Combine in parallel to get the required capacity, then series 4 banks together to give nominally 12V.
Ideal for Second/house battery and engine cranking.
 
SPECIFICATIONS
3.2V-400Ah
Voltage 3.2 V 
Nominal Capacity 400 Ah @ 0.3C
Weight Approx 13.6kg
Dimensions 450 x 71 x 281(H)mm
DC internal  resistance (max)     <1.0 mΩ 
Operating temperature 0°C to +45°C
Storage temperature -20°C to +55°C
SOC window 10% > 90%
Charge type CC/CV
Quick charge current 400A
Quick discharge current 800A
Standard discharge current 120A
Standard charge current 120A
Max operating discharge current 1200A
Max pulse discharge current (<10s) 4000A
1000A Discharge capacity >90% capacity
Minimum Voltage 2.5V
Maximum Charge Voltage 3.65 V 
Life cycle @ 0.3C, 80% DOD, 2,000
Ceramic membrane technology.
Flame retardant housing.