Verify that the small red wire to rear of alternator is still there. It goes to a post at about 1 or 2 o'clock as you view the rear face of alternator. OEM wire has a hard plastic cover over the terminal, as I recall. That wire is in addition to the alternator's fat red wire, about 5/16 inch diam., and the alternator ground wire which is usually at about 7 or 8 o'clock on the alt's rear face. Follow the ground with your finger to make sure it's not torn loose at it's other end.

Assuming those are all there, check the instrument cluster's red warning lights that should illuminate just before you crank the engine to start it. I believe there are six of those. If less than four are working the alternator will not charge. Those bulbs receive 12V from the battery and then feed to the alternator. If too many of those bulbs are burned out the alt doesn't get enough of that 'exciter' current, and the alt won't charge.

If you need to replace those small bulbs - removing the cluster isn't too hard but on a '92 you have to make sure you disable the airbag first. I'll leave those writeups for others if you answer back that you need the information.
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.