Originally Posted by jameswilson29
I disconnected my solar panel controller when my boat was hauled and reconnected it for my trip down the Bay last week. In the summer, my batteries will charge to above 14 volts with the panel and the alternator. Last week, they were down in the mid 12s voltage. Is there any problem leaving them connected to the solar panel all winter?
No problem until it becomes a problem.. By that I mean leaving it connected is fine provided you have a controller that does float but if the panel becomes occulded with snow or ice the controller can actually kill the battery.
These controllers almost always have a small mV draw to them for "self power".. When you disconnect batteries EVERYTHING must be 100% disconnected. Often the easiest method is to break the neg connection to the battery bank. If you disconnected the solar panel but left the controller connected to the battery bank you likely sucked it down..
Here's a prime example of a "disconnected" bank that is not really appropriately "disconnected". The large neg leads have been removed but on the house bank a small back neg wire for the bilge pump is still connected. This boat has an "electronic" bilge switch (self consumption about 0.01A or 1.68Ah's per week) that type of load can drain the batteries over time if that small wire is not also disconnected.... Be sure to really "disconnect"..