Victron Energy Lithium Battery Smart batteries are Lithium Iron Phosphate (LiFePO4) batteries and are available in 12.8 V or 25.6 V 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.

The maximum number of batteries in one system is 20, which results in a maximum energy storage of 84 kWh in a 12 V system and up to 102 kWh in a 24 V1) and 48 V1) system.

A single LFP cell has a nominal voltage of 3.2V. A 12.8 V battery consists of 4 cells connected in series and a 25.6 V 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 a 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.

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.