Zeva BMS12i User manual

ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
ZERO EMISSION VEHICLES AUSTRALIA
http://www.zeva.com.au
BMS12i
4-12 Cell Lithium Battery Management System
Introduction
The ZEVA BMS12i is an integrated battery management system for lithium battery packs
containing 4-12 cells in series and 5-1200Ah capacity. It is suitable for both electric vehicle
and battery storage applications. The BMS12i includes an internal power supply to allow it to
run directly from the battery pack, internal shunt resistors for automatic pack balancing, dual
solid state relay outputs for switching power contactors to protect charging and discharging
of batteries, built-in current shunt interface for measuring current and calculating battery
state of charge, and a CAN bus port for optional colour touchscreen interface or integration
with third party control systems.
The BMS12i Monitor provides information such as voltage, current, power, battery state of
charge, and all individual cell voltages. It can also be used for conguring the operating
parameters of the BMS12i. It may be installed up to 50m from the BMS (if correct shielded
twisted pair cable is used).
Battery management systems are the last line of defence for your battery pack. In normal
circumstances it should not interfere with the battery pack’s operation, only intervening
when something goes wrong and protection is required.
Safety Warning
Although 4-12 cell lithium battery packs do not involve lethal voltages, they frequently
involve dangerous amounts of current and power. Proper precautions and electrical
safety procedures should always be observed. Please read this manual carefully to ensure
correct installation and operation. If you are unsure of anything, please contact us before
proceeding.
We have endeavoured to make a safe and reliable product which performs as described,
however since ZEVA has no control over the integration of its products into a battery system,
we can assume no responsibility for the nal safety or functionality of the completed
installation. It is up to the end user to determine the suitability of the products for the purpose
employed, and the end user assumes all risks associated. Products should only be installed
by suitably qualied and experienced persons, should be tested thoroughly after installation
to verify correct operation, and should always be used in a safe and lawful manner.
Specications
Number of cells: 4-12•
Battery types: LiFePO4, LiCo, LiMn, NMC, etc•
Accuracy: Within 0.002V per cell•
Battery capacity: 5-1200Ah•
Current measurement: Up to 1000A via shunt interface, or 1200A via CAN hall sensor•
Dimensions: 104x78x18mm, 2x Ø4mm mounting holes 98mm apart•
Outputs: Dual solid state relays, 60V 1A max, internally fused•
CAN bus interface (non-isolated), 250kbps 29-bit by default•
Power consumption: Approx 30mA when running (with both output relays closed and a •
monitor connected to the CAN bus), 8mA when sleeping.
Installation
The BMS12i should be mounted securely using screws through the holes on the case anges.
Install the BMS12i in a location protected from direct sun and water, and close to the cells if
possible to minimise cell wiring lengths (under 1m recommended).
The BMS12i has a pluggable screw terminal block for the cell connections, with the most
negative point of the battery pack connected to terminal B–, and successive positive
terminals connected to 01–12. Wire gauge around AWG20-22 is recommended for sufcient
mechanical strength and suitable current rating. To t wires, strip about 8mm of insulation off
the end, turn the screw terminal counter-clockwise about 8 turns to lower the clamping bar,
insert the wire into the hole, then turn clockwise until the wire is held rmly. We recommend
wiring up the plug and verifying all voltages before connecting to the BMS. The plug requires
a signicant amount of force to fully engage; ensure it is plugged all the way in for reliable
connections.
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ZEVA BMS12i
www.zeva.com.au
HV Relay
Power
LV Relay
CAN L
Ground
6V Out
CAN H
Temp
Ground
Sleep
Shunt
B+ 11 10 09 08 07 06 05 04 03 02 01 B–

ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
If you need to disconnect the cell plug from the BMS, signicant force is required for removal
as well. For easier removal, a at blade screwdriver may be used to lever the positive end of
the plug out rst, which should then be loose enough to remove by hand.
Ensure that all wiring is secured so it will not become damaged from vibration or abrasion.
Small fuses (~1A) may be used to protect wiring, best installed close to each cell terminal.
Device power is always taken from terminal B+. To provide power to the BMS, simply add
a short jumper wire from your most positive cell terminal to B+. (You can optionally run a
dedicated wire from battery positive to B+ to avoid voltage measurement errors on your most
positive cell, though it is usually only a few millivolts.) An example wiring diagram for 10
cells is shown below.
Relay outputs are oating / isolated, and have a maximum rating of 60V and 1A continuous.
In installations with a single “battery enable” relay, the LV and HV relays may be wired in
series such that either an over-voltage or under-voltage condition will open the relay to
isolate the battery pack as shown on the following page.
