So you've got a voltage drop of 1v from the alternator to the battery. You need to find a poor connection that is causing this. Measure the voltage, with the engine running, from the alternator case to the battery negative. Then, measure the voltage, with the engine running between alternator + output and battery positive.
Which ever one gives you the 1v - this is the line to check out for poor connections. Most probably a poor earth from engine to vehicle or subframe.
Good luck, logical measurements will find it !