Soltaker Posted March 20, 2007 Report Share Posted March 20, 2007 I have a 13.8V / 25A power supply that I would like to use in testing. I'm looking to drop the amps from 25A to around 8A while keeping as much voltage as possible. I've thought about using a resisitor, but it would have to be in the neighborhood of a 200W / 1.725 ohm resistor to work. Any suggestions on how to pull this off without needing a huge resistor? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 20, 2007 Report Share Posted March 20, 2007 The power supply doesn't provide 25A all the time. It provides only as much as the load needs.If you reduce its output current with a resistor then a load will receive a reduced voltage.13.8V at 8A is a load resistor of 1.725 ohms. Its power dissipation is 13.8V x 8A= 110.4W.If you connect two 1.725 ohms resistors in series then each one will have 6.9V and each will dissipate 6.9V x 4A= 27.6W.Maybe you want to LIMIT its max current to 8A. An electronic circuit might be added to its circuit to do it. Attach its schematic. Quote Link to comment Share on other sites More sharing options...
Soltaker Posted March 20, 2007 Author Report Share Posted March 20, 2007 Thanks for the reply, I guess my math was wrong. I was using P = V squared / R which would be 13.8 squared (190.44) / 1 = 190.44W. Yes, I want to limit the maximum amperage running through so that it doesn't get all the way up to 25A. Having a way to vary the max amps would be really nice. I'm currently experimenting with Peltier modules and I don't want to fry it by putting too much amperage through it. It's probably just me, but I don't see any link to a schematic that would limit the amps to 8. Quote Link to comment Share on other sites More sharing options...
ante Posted March 20, 2007 Report Share Posted March 20, 2007 Attach its schematic. ?? Quote Link to comment Share on other sites More sharing options...
Soltaker Posted March 20, 2007 Author Report Share Posted March 20, 2007 See told you it was me. I misread the thing about the schematic. :) I'll post one as soon as I have one. Quote Link to comment Share on other sites More sharing options...
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