Once your wiring is complete, press the power button on the top left of the case, and the
status LED should come on. A green light indicates all cells are within correct voltage range,
and both relay outputs will be closed circuit. A steady red light indicates one or more cells
are over-voltage, and the HV Relay outputs will be open circuit. A blinking red light indicates
one or more cells are under-voltage, and the LV Relay outputs will be open circuit. Green/
red ashing indicates an over-temperature shutdown.
Protection Using a Single Contactor
It is possible for the BMS to control a single contactor
to protect against both under-voltage and over-voltage
conditions concurrently. To achieve this, the HV Relay and
LV Relay terminal pairs should be wired in series, as per
the diagram, right.
Note that in this conguration, if the BMS opens the
main contactor due to an under-voltage cell for example,
the battery pack will also be isolated from any charging
sources so will be unable to charge (and correct the under-
voltage condition) until the system is reset manually. For
this reason it is important in this case that BMS intervention is an exceptional circumstance,
and under normal operation chargers and loads will not cause any cells to exceed safe
range.
Current Shunt
The BMS12i may be supplied with either a 100A, 200A or 500A shunt. The shunt may
be installed at either the negative end, positive end, or even somewhere in the middle of
the battery pack. The shunt is connected via two wires to the associated terminals on the
BMS12i. For best performance, twisted pair wire is recommended. The sample wire from
the anode / positive side of the shunt (closest to the +ve terminal of the battery) should
be connected to the left-hand terminal (as shown on the wiring diagram, left). By default,
discharge amps are shown positive, though this can be reversed in settings if preferred. If
your polarity seems to be reversed (e.g discharge current is causing SoC to increase), simply
swap the two shunt wires at the BMS.
The BMS stores calibration for the shunt zero point in memory. If the current displayed is not
zero when it should be, you can hold a nger on the monitor to bring up Options buttons,
then tap Zero Current (while no current is owing) to recalibrate the zero point.
Temperature Sensing
A temperature sensor may be connected to the BMS12i between the Temp and Ground
inputs. The scaling is calibrated for a 100Kohm NTC thermistor with B25/100 value of
4540K. These are available from us, or many large electronics vendors.
It is recommended that the temperature sensor is installed somewhere near the middle of the
pack, since this is typically the warmest location. Wires on the sensor may be extended as
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ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
long as necessary. Temperature limits may be adjusted in settings, to warn if the temperature
exceeds safe range, restrict charging if the battery is too cold, or shut everything down if the
battery gets too hot.
Sleep Mode
The BMS12i has a Sleep terminal which may be used to put the device into a lower power
standby mode by connecting a wire from it to a Ground terminal. It is most commonly
used in mobile applications, for when a vehicle is neither being driven or being charged.
(Stationary applications typically run 24/7 so the Sleep terminal is often unused.)
Sleep mode will shut down the CAN bus and turn off both relay outputs. The device continues
to monitor cell voltages and shunt current, and will turn itself off completely if any cells get
extremely low.
Automatic Pack balancing
In battery packs built from many cells, optimum performance is attained when all cells are at
the same State of Charge, also known as pack balance. The BMS12i uses a system known as
“shunt balancing”, which switches on resistors across any cells which are above a threshold
voltage to reduce their charge and bring them into line with other cells.
By default the BMS12i uses a dynamic balance threshold, where any cells more than 0.01V
above the average receive balancing. The threshold may also be set manually – if so it is
best to set it to the average maximum charge voltage, so that only cells above average at the
end of a charge receive balancing. Manually setting a shunt threshold below the maximum
charge voltage is not recommended since it may result in all balancers running concurrently,
which actually negates the effect and generates extra heat. Balancing can also be disabled.
The shunt balancers are quite small and can take a long time to correct large imbalances. If
possible it is recommended to manually balance your cells prior to initial pack assembly (e.g
by charging each cell individually, or wiring them all together in parallel to equalise with each
other). However the shunts will get an unbalanced pack incrementally closer to balanced each
charge, and once balanced are able to maintain balance with minimal effort.
CAN Bus Wiring
The BMS12i has four screw terminals for connecting CAN bus
wiring: 6V Out, CAN H, CAN L and Ground. The monitor CAN
plug uses a Molex Eurostyle screw terminal. These connectors
require some force to plug in, so make sure the plug is fully
inserted for a reliable connection. Wiring for the Eurostyle
connector is shown right.
Wire gauge around 20-24AWG is recommended for appropriate current rating and
mechanical strength. For best noise immunity in high EMI environments, shielded twisted
pair cable is recommended, with two conductor pairs – one pair for CAN signals, and one pair
for bus power. The shield can be connected to the Ground terminal at the BMS. We use and
recommend Belden 8723 wire or equivalent.
