Digital Panel meter

Hi Simon,
I too had problems trying to measure current via a 50amp shunt with a digital meter.
While my panel meter was not from Oatley's it appears to be similar.

What I found is: measuring the tiny voltage (a few millivolts) across a shunt while the meter is powered from the same voltage source, eg. car battery, did not work. there was always a noise reading, despite tinkering with fully shielded cables from the shunt to the meter.
What did work in the end is to use a different type of digital panel meter for the shunt. One that had fully floating inputs, eg. it was powered by its own 9V battery and NOT from the car battery.
So I have now two meters, one that reads volts and another that reads the amps flowing thru the shunt. There is a switch that selects which meter is on, one at a time only otherwise the above problem occurs (since I used the same sensing wire for volts and amps). I have another switch that selects readings from the main or the aux. battery.
I hope that helps.
Klaus

Oatley also offer a little kit which converts the supply voltage to a floating voltage. This works well until there is a large temperature variation (ambient) it seems the components (or at least the ones I used) are prone to varience with temp.

Otherwise it is a good way to get around this problem.

Hi Guys,
Thanks for the tips, I will tool around with this again during the week.

Cheers Simon.