[ray_mcavoy]

It's been a while since I've measured one, but the values you posted look pretty close to what I remember. So I think your meter is okay. But like VetteVet described earlier, it's not going to work correctly with the alternator output being re-routed to the batt stud on the starter solenoid. You'll need to return that back to it's original connection point.

Attached is a simplified diagram of the charging system / ammeter circuit. As VetteVet pointed out, it is a common misconception that the battery provides all of the power to the truck and the alternator just charges the battery.

Under normal operation, the alternator supplies all of the power to the truck's electrical loads as well as some current to charge the battery. So I_alt = I_load + I_batt (flowing to the battery). But since the output of the alternator is connected directly to the loads via the main power distribution point, only I_batt flows through the shunt / ammeter. So the meter only indicates the charging current flowing to the battery. This is usually noticeable on the meter after first starting the engine. But as the battery reaches full charge, the charging current drops off and the meter goes back closer to the middle.

In a situation where the load current exceeds the capacity of the alternator, the alternator will provide as much as possible and the battery will make up the difference. I_load = I_alt + I_batt (flowing from the battery). But again, only I_batt flows through the shunt / ammeter. This time it's flowing in the opposite direction so the meter will indicate the battery being discharged. This could be normal if the engine is idling (alternator output low) and there is a lot of load on the system (lights, heater fan, wipers, etc. all running). But would indicate a problem with the alternator if it's happening under higher RPM and/or lower load conditions.

With the output of the alternator re-routed to the starter batt post (effectively the same as hooking it to the positive battery terminal), you now have the battery & alternator connected together on one side of the shunt (instead of one at each end). So any current going to charge the battery will be going direct (bypassing the shunt/meter) and therefore not registering on the meter. While the load current (as supplied by both the alternator and battery) would all be going through the shunt/meter and therefore showing up as a constant heavy discharge.