My 3 Red Top batteries have stopped hold ing charge. This occurred sudenly, in the past 2 weeks. The BOOST switch gets them up to about 12.8 volts, but turning the BOOST switch OFF results in rapid decline of the voltage to 12 volts or less within 5 minutes or so.<br/><br/>I am assuming that one or more of these 2.5 year old batteries is defective. Optima says a bank of...