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this is an important backup, never rely solely on the pack voltage to turn off charge sources and always
ensure the BMS can turn off all charge sources.
Discharge Enable Output (pin 3) - This pin is enabled in both READY and CHARGE modes and is
turned on (pulled low) as soon as the BMS has gone through self checks and
determined that the
battery is able to be discharged. This output will turn off (float high) if the BMS determines that the
battery can no longer provide current or if the maximum discharge amperage is exceeded. This output
can be turned back on again automatically when certain criteria set in the software are met. If the BMS
turns this output off, but still measures current flowing out of the battery pack afterwards, a critical error
will be set on the BMS resulting in the disabling of all charge and discharge until the BMS has been
reset. Please see the software manual for more details on how the BMS determines when this pin is on
or off.
Important:
In addition
to using this output, any connected loads should be set such that they will shut off
in the event the minimum pack voltage is reached as a secondary precaution against over-discharge.
While this is an important backup, never rely solely on pack voltage to stop discharge and always
ensure the BMS can turn off all discharge loads.
Charger Safety Output (pin 5) - This pin is enabled only in CHARGE mode and is used to control
when a charger is turned on. Once the CHARGE power supply is detected by the Orion Jr. BMS, the
BMS will go through self checks and ensure that the battery can accept a charge. Once the BMS
passes all the tests, this output is turned on (pulled low) to enable the charger. Once the battery has
reached its maximum voltage, this output is turned off (float). This output can be turned back on again
during balancing or at set intervals when certain criteria set in the software are met. If the BMS turns
this output off (and if the charge enable output is also off or disabled), but the BMS still measures
current flowing out of the battery pack afterwards, a critical error will be set on the BMS resulting in the
disabling of all charge and discharge until the BMS has been reset. The status of this pin can be
transmitted via the CANBUS. Please see the software manual for more details on how the BMS
determines when this pin is on or off.
Important safety note:
At least two shutoff mechanisms should be present to turn off a charger. The
charger safety signal is designed to be used as a backup if a digital CAN control or digital charge
enable signal fails. If the charger does not support an analog shutoff, an AC relay can be used in series
with the charger power supply. This is the last line of defense if a failure occurs and should not be
omitted.
In addition
to the above safety, the battery charger should be programmed such that it does
not exceed the maximum pack voltage if a failure occurs. While this is an important backup, never rely
solely on the pack voltage to turn off the charger! Always ensure that the BMS is able to turn off all
connected chargers.
Multi Purpose Enable (pin 7) - The function of this pin is assigned in software. This output is an open
drain output. This output will be turned off in the event of a charge or discharge enforcement fault code
no matter what function is selected in software.
Multi Purpose Outputs (pins 9 & 17)
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The function of these outputs can be assigned using the setup
utility. One is commonly used as an output to signal whether an error code is present and can be used
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to drive an error LED, such as the LED on the Orion Jr. BMS basic display board. These outputs are
both open drain outputs which pull down to ground when “ON.” It is important to note that these two
outputs are not watchdog backed and will not turn off in the event of certain faults. These two outputs
should not be used as the sole mechanism to control charge sources or discharge loads.
Important notes about digital signal outputs:
All of these open drain outputs are capable of directly
controlling small relay coils under 175mA and a maximum voltage up to 24V / 30 V maximum for
revision A units and 48V nominal / 60V maximum for revision B and C units. The BMS has internal
protection from the back EMF generated by the relay coils, and additional clamping diodes can be
added for additional protection if desired. Damage can occur to the BMS if currents larger than 175MA
are present, even for short inrush periods. This can lead to undefined behavior of these outputs,
including the shorting of the output. These outputs should not be used to directly drive large contactors.
Some large contactors have a DC:DC converter attached to reduce average power consumption, but
they still require a large inrush current to turn on initially. This large inrush current can damage the BMS
units. These outputs must be amplified if used with large contactors (amplification methods listed
below). The Orion Jr. units have resettable internal fuses on these outputs, but these over-current
protection devices can become damaged from repeated over-current or sustained over-current events.
Always monitor the first charge and discharge cycle manually and ensure that the BMS has
proper control over the loads and the sources of current to and from the battery. If you receive a
charge, discharge, or charger safety relay fault error, immediately investigate to ensure over-
charging or over-discharging is not occurring.
Care must be taken to avoid differences in ground potentials between the BMS unit and other parts of
the application. A difference in ground potentials can cause the digital signal outputs to sink current due
to internal protection diodes (see schematics above). Care must also be taken to ensure that the
voltage on these pins never exceeds 60V. While voltages above 60V are never permitted on these pins,
a voltage exceed 70V will damage the unit and cause these pins to short on “on.”
If additional power is needed or if galvanic isolation is required, the digital signal outputs can be used to
drive opto-isolators or other loads. Below are a sample schematic for connecting a relay with
a coil less
than 175mA and a sample with an opto-isolator. Please note that the below schematics are for general
reference and the suitability of each circuit must be determined by the user.
A sample schematic for connecting the open drain outputs with a relay. Note: For Rev A units, the maximum switching voltage is 24V.