[eagle]

All voltage regulators on alternators are not created equal. Some maintain the battery voltage at 13.8, some at 14.2. Foreign cars, especially from 20 years ago, ran lower voltage on the regulator. They would maintain a battery that was never allowed to run dead, but a dead battery should be charged more than that to return them to deep capacity. It's estimated that each time you deep discharge a lead acid battery, you are going to lose at least 10% capacity. If the battery sits dead for a long period you can lose 50% or more. Its a good idea to put a trickle charger on a battery that's been dead, leave it on for 24 hours+.