Here is a quick howto, how to make yourself a power supply for your LiPo battery charger. You will need a used or new computer power supply unit. In a computer power supply you have multiple voltages, but we are interested in the 12V one. There are a lot of wires of different colors, we are looking for yellow ones, which give out 12V.
CAUTION: You will be dealing with some serious voltages. Until the current goes through the DC converter, you have some 220V AC so watch out. Always unplug your cable from the house power socket. If you don’t know what you are doing, buy yourself a power supply.
Here is what you do:
Take some yellow wires and wire them to a connector. This will be your 12V. Do the same for some (the same number as yellow) black ones, that is your negative. These are the connectors you will then plug your charger on. Because, in a power supply unit the 12V voltage is not the primary voltage, we have to wire a resistor to the 5V wire, which is the red one. One easy trick to do here, is wire the red and a black wire to a 12V car light bulb, which will act as a resistor. Now we are almost done. Just one more step, so the power supply starts. You have to short wire the gray and one black wire together. This is the signal which tell the power supply its on. The color of this wire varies from power supplies, so check that the signal is PS-ON. You probably have this written on a sticker on the power supply. Now, when you click the switch, the power supply unit should start: The fan starts to spin and the bulb lights. Check the connectors with a multimeter that you really have 12V.
See the pictures below.
I did some couple of "power box" for my friends on the club.
Just using a cheaper 10$ 220w computer font. I use one resistor of 10 ohm x 10 watts in the 5 volts wire.
Works great and I can put on charger 4 LIPO batteries with 2.2A each and no problem.
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regulated output with thermal overload protection.
*current output depends on a few factors, mainly the amount of voltage you want to drop.
NAM
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Also I suggest putting two +12v wires in parallel, that way it doesn't stress the wire as much.
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other detail. some PSU's have a brown wire shorted out to the 3.3V line on the ATX plug. this is to "measure" the voltage dropout on the main power line (3.3V) btw: most of the power supplies control the 5V line as the main one but the main line is supposed to be the 3.3V
I have at least 2 power supplies of this kind and they are very useful! its just a shame we can't trick them to put out 13.8V mines often only give out 11.5V with little or heavy load (and with load on the 3.3V and 5V lines)
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