Help with shunt ammeter
I just got one of these from ebay: I am trying to read V and Amps while charging a battery on the bench. I have the shunt attached to the negative battery post, and the charger clamped to ...
Forum Discussion
I can't find the meter you purchased on Ebay, so my comments may not be quite right.
I am assuming the shunt develops 75 mV at 30 A. That means it has a resistance ofI 0.0025 ohms. This is too low to measure with most multimeters.
About all you can do is measure continuity of the yellow and black wires to the shunt incoming and outgoing. If all four terminals show continuity, disconnect the meter from the shunt and connect a different multimeter to the shunt metering terminals. At 7 A, the multimeter should read about 18 or 19 mV. If the multimeter doesn't read anything, the shunt has a problem.
To check the meter, you would need a 1.5 volt D battery and a 1500 ohm potentiometer. You could then connect the meter to the negative and wiper. Starting with the lowest setting, increase the resistance by turning the pot and the meter should respond.
I haven't looked at battery charger output on an oscilloscope. In the back of my mind I am wondering if the charger output is clean DC, or if it is something like a half sine wave, or heavy ripple. The waves have could affect readings.
I am assuming the shunt develops 75 mV at 30 A. That means it has a resistance ofI 0.0025 ohms. This is too low to measure with most multimeters.
About all you can do is measure continuity of the yellow and black wires to the shunt incoming and outgoing. If all four terminals show continuity, disconnect the meter from the shunt and connect a different multimeter to the shunt metering terminals. At 7 A, the multimeter should read about 18 or 19 mV. If the multimeter doesn't read anything, the shunt has a problem.
To check the meter, you would need a 1.5 volt D battery and a 1500 ohm potentiometer. You could then connect the meter to the negative and wiper. Starting with the lowest setting, increase the resistance by turning the pot and the meter should respond.
I haven't looked at battery charger output on an oscilloscope. In the back of my mind I am wondering if the charger output is clean DC, or if it is something like a half sine wave, or heavy ripple. The waves have could affect readings.
