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BY KIM DOHERTY
If you are going to make the move to electric powered flight, you are going to need a 12 volt DC power supply to charge your Lipos on the bench. While you can use your car battery, I caution you that it is not a deep cycle battery and if you are using it continuously to charge large power packs it may wear the battery down.
Word OF CAUTION !!! Disclaimer: The information presented should not be considered a "HOWTO" article, but merely a documentation of my conversion process. Modern PC Power Supplies can produce high output current levels that may cause internal overheating in the PS or damage to devices connected to them. Any individual attempting their own conversion is cautioned to carefully research their PS specifications and to be mindful of the associated voltages and power. DO NOT work on your opened power supply with it plugged in!!!! Please do a lot of research prior to attempting this modification and have the necessary testing equipment to ensure safety. Do not attempt to de-solder components if you do not have previous experience doing so. Just clip the wires and cover with heat shrink tubing. ***************************
The modification to the power supply consists of identifying the correct voltage leads, eliminating non-essential leads, completing some sensing circuits (brown wire to orange and green to black) to allow the power supply to turn on and providing a load to the +5v circuit to simulate a drive load. This load is provided by adding two 10 watt 1 ohm sandbar resistors in series to the +5v circuit. You can see these in the pictures mounted to the heat sink with twist ties.
I chose to remove all wires (yellow, red and black) and replace them with 12ga. Deans wet noodle wire. This required desoldering all of the extra leads and drilling larger mounting holes in the appropriate places. (Note: should you insist on going this route, make sure you use a uni-bit to drill the holes!)
Total cost for the project: 550 watt twin fan 110/220v ATX type PC power supply $60.00 Total: $77.00 You can also purchase a lower wattage AT style PC power supply for quite a bit less. ($20 ->25) If you will be travelling to a country with 220v power, the ability to handle 220v is important! Here are three very good links to complete articles on this conversion. http://www.reckerclub.tripod.com/id105.html
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