I had to swap my trolling batt saturday after running down my cranking batt. I'm not sure I hooked them back up properly. it's a hand controlled digital motorguide. 24 volt. I have two red cables and two black cables. when i look on the motorguide site at the diagram they only show one red and one black on the 24 volt diagram....if i remember correctly mine had a red and a black going to batt 1 and a red and a black going to batt 2 with a jumper going from positive on one batt to the neg on the other batt. thats how I hooked it back up. afterwards when i'd get over half power it would slow down, I know one of the trolling batts was almost dead because I had tried to start the engine with it and it wouldnt turn it over so i had to use the other trolling batt. maybe that's why it kicked down the prop speed. hope this all makes sense. out of the water the prop turned at full speed with no load on it. any help is greatly appreciated!!! thanks