# How to safely limit current for DC12v 30a?

I am plating my vias with electrolysis, and I need to safely limit the current so it doesn't go over 30 amps.

The power supply I'm going to order is, you guessed it, 12V 30A.

I've calculated the need for a 0.4r resistor, but good luck finding a 0.4r resistor rated for 360+ watts.

I'm following this guide, unfortunately they don't mention how many volts you are supposed to use, they only give you a calculation for the current. (They do say 0.25v, but only when you are first putting the board in the bath)

Is there anything else I can do? Hopefully that doesn't break the bank?

I just had an idea while writing this, would using 4 100 watt, 2 ohm resistors in parallel work(to get it to 0.5r)?

• You could look for a constant-current power supply. Maybe look for LED drivers, since LEDs are also driven based on current. – immibis Apr 23 at 0:39
• I added a link to the power supply in my main post, it says its for LED's, but I don't see anything about constant output. On another note, I was using my adjustable bench PSU, running only 5 amps through it, but the wires started smoking. I was going to change the cables to something that could handle it, but was worried it may damage my PSU, even without the smoking cables. Would a bench supply fall under the constant-current type supply? – LittleRain Apr 23 at 0:46
• If your bench supply has a current limit knob, then it will be safe from damage from overcurrent because that's what the current limit is for. (just because the actual supply is safe doesn't mean your wires won't catch fire though as you found out) – immibis Apr 23 at 0:57
• Ok thanks a lot immibis. – LittleRain Apr 23 at 1:12
• Assuming you've ordered that beast, which is a wide compliance-current constant-voltage power supply, you should now search for a DC-DC Constant Current 30A Converter to provide what you really want: a wide compliance-voltage constant-current power supply. – jonk Apr 23 at 7:21