When putting batteries in series for a 24V or 48V system it is a good idea to use a balancer. This balancer ensures that the voltages of all the batteries in the pack remain equal and balanced. Without a balancer, especially on lithium systems, the voltage of each of the 12V batteries can drift apart over time. Balancers help to minimise this effect and keep equal voltages across batteries.
The balancers we are talking about here are different to the balancers we use on lithium cells. These balancers balance between 12V batteries, not 3v cells.
