New to forum. My first outboars eng. 200 HP Yamaha,89, after runnung with both batt. for 2hrs come back to lift and she wont start. Both batts. run almost out. What chargers the batt. when the engine is running. Familiar with inboards only. Any help would be appreciated. Thanks
<br /><br />The alternator consiste mostly of the flywheel and the coils under it. Current passes thru a rectifier/regulator on it's way to the battery. A few things can cause the rectifier to fail. Connecting the battery backwards, corroded and/or loose battery connections, interrupting the current flow by turning a battery switch while the motor is running. Another possibility is that one of the batteries is shorted and dragging the good one down. If that's the case, you'll usually notice acid leaking from the bad one.