Hi my alternator produced this whining sound but its charging at 2,500 rpm with 13.1 volts with Aircon how long will this last before i replace it with a new one? The problem now is am at the trails about 190 miles away from home. Will this make it home?
Usually that indicates that a bearing is going bad and the alternator needs to be replaced. It's really impossible to tell how long it will last at this point. The problem is that once it fails it usually will seize and then everything on the belt that runs it will also stop working. That often includes your power steering and water pump.
So if you choose to continue on, be prepared for it to fail.