5pcs ACS712 30A Range Current Sensor Module Detector ACS712ELC 5A 20A 30A Amps Amperage (30A)...

These work quite well and are fairly accurate. All five read the same under test but the offset voltage was closer 2.55, not the 2.5 spec'd. Calculating the measurement voltage, it worked out to match the inline DMM almost exactly. I did not check the frequency response since my application is 12VDC. My concern for others is with the high current connection. It could be a source of failure or even fire. The connector used is typically rated for up to 10 amps, not the 30 amps the chip is capable of measuring. I removed the connector, drilled out the holes, scraped away the solder mask and bent the wire toward the chip and soldered it. I soldered the wire as close to the chip pins as possible since I didn't trust the copper foil much either. I am guessing it is 1oz, not the 2oz copper which would be more common for this application. 12 gauge wire is about the minimum for 30 amps. I have not fully loaded it yet but I suspect the direct wiring will hold up. In all, when you need something to measure higher currents in a hurry, this is a great little device. Being galvanically isolated means you can also easily measure the high side of a DC bus. Eventually I'll make my own board likely with a TI TMCS1107 instead of the ACS712 chip, but for now this keeps me going.

3 of the 5 did not work - specifications say no current should produce Vcc/2 and voltage out should change by 0.1V/amp. Two of the five had no current output less than 1.5V with Vcc of 7 volts and one had no current output of 1.8 volts, but voltage did not change at all with load of 1 amp.

It purports to be capable of measuring 30A, but its terminals are far too small to accept 30A (SWG 12). If your soldering skills are up to it you can replace the terminals and it should handle the current. Another issue is the lack of mounting holes - you will have to figure out a safe and secure way of mounting it (you want to mount it on the neutral line if possible). Otherwise it seems to work okay.