I am in the process of making a mains power monitor using a SCT-013-000 CT clamp and an arduino mini, running on batteries. Even though I should be able to get many months of operation from two small AA batteries, would it be possible to use the clamp to harvest power to run the unit forever?
If I'm doing the maths correctly, two 10F 2.7v capacitors in series would keep a unit drawing an average of ~0.1mA, 5.4v->2.7v running for a couple of days even if there is no power usage on the mains wire?
Best Answer
If you want to monitor mains power precisely, you have to measure not only mains current but also mains voltage. When you measure mains voltage you can use a small transformer to power the microcontroller inductively because you already have a connection to both wires of mains. No energy harvesting necessary.