REC ACTIVE BMS 4S
12
www.rec-bms.com
Digital Outputs:
Digital outputs are implemented with galvanical isolation. Darlington optocouplers with diode reverse protection
are used. When closed, 0.9 V voltage drop over the digital output should be taken into account. Optocoupler
outputs can drive small signal relays or LED diodes. Fig. 7 shows two different connection schematics. Both outputs
can be used to drive LED diodes for charge/discharge relay indication. Both digital outputs can be modified as non-
galvanically isolated outputs with PWM or even digital inputs.
Figure 7:
BMS digital outputs schematics.
Current limit resistor R can be calculated as:
𝑅 =
𝑉
CC2
− 0.9 𝑉 − 𝑉
FVLED
𝐼
LED
V
FVLED
represents LED forward voltage drop (typ. 1.9 – 2.3 V) while
I
LED
represents LED current (2-5 mA).
