Hey guys, this time we come with the new MAXKGO BMS HV Master Board.

Compared with MAXKGO LV Master Board, HV version has the following two features:

  • 100V to 400V operation
  • Bi-directional current monitoring (up to 2500A pulsed, 500A continuous)

The HV Master Board BMS is developed by MAXKGO in order to adapt new energy vehicle markets. The 400V voltage can meet more needs of electric vehicles, and can provide customers with more better specs choive and bette ruser experience.

In this blog, we will introduce the structure of the HV master-slave BMS, how to match the slave board according to your own needs, and the advantages of the high-voltage board.


The main role of the BMS is to protect the cells inside the battery pack from operating outside of their operating range and to optimize their cycle life by accurately monitoring them (temperature and voltage) while controlling the balancing, charging and discharging process according to the user's requirements Predefined.

For most DIY projects like e-bike or e-scooters that require less than 5 kW of peak power, there are several  BMS on the market that are "good enough" most of the time. When an application requires more than 5 kW of power, those "inexpensive" BMS are becoming insufficient at protecting the pack due to the facts that they do not allow their parameters to be adjusted (Fixed voltage, fixed balancing thresholds, no temperature monitoring & fixed current limits) and are using a solid state switch to disconnect the load from the battery pack in case of an emergency.

Master-slave board BMS is oriented toward high-power applications where the battery pack's long-term performance is critical. Master-slave board BMS is integrated with EVC500 main contactors directly bolted onto the main board and is equipped with a heavy-duty PCB soldered current sensor. The HV Master Board BMS is a high-voltage version of the Master-slave board BMS, with a continuous current of up to 500A and an instantaneous maximum current of 2500A. In order to adapt to the electric vehicle market, MAXKGO developed on the basis of the original version of the Master-slave board BMS The high-voltage version supports a maximum voltage from 100V to 400V.

MAXKGO continues the consistent simple design, which integrating all components on the same board reduces the amount of cabling required and simplifies the installation process.  Master-slave board BMS has a large set of parameters that can be precisely tuned by the user depending on the application. For instance, users can choose to limit the soft discharge and recharge voltages, thus improving cells' durability. Other parameters such as MIN/MAX operating temperatures, balancing threshold value, current limits, and more options can be defined by the user through the app.

The advantages of the HV master-slave board BMS: high channel utilization, flexibility of system configuration, adapting to modules and battery packs of different capacities and specifications.

Slaves boards are offered in three different versions : LTC6811-12S, LTC6812-15S & LTC6813-18S.  All three slave boards share the same built-in functionalities and have the same physical dimensions with similar pins layout. All versions are supported by the master board firmware and uneven cell numbers connected in series is possible. The choice of  which version to use will depend of the pack physical layout and/or the internal modules arrangement.

MKBMS is based on the modular BMS of LTC68XX and STM32 MCU, and is connected to one or more slave boards and integrated integrated boards of different sizes through the ISOSPI interface. The modular BMS can be configured for various applications with battery voltages within 400V.

MKBMS is developed based on the open source materials of DieBieMS and ENNOID BMS. Currently MKBMS is compatible with ENNOID firmware. Here, a special thanks to the developers of open source BMS materials.

  • Technical advantages

1. Hardware advantage

· LTC6820HMS: ADI's LTC6820HMS dedicated digital isolation chip for communication between the master board and the slave board.
· ISO1050DUBR: The CAN port adopts TI's ISO1050DUBR CAN port dedicated isolator.
· STM32F303CCT6: The main control adopts ST's STM32F303CCT6 single-chip microcomputer, which has the characteristics of high performance and low power consumption. It is equipped with a high-speed processor and memory with powerful processing capabilities.
· ISL28022FUZ: ISL28022FUZ of RENESAS is used for current and voltage acquisition, and the ADC is up to 16bit. It supports small signal acquisition and internal amplification to ensure the accuracy of acquisition.

2. Heat dissipation

The MAXKGO master-slave board structure adopts contactor overcurrent, and the master provides detection and control functions. The current passes through the detection resistor and the contactor to form a loop through the wire, thus ensuring the stability of the main board.

Using TE EVC500 contactor, EVC500 is widely used in the current conversion function of electric vehicles, and can provide 900VDC and 500A continuous current carrying.

  • How to choose a suitable slave board

MAXKGO’s HV master board BMS can be used with 24S-95S battery packs. If customers don’t know how to match them (Or there are other requirements: for example, there are requirements for the number of temperature sensors), please contact us through social media or email:, our staff will provide matching schemes and make corresponding wiring diagrams according to your needs.

For the selection and wiring tutorial of the slave board, please refer to the blog "Tips for Slave Board BMS Matching and Wiring"

For the video tutorial of wiring from the board, please refer to:

  •  Installation Tutorial

In addition to the main board, the installation of the split board also requires 2 contactors, a 12V step-down module,power cables and a slave board corresponding to the number of strings.

The contactor is quite an "automatic switch" that uses a small current to control the operation of a large current, (equivalent to an overcurrent judgment switch, when it detects that the current is too large, use this relay to turn off the power output.)
The function of the 12V step-down module is to provide the relay with a 12V working voltage. The operation of the master-slave board BMS requires at least one external 12V power supply to be connected to the 12V connector input. The power supply must be powerful enough to provide the peak power required to close the main contactor and prevent short circuits.

Power cable: BAT+ & LOAD+ must obviously be connected to the main contactor terminals. The BMS needs to be connected as well to those terminals, but only for monitoring battery pack & load voltages. As mentioned earlier, Master-Slave Board BMS Master board is designed around the main contactor and should normally be bolted directly over the main contactors terminals & over the cable lugs.
User can also choose to install the main contactor remotely. In this case, the contactor terminals must be connected to the board with small cables & round terminals connected in their respective mounting holes for enabling the battery pack & load voltage monitoring processes. Keep in mind, the main positive current path does not run through the BMS, but through the main contactor.
On the other hand, the main negative current path must run through BAT- & LOAD- in order to monitor the current going out of the battery pack. The large current shunt resistor is soldered directly underneath the PCB. M8 cable lugs + M8 bolts are required and must be connected directly to the shunt resistor from below.
(Warning: Do not short-circuit the contactor coil outputs. Use contactor with built-in economizer.)

  • Wiring diagram

We will continue to update the wiring tutorial of the HV master board in the future, please don't miss it.

MAXKGO master-slave board BMS can customize different solutions according to customer needs.

You are welcome to contact us via social media or email:, our staff will match the scheme and make the corresponding wiring diagram according to your needs.

We look forward to hearing from you.

Thank you for your patience in reading, see you in the next blog.

Please follow our social media for more info, thanks.




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