As others have said, 14VDC is ok.
A lead acid cell (your battery is made up of 6 cells) has a theoritical voltage of 2.2VDC, this gives a theoretic open circuit voltage of 13.2VDC for a "12 volt" battery. The voltage you see at the terminals of a fully charged battery in good condition will always be between 12 and 13VDC, once you connect a load (lights etc) the voltage will drop down to the notional 12VDC. To charge a battery, you have to overcome the batteries own output voltage, i.e. if your battery is a bit flat and has an output of 11.8VDC then you will to have a charging voltage higer than 11.8VDC, as the battery voltage increases as it charges, you require more voltage to continue the charging process, i.e. 14VDC + to get the battery up to its 13.2VDC.
All lead acid batteries will handle more than their rated voltage other wise you couldn't charge them. The real killer of lead acid batteries is the charging current that they are allowed to draw. The rule of thumbs is that a battery should be charged with a current of 10% of its rated current, i.e. a 10Ah battery should be charged at 1 amp. Like all things electrical, excessive current results in unwanted heat, and it is this heat that "boils" the battery dry. If you are having trouble with your battery getting excessivly hot ( it will get warm, but not that hot that you can't touch it), the easy solution is to turn on your head light. This will apply load to the electrical system and reduce the amount of current that the battery can draw from the charging system.
CJ
