shunted digital ammeter

[Dunderberg]

I bought a couple of digital LED voltmeter / ammeters for my Bronco II and the old F-250.

Wiring them seems more of a challenge than anticipated!

The wiring diagram shows to install the shunt between the Load(s) and the Negative battery terminal.
I'd prefer to install it between the Positive battery terminal, and the alternator & positive feeder wires throughout the chassis BUT exclude the starter motor.

If it is installed on the Negative side, then I can't really exclude the starter (the amperage from that would probably fry the shunt).
The sheetmetal body, frame, and drivetrain are all grounded together. If I somehow isolate the drivetrain (starter motor), then I also am excluding the ignition system and 4wd 'Touch Drive' unit.

Any ideas? Anyone know of a "positive shunt" Volt-ammeter?

Geoff

 

[Robert Mangrum]

Does the shunt have an amp rating on it? The stunts we install would fry if you ran positive through them. The smallest we get though are 400 amp rated. Which should handle your starter fine. I assume that the starter gets ground straight off the block. So eliminating it would be an interesting endeavor. Shunts are not that expensive and normally are universal to work with multiple meters. So you could always purchase a bigger shunt if yours isn't rated high enough.

 

[Curious Hound]

In most cases, it should not matter if the actual shunt is in the positive side or the negative side of the system. The actual shunt is nothing more than a very precise, low value resistor. The meter is measuring how much voltage is dropped across that resistor. It's simple ohms law. More current across the resistor = bigger voltage drop. E = I x R. The only shunts I've messed with were rated around 350amps. I would still want to isolate it from the starter motor. But, it shouldn't hurt.

Of course, always follow the directions and pay attention to the ratings of the actual device you are using. Sometimes, you can get further info from the manufacturers website.

1st gen Rangers used an ammeter/shunt to monitor their electrical system. The shunt was in the outout of the alternator.

https://www.therangerstation.com/tech_library/EDiagrams/files/diagram_charging_1983to1985_1.JPG

 

[Robert Mangrum]

The meter interface for my Czone monitoring system gets its internal ground from the 2 wire shunt feed. If we hook them up positive it blows the fuse on the meter. I guess I phrased it wrong this morning. The shunt itself doesn't care polarity.

 

[Curious Hound]

The meter interface for my Czone monitoring system gets its internal ground from the 2 wire shunt feed. If we hook them up positive it blows the fuse on the meter. I guess I phrased it wrong this morning. The shunt itself doesn't care polarity.

It all depends on the exact device used and the connections the manufacturer provides. That's why I closed with "follow manufacturers instructions."