I have an IP 370 (Hull No. 70). Today while sailing with engine off, the charge light on the engine panel came on. It would go off when the engine was running, and come back on again each time the engine was shut off. The engine has been shut off now for about six hours and the light is still on. Start battery is fully charged, alternator seems to be working, and the charger is working while on shore power. Any suggestions on troubleshooting?