BSIDE ACM91 Digital Clamp Meter 1mA AC/DC Current True RMS Auto-Ranging 6000 Counts Meter Hz Temperature Capacitance Live Check V-Alert Low Impedance Voltage Tester

This is a very decent clamp meter for the handyman and hobbyist. Its accuracy exceeds my expectations for such a low cost meter. This cheap meter doesn't replace a pro grade meter such as a Fluke, but for casual use around the home, does it really matter if a reading is 11.4 V vs. 11.3 V?What I like about this meter is its 1 mA resolution for DC amp readings using the clamp. For comparison, I also have an Extech 380942 clamp meter that I bought for $400 around 17 years ago. The Extech still retails for $400. The $400 Extech has higher accuracy specs than the $50 BSIDE ACM91, but the differences are slight.I spot checked several DC and AC current readings using the clamp at low currents (for example, around 25 mA DC, 130 mA DC, 330 mA DC, and 160 mA AC). The clamp-based readings between the Extech 380942 and the ACM91 essentially matched, differing by no more than 1 or 2 mA. The ACM91 was stable at low DC amp readings using the clamp and drifted a lot less than the Extech.Some caveman reviewers sounded like they never bothered to read the user manual and then blamed operator error on the meter. Some of them didn't plug in the test leads properly. One reviewer didn't understand that clamp readings only work with one phase (i.e. one wire) at a time. One operating detail that should be obvious is that the clamp only works when the test leads are removed. If the test leads are still plugged in, the clamp will give no reading.The most important thing about the DC clamp amp meters is they use a Hall effect sensor to detect DC currents. The manual specifically instructs the user to press and hold the zero button for 2 seconds to zero out the reading before taking a DC amp reading with the clamp. Some users didn't zero the meter and got wildly wrong DC amp readings and then blamed the wild readings on the meter.I'll add one further detail not mentioned in the manual to help give better DC amp accuracy when using the clamp. Once you've zeroed out the DC meter, hold the meter in the same orientation when taking readings. Don't tilt it, twist it, or rotate it. Otherwise, changing the orientation of the meter can give false readings due to different magnetic flux through the clamp from the earth's magnetic field when the meter is oriented differently after it's been zeroed.A main drawback is the meter screen is very hard to read. It has a curved protective lens and it's almost impossible to avert reflected light due to the curvature of the lens. A flat surface would have worked much better to minimize reflections.

When the battery in my new car, that only had 149 miles on it was dead one morning I decided I needed an amp clamp to check for parasitic current draw on the battery. After I charged the battery with my battery charger and checked the battery cable, something was drawing 3 Amps with the car, turned off and all the lights out and doors closed, except the trunk where the battery was. I later found out by searching that some of the computer functions of the car stay on for up to an hour. To find out how much current is drawn when everything is asleep would require me to crawl in the trunk with the trunk lid close, and the car shut off and the key fobs in a metal can so the car wouldn’t detect the key fobs and watch the current draw for an hour in the trunk. I am not going to do that since the car has never had a problem since that one time and now I’ve got over 500 miles on it and it stays charged now. Maybe the passenger door was a jar I don’t know. The door does have thick gaskets and if you don’t close it firmly, it does stay a jar. I will keep this in my trunk at all times so I know where it is when I need to use it.

I sometimes find myself searching for power drains in automotive applications, and bought this ACM91 meter primarily for its DC amp-clamp functionality with sensitivity down to milliamps. Since this is a very challenging measurement, I accept the realities of poor accuracy and high noise level. I think it will do what I need.The ACM91 has several fairly specialized functions in addition to the normal AC/DC voltage/current and resistance. For household electrical use, it has two methods of detecting live power wiring. Its "V~Alert" function provides a non-contact voltage sensor at the tip of the clamp. It also has a "LIVE" function that uses only the red probe lead for simple contact measurements. It has a very sensitive DC current function that tops out at 200 microamps, designed to verify operation of the flame detector in a gas furnace. The capacitance mode seems intended to verify motor capacitors, as it has a max of 6,000 uF and resolution of only 0.1 uF. The temperature probe is a thermocouple of unknown type, using a small diameter wire that will probably break quickly in use. If the type were known, a more durable probe could be easily made by the user.I recommend that you perform your own QA testing upon receipt. The first meter I received had a defective solder connection on the red banana jack that created an intermittent connection. The second meter I received had a defective crimp connection (open circuit!) at one of the thermocouple plugs (very strange). I fixed that by soldering it, but I suspect that meter had been returned as well (no vinyl sheet over display), and nobody actually tested the thermocouple probe since such things almost never fail.In summary, I think this will be a very handy meter for household and automotive applications, and a decent value for the price. Just be sure to test everything when you first get the meter.