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4.7.1. CAN Bus network topology
The CAN Bus must be used in a bus network topology. Do not use a ring- or a star topology.
The maximum CAN bus legnth is limitted because the Li-ion battery has a fixed bitrate of
250kbps.
In Table 6 is an overview of these restrictions.
Bit rate
Bus length (L)
Max. stub length (S)
Accumulated stub length
250 kbps
250 m
11 m
55 m
Table 6. CAN bus speed
4.7.2. Termination Resistors
The CAN bus requires termination at the two ends of the bus. The USB-to-CAN interface may
be connected in anywhere to the CAN bus.
Use termination resistors at the end nodes to prevent reflections on the line. The value of this
resistor should be +/- 120 ohms.
CAN bus power
Due to the galvanic separation between the BMS and the Li-ion battery’s CAN interface an
external power supply is needed on the CAN bus.
The CAN bus can be powered through Con 2 (I/O Connection 7) (figure 17) or the CAN power
cable. (figure 18)
This situation may occur when a USB-to CAN interface is directly connected to the Li-ion
battery (Figure 17).
1. Connect Pin 1 of Con2 to the + terminal of the Li-ion battery.
2. Connect Pin 7 of Con2 to the - terminal of the Li-ion battery.
