SPecificationS
Cells managed: 4–12 lithium cells per module
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Maximum total voltage: 60VDC
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Compatible chemistries: LiFePO4, LiCo (LiPo), LiMn, etc
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High, low and shunt voltage thresholds: Configurable, 0–5000mV
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Accuracy: Within 0.25% (<10mV)
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Operating temperature range: -40˚C to 85˚C
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Pack balancing: Timed 30Ω shunts (~120mA, up to 1hr)
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Temperature sensing: Dual 100KΩ NTC thermistors (optional)
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Cell quiescent current draw: 1.6mA (idle) 2.2mA (when sampling)
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CAN power supply: 12V nominal (7-16V range), 20mA
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CAN bus specification: 250kbps 29-bit IDs (CAN 2.0B)
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Dimensions: 72 x 66 x 10mm (plus plugs)
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Weight: 35g
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inStaLLation
The module has four 3.2mm (1/8”) mounting holes at the corners as per the diagram below
which can be used to securely mount the module. If fastening above metal surfaces, use
standoffs or an insulating layer in between to ensure that the circuit board does not contact
the metal, which could cause short circuits. Modules should be installed in a location
protected from water and debris – typically, inside sealed battery enclosures is ideal.
BMS12 module dimensions and mounting pattern
It is best to mount the module close to the cells it is monitoring, with flylead lengths of 50cm or
less recommended to minimise induced EMI noise and the chance of wiring/insulation faults.
Be careful not to have one module’s cells spanning mid-pack contactors or emergency stop
buttons, as this can subject the module to damaging high voltages when opened! For similar
reasons, be sure to unplug all BMS modules before doing any battery pack maintenance.
If cells are distributed in multiple groups around the vehicle, we do not recommend setting
the BMS up as a fully centralised system (that is, with HV flyleads from every cell coming to a
group of modules at a single location in the vehicle) because the long HV flyleads are subject
to greater EMI noise and greater chance of potentially dangerous wiring faults.
Once mounted, connect flywires between the 13-pin plug and the cells as per the diagram
below. It is best to leave the plug disconnected from the module while wiring up, and verify
all voltages / cell orders before connecting to the module, in case of wiring mistakes.
If fewer than 12 cells are to be connected, some cell inputs at the positive end will be
unused. The voltage sampling chip powers itself from the most positive screw terminal, so
the most positive cell wire connected must be bridged to the most positive screw terminal on
the BMS module, as shown in the diagram below (right).
ZEVA BMS12 v1.6 (c) 2014
–
+
Shield
Ground
CAN L
CAN H
12VDC
12VDC
CAN H
CAN L
Ground
Shield
Most positive cell
Most negative cell
ZEVA BMS12 v1.6 (c) 2014
–
+
Mos
t pos
itive cell
Mos
t negative cell
typical wiring for BMS module
example wiring with fewer cells
The CAN plugs are Molex C-Grid SL type. They are designed for fairly small gauge wire,
around 22-30AWG. The wire’s insulation needs to be small enough to fit into the plug
housing, which limits outer diameter to about 2mm. The best way to connect wires to pins is
crimping first then adding a little solder to the joint. A suitable crimping tool is available from
vendors such as Altronics (part T1537).
If you don’t have a suitable crimping tool, you can the solder wire directly to the plug,
ensuring minimal gap between the insulation and the back of the pin. You may need to
compress the wings on the pin insert a little for them to fit comfortably into the housing.
When the pin is fully inserted, a barb on the pin should engage a slot in the housing to lock
it in place, and a faint click should be heard. Either inspect visually or give a gentle tug on
the wire after insertion to ensure it is secure. Pins can be removed if necessary by applying
pressure on the pin’s barb with a jeweler’s screwdriver, then the pin can be pulled from the
housing.
Be very careful to avoid short circuits or reverse polarities when attaching flyleads for the
module, as lithium batteries can discharge dangerous current levels and wiring faults can
damage the BMS12 module.
3
2
CAN BUS
ZEVA BMS12 v1.6 (c) 2014
CAN BUS
TEMP1
TEMP2
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+
66mm
72mm
54.6mm
60mm
66mm
