The battery’s just didn’t recover sufficiently even when left on charge overnight. It is time to quit messin’ with them and replace both of them.
The one on the left is the supply to the high thrust trolling motor, but it is also the battery backup should something happen to the main starting battery. Both are deep cycle Marine battery’s. My thinking on it is that if we were dead in the water and at the mercy of a storm, we would be wishing we has spent the few bucks it takes to replace both of them.
On Lake Greeson you could shelter in a cove because of the way the lake is laid out.
Lake Ouachita is much larger ( 34 miles long ) and we have weathered 5’ swells on it. Yeh, new battery’s, it’s a no brainer !