easiest way to tell if your alt is getting to the battery, start the jeep, and set your volt meter to read 15 volts, or whatever your closest range is to that, and then put it across the battery terminals. if you're reading anything above 13 volts, change the battery because the alt is putting out and it's getting to the terminals. if not, touch the positive lead to the alt's output terminal and the neg to the alt's case. if you get above 13 there, then your alt is putting out, but not getting to the battery, check your fuses and the cables. if you're not getting power there, then it's either the alt or the field control from the computer.
RIP: '88 YJ 2.5L Ax-5 NP231
Posi-Loked. Herculined. Optima yellow top. 1" Shackle, 2" BDS. Cragar 397's Aussie front.
92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood