Each battery system requires 1x BMS to be properly wired in, Victron Energy BMS sold separately Why lithium-iron-phosphate - Lithium-iron-phosphate (LiFePO4 or LFP) is the safest of the mainstream li-ion battery types Victron Energy Smart Lithium Battery comes with integrated cell balancing Bluetooth app available to monitor - With Bluetooth cell voltages, temperature and alarm status can be monitored. Very useful to localize a (potential) problem, such as cell imbalance Can be parallel and series connected - Up to 5 batteries can be paralleled and up to four 12V batteries or two 24V batteries can be series connected, so that a 48V battery bank can be assembled Victron Energy Lithium Smart batteries are Lithium Iron Phosphate (LiFePO4) batteries and are available in 12.8 V or 25.6V in various capacities. They can be connected in series, parallel and series/parallel so that a battery bank can be built for system voltages of 12 V, 24 V or 48 V. Each battery system requires 1x BMS to be properly wired in, Victron Energy BMS sold separately.