It goes to one side of the ammeter. The other ammeter connection is the junction point for wiring to the voltage regulator "Bat." terminal, the ignition switch, and possibly the headlight switch. When it's wired that way, the ammeter will accurately indicate current flow in and out of the battery. During normal running, the charging system provides current to operate all the electrical demand, and the leftover current goes through the ammeter to recharge the battery.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!