Charger with BMS

The LFP (Lithium) Battery Charger with integrated Battery Monitoring System (BMS) is designed to charge a 12V battery consisting of four LFP cells to about 90% full. (3.5V per cell). The EV battery is made up of 10 x 12V batteries in series (40 x LFP cells.). Ten of these battery chargers are used to charge the ten 12V batteries.

The Battery Charger consists of four main elements:

a. The Transformers and rectifiers.

b. The Charger Controller with Indicators

c. Relays

d. Battery Monitoring circuits

The BMS Charger Block Diagram is shown below:

The next picture shows the circuit diagram for the charger:

The BMS Charger Micro Processor is based on the ATmega328 processor.

The program is written in Basic Language. The listing is given below.

The program was created and compiled with BASCOM AVR and the programmer used is the USB-ISP programmer, both available from

TheBMS Charger layout/construction is shown in the pictures below: