Yes, something around 14v would be good, but...at a certain point you don't want it overcharging as you don't want to boil your battery out...especially a new one. Conversly, too low and it won't recharge....

On the second car...with the apparent buggered up diodes, I checked with the meter from time to time .....to make sure, I was not damaging anything by overcharging, or undercharging and we always got around 14.21. I kept an eye on it, but drove it that way for almost a year before finally switching the alternator itself...and everything appears fine...although I am not sure if continuing to drive a car this way could damage stuff. I guess a person would have to know what purpose the diodes have to be certain. In my case, the dash light bugged me and it does not give one piece of mind with the dash light on all the time, especially since the second car was a gasser.

Don't forget, the diesels don't rely on the battery to stay running, and may run down the battery during the course of the day...then you find out when it gets dark that the headlights are getting dim....and you get stuck in the dark....or you turn it off somewhere and it does'nt have the juice for a restart....could catch a person by surprise, but if the battery light is on...it will come back, and not seem as much of a surprise. With the cost of a battery and being that a voltage regulator is between 20-30 bucks .....it is cheap enough to keep a spare in the glovebox...We do.