Wiring diagram 123SmartBMS

After the introduction of affordable LiFePO4 batteries, off-grid solutions became feasible. It is vital that such batteries are charged very carefully. In other words, they can easily be over-charged, or over-discharged. Cell-temperature and current are also very important, in order to guarantee a long life.

The 123smartbms Battery Management System (or: BMS) is primarily intended for prismatic LiFePO4-cells, but can also be adapted by the end-user for other cells like Li-Ion and LiPo, provided the cell-voltage is in the range of 2V to 5V.

The diagram shown on  the right, gives a nice overview of a wired system consisting of a single pack of batteries with BMS-boards and the current-sensors.


For a single pack of 4 batteries, the system would consist of:

1 BMS-'IN'-board

1 BMS-'OUT'-board

2 Ordinary BMS-boards

2 Current sensor


To measure current during charging and dis-charging, the current sensor should be connected in the position indicated. This is important, as this sensor is used for the so-called Coulomb-counting software, with which the BMS-controller calculates the remaining battery-capacity.


 In the settings-area of the Bluetooth App, one can customise practically anything:

- Battery-capacity: 0.1 - 999 kWh.

- Cell-voltages (Vmax, Vmin, Vbypass & V-recharge)

- Cell-temperature (Tmax, Tmin in degrees Celsius)







Download the complete 123SmartBMS gen3 manual here (1.7 MB pdf file)


123SmartBMS App

 Get it on Google Play 




Extended Module

Download the 123SmartBMS Extended Module software installer here