16.7-20v? Is this common? This is not an disagreement or a start of an argument; just an honest question.
Most 12v auto batteries seem to have a lower recommended charging voltage (13.8-14.4v seems to be common) and a maximum charging voltage (12v Optima batteries have a 15-15.5v maximum voltage and a warning that even at this voltage the electrolyte will boil/evaporate, the relief valve will open, and battery life will be reduced).
from Optima "When used with a properly regulated constant voltage charging system (such as an alternator), the OPTIMA battery will normally not produce hydrogen gas. Occasional gassing can occur when charging at higher voltage levels or in extreme high temperature conditions. In automotive applications this typically will not happen if the alternator/regulator stays below 15 volts."
