REC ACTIVE BMS 4S
9
www.rec-bms.com
CAN Communication Protocol (installed and programmed on request):
Figure 5:
CAN
female DB9 connector front view.
Table 4:
CAN
DB9 connector pin designator.
pin
designator
1
TERMINATION
2
CANL + TERMINATION
3
GND
4
5
-
6
+ 5V
7
CANH
8
-
9
BMS Unit Start Procedure:
When the BMS unit is turned ON it jumps into a boot-loader and checks if the user tries to upload a new firmware.
Then it commences the test procedure by checking the balancing fuses and temperature sensors. After the test
procedure red error LED turns off and the BMS unit starts working in normal mode.
BMS Unit LED Indication:
Power LED (green) is turned on in 1 s intervals, if the BMS is powered. Error LED (red) is turned on in case of system
error and blinks number of error with 50% duty cycle. Between every number blinking, a small timeout is
introduced.
Cell Voltage Measurement:
Cell voltages are measured every second. The cell measurement algorithm performs several measurements to
digitally filter the influence of 50, 60, 100 and 120 Hz sinus signal. Each cell voltage is measured after the balancing
fuse, in case the fuse blows, BMS signals error 10 to notify the user.
BMS Cell Balancing:
Cells are balanced actively with very high efficiency in opposite to passive balancing, where all energy is lost in heat.
Another benefit of active balancing is charging of dangerously low cell, if other cells are above dangerous level,
consequently longer pack usage is possible.
