There really is not a good wat to put an amp meter on these tractors. If you put it between the alternator and the battery, you only see what the alternator is putting out. If you put it between the battery and the switch, you only see what the accessories are drawing.
I suggest adding a voltage meter. You can run a wire from the accessory side of the switch, and you can tell if you have a good battery and if it is charging properly based on the voltage.
If you have to have an amp meter, then you need to move the acc power from the back of the starter motor to the B+ on the alternator, then bput your amp meter between the alternaot and battery. That will change your power flow, and the meter will show true charge/discharge.
HF actually have some cheap ones i've used in the past, and i've never had an issue with them.