We have been designing and manufacturing protection electronics for Li-Ion batteries for more than ten years.

Rechargeable batteries are a phenomenon of today. The most used are Li-Ion batteries. They can be found practically everywhere - from use in mobile phones, through powering hand tools to large battery energy storage for photovoltaic power plants, or the drive of electric cars.

However, these batteries are very sensitive to the conditions in which they are operated, therefore the use of BMS (Battery Management System) protection electronics is necessary, which safely disconnects the battery if one of the parameters is exceeded. At Tesla, we have been developing protections for 15 years for batteries used in hand tools (drills, saws, grinders, breakers, etc.) Thanks to our own development and the flexibility we can provide, in the future we would also welcome cooperation in other areas of battery use, e.g. small means of transport - electric bicycles, scooters, etc., small work machines, etc.

We can design and manufacture protective electronics (BMS) for charging Li-Ion batteries with the following characteristics:

Protective functions

Overcharge protection

Protection against overheating

Overcurrent protection

Optimizes battery capacity

In order for the battery to be really safely disconnected, our electronics are controlled by a microprocessor, for which we create our own software according to the customer's requirements. Using our BMS protection, the battery is protected several times during operation by monitoring its condition.

Standard monitored statuses include battery overcharging, battery operating temperature monitoring, exceeding the permitted current (for both charging and discharging) and balancing. Safe disconnection of the battery is ensured in the event of a short circuit on the battery terminals, low voltage for operation (i.e. battery discharge below the permissible value of the cell voltage), when the maximum charging current is exceeded.

Thanks to the solution we use, it is possible to very quickly and easily adapt the BMS to the customer's requirements, both parameters and dimensions of the PCB, built-in, etc. Currently, our BMS are designed for 3-16 LiIon cells in series (10.8 to 57.6V) and nominal currents of 50A and more.

BMS can have output communication such as SMBUS, HDQ, UART, RS232, I2C for communication with a superior device, e.g. a charger.

3-16 cells in the series | currents up to 50 A | SMBUS, HDQ, UART, RS232, I2C

We can adapt our BMS to the customer's requirements in the possibility of installation, number of cells and methods of communication.

Why is cell balancing important?

Cell balancing is one of the most important features of BMS electronics. In battery blocks where multiple cells connected in series are used, different cells are charged differently during the operating cycles - charge/discharge. These small differences are caused by the different properties of the individual cells, as no two cells are exactly the same. The result is a gradual divergence of the terminal voltages on the cells. After a certain time, due to these different voltages, the cells are only partially charged and the cells thus use their entire voltage range, which is usually in the range from 3.0 V to 4.2 V for the Li-Ion type. Finally, a situation occurs where part of the cells work in the range of 3.1 - 3.7 V and part of 3.9 - 4.2 V (take as an example). The more cells there are in series, the greater the possibility of gradually unbalancing the accumulator.

Balancing increases the capacity of the battery, when all cells are fully charged and start working again in their entire voltage range. At the same time, which is essential, the lifetime of the entire accumulator is extended.

Passive balancer monitors the voltage on the battery cells during charging. In case of difference between individual cells, the balancer starts to load the cells with the highest voltage (less current flows into more charged cells, more current flows into less charged cells) and thus compares the voltage on the cells. As a result of passive balancing, the cells are charged to the same voltage, but there are higher losses during charging. Passive balancing is not effective - redundant energy turns into heat on the load.

Active balancing is controlled by the processor during charging and discharging. Every cell is monitored - bad ones are discarded. Energy is actively transported between cells from one charged cell to the entire battery or from the entire battery to one less charged cell. Energy transfer will be between adjacent cells or cells in one series branch or in cells between branches. There is a shortening of the battery charge, an extension of its life and an extension of the operating time of the battery pack.

The task of the BMS is to guard, monitor, limit and communicate.

BMS guards

  • voltage
  • current
  • temperature
  • charging
  • discharging
  • battery health

BMS monitors

  • voltage during charging and discharging
  • current during charging and discharging
  • internal impedance of cells
  • stored energy
  • released energy
  • total operating time
  • number of charging cycles

BMS communicates

  • HDQ
  • UART
  • RS232
  • I2C

BMS restricts

  • tips from appliances
  • excessive discharge
  • overheating and hypothermia
  • surge during charging
  • undervoltage during discharge
  • recharge articles