example a 5v fan can be used with a single lithium Ion cell and a boost circuit. Some dc-dc converters have wide input voltage ranges such as the Recom R-78C12-1.0 which supports 15-42v input and outputs 12v. The R-78HB24-0.3 has 24v output but supports 36-72v input which is suitable to a 12s lithium ion pack and would regulate down to 3v per cell. You would need a 24 volt fan with this, of course. ADDA makes a wide range of PC fans of different sizes and voltages, some of which are water resistant.