Lithium battery 20Ah 12.8V SuperPack - Victron Energy

Why lithium iron phosphate batteries?

Lithium iron phosphate batteries (LiFePO4 or LFP) are the safest among traditional lithium-ion batteries. The nominal voltage of an LFP cell is 3.2 V (leaded: 2 V / cell). A 12.8 V LFP battery is made up of 4 cells connected in series, and a 25.6 V battery is made up of 8 cells connected in series.

Robust

A lead-acid battery will fail prematurely due to sulfation:

• If it operates in deficit mode for long periods (ie the battery is rarely or never fully charged).

• If it is left partially charged, or worse, fully discharged (for yachts or mobile homes during the winter).

It is not necessary to fully charge an LFP battery. The service life even improves slightly with partial charge instead of full charge. This represents a major advantage of the LFP battery over the lead acid battery. These batteries have other advantages such as a wide operating temperature range, excellent cycle performance, low internal resistance and high efficiency (see below). An LFP battery is therefore the chemistry of choice for very demanding applications.

Efficient

For several applications (in particular autonomous solar and / or wind applications), energy efficiency can be of crucial importance. The return energy efficiency (discharge from 100% to 0% and return to 100% charged) of an average lead battery is 80%. The round trip energy efficiency of an LFP battery is 92%. The charging process for lead-acid batteries becomes particularly inefficient when the state of charge has reached 80%, giving efficiencies of 50% or even less in the case of solar systems when several days of reserve energy is required (battery working with a state of charge of 70% to 100%). On the other hand, an LFP battery will reach 90% efficiency under light discharge conditions.

Height and weight

• 70% space saving.

• 70% weight gain.

High price ?

LFP batteries are very expensive compared to lead batteries. But for demanding applications, the initial high cost will be more than offset by an extended service life, superior reliability and excellent efficiency.

Bluetooth

The status of cell temperature and voltage alarms can be monitored by Bluetooth. Very useful function to locate a (possible) problem, such as an imbalance on the cells for example

Our LFP batteries are equipped with balancing and cell monitoring functions. Up to 5 batteries can be installed in parallel and up to 4 batteries can be connected in series: thus a 48 V battery bank of up to 1500 Ah can be assembled. Balancing / cell monitoring cables can be connected in series, and they must be connected to a Battery Management System (BMS).

Battery management system (BMS)

The BMS is connected to the BTV and its main functions are as follows: 1. Disconnect or switch off the charge each time the voltage of a battery cell drops below 2.5 V. 2. Stop the charging process each time that the voltage of a battery cell exceeds 4.2 V. 3. Switch off the system each time the temperature of a cell exceeds 50 ºC. See the BMS data sheets for more functions.