mBMS Battery Management

Hybrid Technology ComponentsLithium-ion batteries are the preferred energy storage system for modern electrical drive systems. The battery management system mBMS is perfectly adapted to the drives in the powerMELA product family. It permits the safe operation of the battery system and supports battery voltages of up to 800 volts and currents of up to 600 amps.


  • Diesel-electric hybrid drive (HEV)
  • Battery-powered electric travel drive (BEV)
  • Storage power plants

STW’s approach

The mBMS modular system forms the ideal basis for initial prototype constructions and small series. Together with the cell monitoring modules (CSC), it provides all necessary battery management and safety functions. It represents the basic development principle for customer-tailored battery management systems on an industrial scale.

STW offers you all the necessary services so that you can realise your individual high-voltage batteries in state-of-the-art technology and at competitive costs.

Functional safety

The safety concept features multiple stages. A dedicated safety controller only carries out safety functions. The architecture permits safety functions up to SIL2 (EN 61508) and ASIL B (ISO 26262).

Cell voltage monitoring and balancing

Depending on the cell technology, up to 300 lithium-ion cells are connected in series in a battery system. The mBMS supports all standard cell chemistries from the lithium-ion family: LFPNMC and also LTO. Overvoltages and undervoltages in individual cells are indicated as safety-critical statuses in the battery system. Therefore, the mBMS records every cell voltage and warns in good time of pending limit value violations. The CSC modules of the mBMS also supply high-accuracy voltage measuring paths, an overvoltage/undervoltage monitoring system and monitoring of the cell temperatures. On violation of safety limits, enforced switch-off occurs. Passive balancing with 160 mA is provided as the standard for the charge equalisation between the cells. On request, this value can also be adapted.

Current measurement and monitoring

The highly-accurate current measurement is based on the tried and tested ISAscale® technology, with logically-separated limit monitoring. The measurement range is either +/- 300 or +/- 600 amps. Safe switch-off takes place after violation of the current or temperature limits.


Switch-off takes place at both poles through two TE EV200 contacts as a standard feature; alternatives are possible. The ageing and function statuses are automatically diagnosed and recorded.

Pre-charging of the intermediate circuit

Adaptive pre-charging ensures  minimum pre-charging time.

Insulation monitoring

This is already integrated into the mBMSIt is possible to take measurements on the traction network even over the drive inverter.

Determination of status and performance prediction

The state-of charge (SOC) determination takes place by charge balances (Coulomb counting) and automatic re-calibration. The possible performances in charge and discharge operation are estimated through an adaptive algorithm. If required, you can integrate your own algorithms in order to determine the status of the memory. The absence of reaction of customer-specific software on the safety functions is thus guaranteed.

Configuration tools

With the STW Toolchain, you can adapt the mBMS precisely to your battery system:

Cell switching, cell characteristics, temperature characteristics, limits and time characteristics of the safety functions and the interface to the vehicle can be adjusted within wide ranges. The Toolchain and the mBMS together guarantee that the safety characteristics you have specified are actually implemented.

STW initial support

On procuring an mBMS modular system, you receive your first data set (configuration) which is compiled in accordance with your specifications. We are happy to provide you with support during the initial commissioning of your battery system.

Customer-specific BMS developments

As specialists for customer-specific electronics developments, STW provides an inexpensive development and serial production based on the mBMS reference design – the easiest path to your high-quality customer-tailored BMS solution.

Example Applications

Modular Energy Storage System for Hybrid Drive Systems Based on Lithium-Ion Cells 

EVA- Intelligent Electric Taxi for Tropical Megacities

Block Diagram

Battery Management System Hybrid




Electric Power up to 480 kW
Traction Net Voltage up to 800 volts
CAN 4 x CAN 2.0B
System Data
Power supply 8…32 volts DC