Depending on the battery cell configuration, the charging current and voltage may vary. Furthermore, based on the chemical and electrical characteristics, the charging configuration can be two- or three-stage. A two-stage charge begins with a constant-current charging phase followed by a constant-voltage charging phase. A three-stage charge profile extends the constant-voltage charging phase by including a float charging voltage to fully charge lead-acid batteries. Table 1 and Figure 1 illustrate these commonly used charge control methods.
Figure 1. Two- and Three-Stage Charging Curves
To perform the charging process, the control system must be implemented either within the charger itself or in an external battery management system (BMS). This can be done by pre-installing the selected charging profile in a smart charger, such as an NPB, so that when the charger detects a battery, it will automatically initiate the charging process according to the pre-programmed profile. Alternatively, the control system can be run through an external BMS using a digital control interface.
On the OLFER Electronics website, you can find this smart charger (NPB series by MEAN WELL). This device, with a power output between 450-1700W, provides a user-friendly, programmable interface, as well as CANBus communication protocol for advanced control via an external BMS. It offers flexible configuration options to meet the requirements of your system or application.
MEAN WELL has filed a patent application for the NPB smart charger, which can charge batteries with various charging requirements. Taking the NPB-450-72 as an example: Its charging range is 54V-100V DC. When set to smart voltage detection mode, it can charge both a Type A battery with a charging voltage of 68V and a Type B or C battery (80V). The only requirement is that the battery incorporates a Battery Management System (BMS).
Intelligent voltage detection determines the battery's internal resistance and transient voltage differences (dv/dt slope) using two separate charging currents. The charger must interrupt charging when the slope of these two parameters becomes positive.
The NPB series provides an intelligent pressure sensing function and can be used to charge batteries for various brands of unicycles, remote-controlled electric vehicles, etc.
