Yes , The battery can be put in parallel or series by customers. But there are few tips we need to pay attention;
① Make sure the voltage of each battery are same before put inparalle. If they are not same, charge them to the same rate
② Don't not put discharged battery and undischarged battery in parallel. This may reduce the capacity of the whole battery pack.
③ Advise us the target capacity of the whole pack if you would like to put them in series. We will choose the suitable BMS for each battery.