We bought this boat last season and it was stored with the battery in the boat, so no maintenance over the winter. It is a Delco m24mf Voyager deep cycle/marine 620AH battery. We do not have any accs. like trolling motors or amps on stereo to draw additional amps. After charging it is acting like it is bad so it goes downtown for a load test. If it is a goner what is a good battery for this application?