Wiring diagram 123-BMS

The diagram shown on  the right, gives a nice overview of a wired system consisting of a single pack of batteries with BMS-boards, the charger, the current-sensor and in the middle the circuit-board of the 123electric BMS-controller.


For a single pack of say 32 batteries, the system would consist of:

1 BMS-'IN'-board

1 BMS-'OUT'-board

30 ordinary BMS-boards

1 current-sensor (100, 200 or 400 Amp.) and

1 BMS-Controller

 (Important: for sub-divided battery-packs, each sub-pack will have to be equipped with its own BMS-'IN' and BMS-'OUT' -board!)  


The BMS-boards are interconnected with a soldered single-wire, which makes mounting less time-consuming, and very reliable. The 'IN'- and 'OUT'- boards connect via a twisted-pair to the BMS-controller. (or, in case of sub-divided battery-packs, to the next-in-line)

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.

The popular TC-charger is directly controlled from the BMS-controller, without the need for a CAN-interface. The standard three-wire-input connected to the 'charger'-terminal on the BMS-controller is all that is required.

The 'control'-terminal is galvanically isolated, so you can safely connect this to the 12 Volt system of the car.

Two relays (Ry2 and Ry3) serve to warn you when you have forgotten to pull the mains-plug, and when an voltage- or temperature-limit of (one of) the batteries is exceeded.On pin 5 and 8 of this connector, the BMS-controller simulates the signal required by an old-fashioned fuel-gauge.  This way, you can easily indicate remaining capacity (fuel-level) and actual-current. We can supply two meters for this purpose, but if you want to use your existing fuel-gauge, we have made nice calibration-software. (check the 'gauge calibrate'-button in the settings-menu) 

 In the settings-area of the PC-software, one can customise practically anything:

- Voltmeterscale: 10-60V; 40-140V; 100-200V; 150-300V & 250-500V

- Current sensor: 100A ; 200A & 400A

- Cell-capacity: 10 - 999 Ah

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

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

On top of that, one can set the maximum charging-current of the charger, and the minimum current,

One can choose between the Quick- and Balanced-charging-algorithm.

In some countries mains-current is cheap in particular parts of the day. For this reason we have added a real-time clock. If you program an equal start- and stop-time, the timed charging is in-effective.

It is not necessary to enter the number of cells....the system gathers that information by itself, and automatically adjusts the charging-algorithm. 





Download the complete User Manual here (2.0 MB pdf file)