I have a solar charger on bat 1. When I start engine, I switch the panel to ALL so that I can charge both bats. When I raise the sails and turn off the engine, I usually dont turn off the switch to the batteries. If i dont, the bats are struggling to get the engine started. Do you think this is an alternator issue or does the solar panel reverse charge the batteries when cloudy or dark out?
Side question, does being connected to shore power have any affect on charging the batts?
The short answer is we don't have enough information to tell you anything.
*What wattage is your panel?
*What size battery is it feeding?
*Does it have a controller?
*Does it have blocking diodes?
*How is the solar panel wired in?
*Where is it placed on deck?
*How big, in Ah's, are the battery banks?
*Have the batteries been tested/how old?
*How big is the bank you are paralleling it with?
*How is your shore charger wired?
*What turns on your shore charger?
*Have you checked the voltage AT THE BATTERY TERMINALS with the engine both OFF and RUNNING?
*Same with the shore charger?
*What is the voltage difference with the engine OFF and ON?