I recently purchased a Glastron GS279 Cruiser equipped with a 5.7l Magnum 300hp with Bravo III. It is equipped with three batteries, but the battery switch only has settings for 1,2 or both. I tested my batteries with a battery tester and even with a load they still read good (stayed between 12 and 13 with load) but when the switch is set to battery 1 the blower barely runs and the engine will not even turn over, but when I switch to the "both" or the "2" setting everything runs-cranks fine. I was told by a friend that the third battery is only for the stereo since it has stinger fuses on the top of the battery cover but is in the circuit to charge. I have been out already a few times this year and the charger is obviously charging the batteries, yet battery 1 will not crank the engine. Where should I start?
