Hardware Manual
BMS Master 4 / 4.5
Ref.: IR14417 A 15.01.2018 Page 46/76
3.5.4.4 SENSOR- AND PTC-INTERFACE
According to the slave software an NTC-resistor with a cold resistance of 10 k at 25 °C
has to be used as temperature sensor.
To supervise the cells on over temperature a PTC-resistor may be mounted on each cell
surface. All PTCs will have to be connected in series. The cold resistance of the chain must
be smaller than or equal 10 k. A suitable PTC e.g. is EPCOS B59701C0070 in size 0805
to detect temperatures above 70°C. A chain of 10 of those PTCs would have a resistance
of less than 5 k at 25°C.
If only one PTC in the chain becomes high resistant because of over temperature (the
total chain resistance must exceed 22 kΩ), the FAILn-output will be activated and
signalled to the master module. The PTC-over temperature interface is active while there
is data traffic on the RS485-interface and 2 seconds further on. This time delay cannot be
altered by parameters.
When this supervision interface shall not be used, the PTC chain must be replaced by a
single resistor of 100 to 1k. The temperature and over-temperature interface is part of
the 24-pole connector. Pin assignment see above: pins 6 and 7 for the PTC’s and pins 8
and 9 rsp. 20 and 21 for the NTC’s.
ATTENTION: Because the slave module is supplied out of the battery cells,
the temp sensors are connected with a cell voltage as well. The voltage
difference between slave modules and sensors may exceed some hundreds
of volt depending on total battery size!
A sufficient insulation of sensors and cables is mandatory!
3.5.4.5 BALANCING RESISTORS
Depending on the cell voltage, there are various slave 5 A module. The types are shown in
the following table:
Voltage range
balance current
cell type
U [mV]: 1500 … 2800
I [mA]: 73 … 137
Cell type: LTO cell
U [mV]: 2800 … 4200
I [mA]: 62 … 93
Cell type: NCA cell
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