Re: 95 Grand Cherokee shutting off
Put a volt meter over the battery poles and check the voltage with engine off. Fully charged is 12.7V, when at 12.1 its almost fully discharged. If low, charge it first with an external battery charger.
After charging, check voltage (half hour after charging). Should be 12.7V. If considerably lower, then new battery is bad. If ok, start the engine and check battery voltage. Should be 13.5-14.5V. If lower, then its not charging the battery. Or the new alternator is bad, or the voltage regulator.