>I have always wondered about this.  They should charge at anything over 13.2
>volts, but I assumed there was some "breakover" voltage that was applied
>in excess of the 13.2.  I, too, have seen cars running at 14 volts and above,
>batteries bubbling away.  What are the factors in this choice?  Does
increasing
>the voltage above 13.2v decrease the charge time?  At what voltage will the
>the battery start overcharging?
>
>Anybody know the best voltages for maintaining a charge without overcharging,
>for quick-charging a battery, and for daily driving?  

Batteries will charge at any where from 12 to 15.5 volts. But you are right
about the implications of higher charging. A way we used to condemn
batteries was to put a heavy charge to them and if they went above 15.5
volts the battery is suspect to being bad. If you use a maintenance free
battery you don't want to charge it at a higher rate because you could boil
out some of the acid. A 13.5 volt charge is good to keep the battery alive.
You can charge it at 14.5 volts but keep an eye on the fluid. HTH

 Greetings from Michigan's Upper Peninsula
 Jeff & Jean-Marie Diebolt
 mailto:jdiebolt@up.net