Does the green light ever quit blinking . I had a friend tell me his would eventually be green and not blinking and that was when a battery was fully charged.
I have been using mine for over a year and when it goes to blinking green I unplug it

When it goes to solid green it stops charging and is just monitoring. If charge drops it comes back on then will shut off again once it goes solid.

Mine go solid green within a few hours..every time. You might check water levels in the batteries and check for proper, clean connections at each battery and terminal.

Don't unplug it. It should have a maintenance feature that when the battery starts loosing charge it shoot a little juice to it to keep it fully charged. Only time it shouldn't be plugged in is when your fishing otherwise soon as you return plug it back in till your ready to go again.

The blinking green is a maintenance mode once the battery is fully charged.