I have a 1998 Islander with a single OX66 Yamaha 250HP. with two batteries. Recently the battery indicator started blinking at 12 volts and below indicated. At speed (25) knots or so it blinks, and sometimes at trolling speed as well. Occasiaonly I can get the voltage over 12.6 volts. I was reading the manual trying to troubleshoot, and it seemed to indicate either a bad battery, or a volateg regulator. Has anyone else run into this, and do you have any suggestions on how to troubleshoot?