Yes I agree it is time for new batteries. However a dying charging system may have cause the batteries to fail. Once those new batteries are in check and monitor the charging voltage for a few days. Voltage should never dip below 13.2 volts while plugged in and should always register as full on the monitor. Get a small voltmeter if you do not have one.
Might help to post what equipment is charging the battery. Is it a simple converter? Or do you have an inverter-charger? Either way post the make-model number for best answers. If you don't know where to look ask the battery guy to look. Some are good but don't expect too much if he looks confused.
