Could tell that the alternator solved problem right away, running voltage was back up around 14.67 from 12.01, engine ran better, accelerated better, mileage improved, below zero starting improved ( battery was good, no need to replace ). Easy to install after loosening three bolts, 30-45 minutes including belt (belt probably not needed but had 300,000 miles). First replacement alternator in this 2006 Commander, had probably been bad for a few months, internal heater fan speed changes on acceleration, headlights very dim, battery light started dinging regularly and battery drained causing alternator replacement.
What kind of vehicle do you drive? 2006 Jeep Commander