Here is a write-up on a one-wire alternator. At the bottom of the information is:
How to wire to your vehicleAll that is "required" is to run a heavy, at least 10 gauge wire from the BAT terminal to the positive (+) post of your battery. I would suggest you connect it through the AMP meter. Depending on the information you want, there are a couple of ways to wire the meter. The first, and preferred, is to measure the charge/discharge of the battery. The other is to measure alternator output. The alternator output also includes the current draw of the lights etc. of the vehicle. Alternator output is best measured by voltage not current. The charge/discharge method tells whether the battery is charging or discharging.
Here is the schematic shown in that article. This has worked well for me for 13 years (with ammeter working fine, the battery charges, no external voltage regulator, and the alternator "excites" at about 800 rpm).
