I'm not sure if this belongs here, so I apologize if it's in the wrong place, I couldn't find a place for general wiring stuff.
Anyway I picked up an amp meter from an ebay seller "Asia Engineer" and it comes with a shunt and some instructions. The instructions are pretty clear, but it says that you cannot measure both voltage and amperage from the same source using these meters. You also cannot power them from the same power source, and you especially cannot measure amperage and current from the power source running the meters.
I've also purchased a couple of DC-DC isolators so that these meters can be powered in my car(a car is only a single power source afterall)
I've talked to the seller, and using the isolators the meters can be put in my car, but I'm now left wondering about the measurement aspect of it. The sellers english isn't great and he seems to have trouble understanding me at times.
I'm going to measure current from the alternator, the amp shunt will be bolted directly onto my alternator post, and I was going to measure voltage from the battery.
Would this be considered measuring voltage and amperage from the same source?