12,8 & 25,6 Volt Lithium-Iron-Phosphate Batteries Smart
With Bluetooth
Victron Energy Lithium Battery Smart batteries are Lithium Iron Phosphate (LiFePO4) batteries and are available in 12.8V 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 12V, 24V or 48V.
The maximum number of batteries in one system is 20, which results in a maximum energy storage of 84kWh in a 12V system and up to 102kWh in a 24V* and 48V* system.
A single LFP cell has a nominal voltage of 3.2V. A 12.8V battery consists of 4 cells connected in series and a 25.6V battery consists of 8 cells connected in series.
Why lithium-iron-phosphate?
Rugged
A lead-acid battery will fail prematurely due to sulfation:
• If it operates in deficit mode during long periods of time (i.e. if the battery is rarely, or never at all, fully charged).
• If it is left partially charged or worse, fully discharged (yacht or mobile home during wintertime).
A LFP battery:
• Does not need to be fully charged. Service life even slightly improves in case of partial charge instead of a full charge. This is a major advantage of LFP compared to lead-acid.
• Other advantages are the wide operating temperature range, excellent cycling performance, low internal resistance and high efficiency (see below).
LFP is therefore the chemistry of choice for demanding applications.
Efficient
• In several applications (especially off-grid solar and/or wind), energy efficiency can be of crucial importance.
• The round-trip energy efficiency (discharge from 100 % to 0 % and back to 100 % charged) of the average lead-acid battery is 80 %.
• The round-trip energy efficiency of a LFP battery is 92 %.
• The charge process of lead-acid batteries becomes particularly inefficient when the 80 % state of charge has been reached, resulting in efficiencies of 50 % or even less in solar systems where several days of reserve energy is required (battery operating in 70 % to 100 % charged state).
• In contrast, a LFP battery will still achieve 90 % efficiency under shallow discharge conditions.
Size and weight
• Saves up to 70 % in space
• Saves up to 70 % in weight
Expensive?
• LFP batteries are expensive when compared to lead-acid. But in demanding applications, the high initial cost will be more than compensated by longer service life, superior reliability and excellent efficiency.
Bluetooth
• With Bluetooth cell voltages, temperature and alarm status can be monitored.
• Instant readout: The VictronConnect App can display the most important data on the Device list page without the need to connect to the product.
• Very useful to localize a (potential) problem, such as cell imbalance.
Six tailored BMS solutions
• There are 6 different BMS models tailored for various applications available for use with the Lithium Battery Smart. The system design and BMS selection guide in the battery manual provides an overview and explains the differences between them and their typical use.
*To reduce required balancing time, we recommend using a little different batteries in series as possible for the application. 24 V systems are best built using 24 V batteries. And 48 V systems are best built using two 24 V batteries in series. While the alternative, four 12 V batteries in series, will work, it will require more periodic balancing time.
Our LFP batteries have integrated cell balancing and cell monitoring. The cell balancing/monitoring cables can be daisy-chained and must be connected to a Battery Management System (BMS).
Battery Management System (BMS)
The BMS will:
1. Generate a pre-alarm whenever the voltage of a battery cell decreases to less than 3.1 V (adjustable 2.85 V – 3.15 V).
2. Disconnect or shut down the load whenever the voltage of a battery cell decreases to less than 2.8 V (adjustable 2.6 V – 2.8 V).
3. Stop the charging process whenever the voltage of a battery cell increases to more than 3.75 V or when the temperature becomes too high or too low.