As correctly mentioned above, ammeters in small GA aircraft can come wired from the factory as showing the amount of current flow going into or out of the ship's battery or the current flow coming out of the alternator. If an analog ammeter is wired to the battery this is sometimes indicated by an ammeter with a zero in the middle and a plus sign to the right/ minus sign to the left.
When we install Electronics International ammeter shunts in our shop, we ask the customer which way they would like the ammeter to be wired, as the STC permits you to choose. I am not familiar with the G3X system, but perhaps it is similar.
On a well equipped J model, with everything turned on (all lights, radios, transponder, pitot heat... ) you should be showing quite a bit more current flow than 7 amps, regardless of the state of charge of the ship's battery.
Provided the battery is well charged, a simple test would be to leave the engine off and turn on all electrical equipment that can be safely operated on the ground and read the current flow indicated on the ammeter.
