Difference between a Series and Parallel
In this image, we show you what the difference is between a series and a parallel setup.
The Parallel setup means that the voltage will stay the same but the AMP Hour will increase by however much the battery added is, in this case, all the batteries in this example are 12.8V 60Ah so the Parallel system is now a 12.8V 120Ah. No balancers are needed when setting up a parallel system.
The Series setup means that the voltage will go up instead of the AMP Hour, once connected the system will now be a 25.6V 60Ah. Note in any series system you will need balancers to make sure the voltage is regulated, in this case, you will need 2 balancers 1 for each battery.
The Series-Parallel setup means that both the Voltage and AMP Hour are affected and will increase, since there are 2 batteries in a series 2 balancers will be needed 1 for each battery in the series, the parallel batteries will not need balancers. The new system with all 4 batteries connected will be 25.6V 120Ah.
12.8V + 12.8V = 25.6V
60Ah + 60Ah = 120Ah