Each bank outputs 12 volts meant for individual 12v batteries no larger than a group 31 battery (approximately 130 AH). The Dual Pro PS4 can be used for four 12v banks, up to two 24v banks, one single 36v or 48v battery bank. Typical installation is for 36-volt series system using three 12v batteries for a trolling motor and an additional bank for a starting 12v battery. Another popular installation is for 24-volt series system using two 12v batteries for a trolling motor leaving two 12v banks for starting batteries. [links]