LiFePO4 battery chargers: (1) load Characteristics.admin
For safety and to prolong battery life The Renobat ® Engineering Team describes the safe loading of a lithium battery and makes us see the need for the Chargers to be properly programmed together with the BMS.
Then we will show the process of charging a lithium ferro-phosphate battery. This is a generic load not a specific one; When we have to work with a specific load we will have to take into account the particular characteristics supplied in the “datasheed” of the Manufacturer. Renobat engineers stress that the main concepts that we must take into account is that in lithium batteries the cutting voltages do not have a flexibility as in other Batteries. Most lithium batteries are charged to 4, 2v with a tolerance of ±0, 5mV. Higher voltages would cause stress on the battery which would lead to a reduction in its useful life, although it is more troubling the safety problem that this excess of tension can Entail.
the technicians of Renobat ® will decide the load cycle in very marked stages and determined by the characteristics of the current and voltage Curves. This division will be of great help to explain the process and to better understand the different charging modes of the batteries as some go through all the stages and others do not or do not arrive at the End. In the enclosed table we show a graph in which you can see the different charging phases of the battery.
Some Chargers (link to Carregadors de Li) apply a brief leveling charge to compensate for the small self-discharge of the battery and the consumption of the protection circuit. The charger can start when the Battery’s open circuit voltage drops to 4.05 V and closes again to 4.20 v. The portable device containing the battery must be turned off during charging. This allows the battery to reach the set voltage threshold without locking and to terminate the load with low Current. A parasitic load confuses the charger by pressing the battery voltage and altering the measurement of the current in the saturation phase. The batteries of this type work safely within the fixed limits, but they become unstable if they are overloaded with a voltage higher than the specified ONE. If this threshold is exceeded, lithium plates are started to be formed in the anode, while the cathode produces an oxidizing material, loses stability and produces CO2. The Renobat ® technicians must program a safety mechanism in the BMS so that a thermal leakage cannot be triggered.
to properly acquire, regulate and program the Chargers and BMS of lithium batteries and make a good charge that does not harm the lithium batteries it is essential to have a good technical equipment like the one that Renobat ® (link a Contact) makes available to its Customers.