I just purchased this Rv and decided to replace the 12v batteries as they were 2004 and not holding charge.I have tried hooking up + to + and - to - unsuccessfully.Since I'm not the orig. owner I have no idea if they were orig.6V.I have three red wires the smaller I believe is from the generator like the small black.Then I had connected the two larger red cables to the + of the first battery, connected the- of the first battery to + of second battery with a jumper.Next I connected the large black wire from the carriage to the - of second battery.This allowed the slider to operate but the lifts would not go down? I also questioned which battery would the generator leads connect to and if both larger red cables should be connected together on the first battery? I'd appreciate your help on this.Thank You