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Adaptation of a PC PSU.

Modern computers require quite a lot of power (electric it is) to do their trick's. At the same time we need PSU's (PSU=Power Supply Unit) to power our chargers when preparing for tomorrows flying.  Since the PC PSU's are made in the thousands, they are dead cheap compared to other PSU's (it's just a fact; things become cheaper if a lot of them is made in customized production lines).  The issue is just that you have to do some adaptation to be able to use such a PSU to power your charger.  First of all it won't turn itself on when connected to the mains (without a trick), and secondly the output terminals are suitable for PC mother-boards, graphic cards and disc-drives, they simply do not match your charger.  Below I describe how to do such a conversion, the PSU used to explain it all is a fairly modern one that are capable of delivering 60A at 12V.  It's quite obvious really, but you must remember that this operation will void any warranty on the unit.

This is the label of the PSU that I modified, 60A @12V is quite OK.

This is the connector for the mother-board of the computer, when the mains are connected one wire will go live with 3V or so.  To activate the other outputs this wire must be connected to the blue wire.  The 3V wire on this PSU is the green one, please use a voltmeter to verify your unit.  BTW; the ground wires are the black ones.

 
The connection between the green (3V) and the blue wire is done inside the PSU.  Take care to isolate the connection (any other connections you make also). 

Internal cabling, the black wires are ground and the yellow are for 12V.  It's a good idea to group 3-4 black and 3-4 yellow wires when connecting your custom cabling.

 

 
This is all the original wiring that I simply cut off and threw away.  
 I have put Deans connectors on all my charges so Deans it is also on the outputs from this PSU. 

Testing by charging 3 10S LiPo batteries at 7A charge current simultaneously (usually this requires just above 60A at 15V).  I checked the voltage while all was operating and even with this slight overload it had only dropped to 11.8V.  An additional good feature with the PC PSU's is that the cooling fan is a big one that operates almost soundless.

 

 

Newer and more powerful chargers require higher input-voltage to be able to deliver their maximum power. Two PSU's can be connected in series to get 24V.  To do this two things must be done :   1- The ground connection on the input to one of the PSU's must be disconnected.  2-The chassis of the two units must be isolated, during operation there is 12V between the two chassis.