Posted on 2016-09-20
I have a small project on the goal to de-rust some old car parts.
I have setup a small Electrolysis tank for this and I am now trying to get my head around the relationship of Volt to Ohms and Ohms law etc.
I need to provide it with a 12v supply and allow it 2-300mA. I have either a power adaptor which can output 300mA or a big 12v battery.
If I connect the leads direct to the tank it draws around 5 amps. I need to limit this to 2-300mA so I thought I could use a resistor. I put a 100ohm resistor in line with the positive lead and whilst it did limit the current, it also get very hot which I didn't think was right. It also only allowed around 2v through when measured.
What is the best method to limit the current off the battery?
I want to do this outside without the need for mains power but if I did use a mains adaptor 12v 300mA power supply I presume it would not do any harm to the adaptor? The draw of 5A from the battery concerned me but I gather the adaptor would push the 300mA rather than let a much higher load be pulled through it.