WhisperPower
Lithium Plus 12 V 210 Ah 340 Ah
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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 Lithium 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.
4.7.3. CAN bus power
Due to the galvanic separation between the BMS and the Lithium 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 Lithium
battery (figure 17).
1. Connect Pin 1 of Con2 to the + terminal of the Lithium battery.
2. Connect Pin 7 of Con2 to the - terminal of the Lithium battery.
