5.2.4. Recommended charging
method
For ambient temperature between
0°C and + 35°C.
&
The charging method described
below is generally applicable for
STM MR-MRE batteries installed
in electric vehicles. However,
individual charging methods
might be required for specific
customer needs, depending on
the application, climatic
conditions, etc. For exceptional
cases, consult Saft.
The recommended charging
method for Saft STM MR-MRE
batteries is two-level constant
current charge IOla, as shown in
the diagram below.
!
Principle
The battery is charged at constant
current. Its voltage increases.
As soon as the predetermined
charging voltage has been
reached, the charge current is
reduced in order to limit useless
heat dissipation during
overcharge while assuring the
necessary overcharge.
The change-point threshold, is
indicated in the diagram by a
small circle.
First level
: constant current at
0.2 C
5
A up to predetermined
threshold voltage.
Second level
: constant current
reduced to 0.05 C
5
A without
voltage limitation.
The charge coefficient is 1.15.
The maximum charging time
of a fully discharged battery is
approximately 8 hours.
!
Temperature compensation
It is essential that the battery
reach the threshold voltage
before it is fully charged. As the
voltage characteristics of Ni-Cd
batteries vary with their
temperature (higher voltage when
cold and lower voltage when
hot), it is imperative to correct the
voltage threshold according to
the battery temperature.
The relation between threshold
voltage and temperature can be
viewed as linear.
The voltage threshold for STM
batteries is indicated at a
temperature of +10°C and is
adjusted according to the battery
temperature with a negative
coefficient in millivolts per °C.
'
Voltage threshold
The voltage threshold that
ends the first level is set at
1.63 V/cell, i.e. 8.15 V
per monoblock.
'
Temperature coefficient
:
For T>10°C
– 0.003 V/°C/cell,
i.e. – 0.015 V/°C/monoblock.
For T<10°C
– 0.006 V/°C/cell,
i.e. – 0.03 V/°C/monoblock.
Cut-off can be manual,
controlled by a time switch,
or electronically.
15
0
0.05
0.2
end of charge
Charge condition (C
5
A)
Second level
Voltage (V)
Voltage (V) Current (A)
Voltage
Set voltage
threshold
Current
Second level
First level
First level
Charge time
Summary of Contents for STM 5-100
Page 1: ...Technical manual installation operation and maintenance for Ni Cd STM MR MRE monoblocks type ...
Page 23: ...Appendix 1 20 Monoblock STM 5 100 MR G RD equipped Positive left Filling right ...
Page 24: ...21 Appendix 2 Monoblock STM 5 100 MRE G RD equipped Positive left Filling right ...
Page 25: ...Appendix 3 22 Monoblock STM 5 140 MR G RD equipped Positive left Filling right ...
Page 26: ...Appendix 4 23 Monoblock STM 5 140 MR D RG equipped Positive right Filling left ...