bbaker2001 wrote:
would the 50 amp be sufficient . I don't think I ever pull 50 amps at 1 time
does the shunt just attach between the ground going to battery
The shunt typically does go between the ground and the battery. All loads should connect (directly or indirectly) through the shunt if you wish to measure the current they consume—so typically the connection between the shunt and the battery should be the only connection to the negative battery terminal.
50A would generally be adequate for the house loads of a good many RVs, possibly excepting a few things that you may or may not have or care about measuring: a largish inverter (over, say, 250W, when used in combination with other house loads); the starter motor for a generator (my Onan 4KW starter rates at somewhere around 90A), and possibly charging if you have a sufficiently beefy converter or a very good charging setup from the alternator of a motorhome and the battery is sufficiently discharged.
Many of these digital ammeters are only capable of measuring current in one direction, so you have to choose between showing discharge current or charge current. (This is determined by which way you hook the sense wires up to the shunt.) Some are capable of bidirectional measurement, perhaps only if they have an isolated power supply for the meter electronics.
