Orion Jr. BMS Manual
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Wiring
Voltage Taps
READ THIS ENTIRE SECTION BEFORE WIRING.
Several precautions need to be taken for the BMS
to function properly, accurately, and safely. While the Orion Jr. does not require the use of an in-pack
safety disconnect or fuse, if a safety disconnect or fuse is used, they must be wired in certain
locations. All battery packs must be suitably protected against over-current.
Please see “Safety
Disconnect and Fuse Locations”
for more information.
The Orion Jr. BMS is designed to manage as many as 16 cells, up to a maximum possible voltage of
60V DC, whichever is lower.
For the purpose of this document, a “cell” refers to one or more cells
directly paralleled together. Below is the standard wiring diagram for cell taps. One cell tap is
provided for each cell with one negative tap for each group of 12 cells (in this case 1- and 13-). Cells
are numbered from the lowest stack potential to the highest stack potential (starting at the pack
negative and working up in number towards pack positive.)
The Orion Jr. unit can be used to monitor between 1 and 16 cells in series, with the total pack voltage
not to exceed 60V at any time.
Looking into back of connector (wires coming towards the viewer)
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Wiring - Full 16 Cells
The above image is standard wiring when used with 16 cells.
Rules for fewer than sixteen cells
●
If fewer than twelve cells are populated in group 1 or fewer than four cells in group 2,
unpopulated cells in that group must all be connected to the positive terminal of the highest
potential cell in that group. For example, if only six cells are populated in group 1, taps 6 - 12
are all connected to the positive tap on cell 6.*
●
If no cells in the 2
nd
group (cells 13-16) are used, wires 13-16 (including 13-) should be left
disconnected.
●
In all cases, the Pack+ wire will be connected to the positive most terminal of the positive most
cell.
*In this example, cell tap positions 6-11 could be combined into a single wire that runs to the terminal to
reduce the number of wires entering the battery area.
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Wiring Example - 15 Cells
Wiring example for 15 cells in series. Tap 16 and 15 both attach to positive terminal on cell 15.
Wiring Example - 8 Cells
Wiring example for eight cells in series. Taps 8-12 all attach to the positive terminal on cell 8.
Orion Jr. BMS Manual
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Safety Disconnects and Fuse Position
Sometimes a safety disconnect and/or fuse is located in the middle of the battery pack. This is
sometimes done for safety reasons because opening the disconnect/fuse effectively splits the battery
pack into two smaller packs, making servicing safer by reducing the maximum voltage present and
reducing the potential across the positive-most and negative-most terminals to zero (assuming proper
isolation.) Often times, fuses are integrated into the safety disconnects since they are often used in
conjunction with each other.
The Orion Jr. BMS has internal protection diodes within each cell group that can pass current from one
cell to another if the voltage of the adjacent cell is more than 5V or less than 0V.
If a safety disconnect
or fuse is incorrectly wired to the Orion Jr. such that it is in the middle of a cell group, current
can flow through the Orion Jr. BMS when the fuse blows or when the safety disconnect is
removed, bypassing the safety disconnect or fuse and leading to dangerous conditions.
This
can cause pack voltage to be present at the terminals of the battery pack even though there should be
no voltage present, and large currents can be forced to flow through the Orion Jr. BMS, damaging the
BMS unit. Catastrophic damage to the BMS is possible, and damage from incorrect wiring is not
covered by the warranty.
If a pack safety disconnect or fuses are used, they must be wired in any of three specific
locations - either on the positive-most side of the battery pack, the negative-most side of the
battery pack, or between cell taps 12 and 13- as shown below. In all cases, the BMS cell taps must
be on the battery terminal. It is important that the cell taps be located on the battery side of any pack
fuse or pack safety disconnect. If a fuse is installed on the negative side, it must be located on the load
side of the current sensor. Please see below for more information.