When we selecting batteries for RC model equipment, Li-Po batteries are generally preferred because they have the advantages of high energy density, low self-discharge rate, no memory effect, and long cycle life compared to other types of batteries.
However, the most fatal weakness of lithium batteries is that they cannot be overcharged and over-discharged.
From the molecular point of view, it can be intuitively understood. Overcharging will force too many lithium ions into the carbon structure of the negative electrode, and some of them can no longer be released.
The excessive discharge will lead the copper plating of the negative plate to the positive electrode and destroy the microstructure of the positive electrode. The excessive discharge will lead to the excessive release of lithium ions from the negative carbon and lead to the collapse of its slice layer structure.
Whether it is overcharge or over-discharge, it has an irreversible impact on the capacity and life of the lithium battery, and sometimes even has a greater impact on its safety.
And common RC Li-Po batteries, for safety, it is recommended to use a balanced charger to charge, such as Enegitech E430 balance charger.
The principle of the balance charge is briefly discussed below.
As shown in the figure above, in general, when charging 2S and above batteries in non-balanced charging mode, each cell is in series.
Due to the internal resistance between the cells there are some differences, according to the series voltage principle, the actual distribution of the voltage will be slightly different.
Because the charger monitors the total voltage, some battery cells may be overcharged when the total voltage has not reached the cut-off voltage.
Instead, if use the balanced charging mode in the figure above, the charger monitors the voltage of each cell.
Which one of the cells reaches the cutoff voltage first will be disconnected first, and the other cells will not be affected.