For optimum performance, CAN buses should be wired as a single daisy chain of devices
(without branching), and terminated at both ends of the bus with a 120Ω resistor across the
CAN H and CAN L lines. The monitor includes termination resistor built-in. Note that the
CAN bus shares its ground reference with battery negative (it is not an isolated interface).
The 6V Out terminal is limited to 200mA current and is primarily intended for powering CAN
devices such as a monitor and/or CAN current sensor, but may also be used to power other
small 6V devices such as solid state relays.
BMS12i Monitor
The BMS12i Monitor is an optional colour touchscreen which may be used to remotely
interact with the BMS12i. The Monitor displays various pages of information:
BMS Status: Running
Voltage
Current
Power
Temp SoC
23˚C 90%
48.5V
12.3A
0.6kW
The BMS Status page is the standard display when
the system is running, showing pack voltage, current,
power, temperature, battery state of charge. This will
only be shown if a current sensor is present.
Tapping the panel on the left or right side will toggle
between the different display pages.
BMS Summary: 12 cells
Avg Volts Temperature
Min Volts Max Volts
3.32V 25˚C
3.31V 3.33V
The BMS Summary page shows the average, minimum
and maximum cell voltages, and the temperature
sensor, plus a bar graph overview of all cells across
the bottom.
If no current sensor is present, this will be the default
page, and Pack Voltage will be shown instead of
Average Voltage.
BMS Details: 12 cells
3.324 3.332 3.327 3.315
3.331 3.313 3.325 3.322
3.318 3.326 3.339 3.322
The BMS Details page shows all individual cell
voltages, plus a bar graph below. Dotted lines on the
graph show HV and LV thresholds plus hysteresis.
Graph bars will be green when a cell is in range, blue
for under-voltage, red for over-voltage, and orange if a
cell is currently being shunt balanced.
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Shield
Ground
CAN L
CAN H
6VDC

ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
Warning:
Overcurrent shutdown
If the BMS detects an error, this warning page
will be displayed. In most cases, the error can be
acknowledged/reset by tapping the screen.
Enter Setup
Reset SoC
Zero Current
Power Off
Exit Options
You can bring up the options menu by touching and
holding for 1 second. From here you can do a manual
reset of the State of Charge (back to 100%), enter the
Setup mode, switch the display off, or command the
BMS12i to turn off.
ZEVA BMS: Setup
Parameter:
Pack capacity
Value:
100Ah
Exit Setup
<
<
>
>
If you choose Enter Setup, the Monitor can be used to
modify settings for the BMS12i. The top row selects the
parameter, and the bottom row adjusts the value, in
both cases by touching the left or right arrows on each
side. Once nished, touch Exit Setup and the new
parameters will be transmitted to the BMS12i.
List of Settings
The following table describes the parameters available in the Settings page.
Name Range Description
Pack capacity 5-1200Ah The rated capacity of your traction battery pack,
in Amp-Hours.
SoC warning 0-100% The BMS12i can raise a warning when the
battery’s State of Charge reaches a predetermined
minimum level. (Use 0% to disable.)
Full voltage 1-70V The BMS uses a “full voltage” threshold
(combined with low charge current) to detect
charge completion and automatically re-
synchronize the SoC to 100% when pack
voltage exceeds this value. Typically set value to
just below your peak charge voltage.
Warn current 0-1200A The BMS12i will provide a warning if the current
in or out of the battery exceeds this threshold.
Set to 1210A to disable (will display as “off”).
Trip current 0-1200A The BMS12i will automatically shut down the
battery pack if current exceeds this threshold
(for over 1 second continuously). Note: This
should not replace a physical fuse, but can be
used as a “rst line of defence”.
This is considered a serious error which will
require the device to be power cycled to reset.
Num cells 4-12 The number of cells the BMS should expect to
see in the battery pack. Warning: If this is set
incorrectly, some cells may not be monitored.
Shunt size None, 100,
200 or 500A
Selects the size of current shunt connected to
the BMS’s shunt interface terminals, for correct
current scaling. (75mV shunts only.)
This should be set to “None” if you have no
shunt connected, or are using an external
current sensor on the CAN bus.
Min voltage 1.50-4.00V The minimum voltage any single cell should
be allowed to reach. If any cell goes below
this threshold, the LV output relay will go open
circuit.
Max voltage 2.00-4.50V The maximum voltage any single cell should
be allowed to reach. If any cell goes above this
threshold, the HV output relay will go open
circuit.
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ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
Balance voltage 2.00-4.50V,
Dynamic
or Off
The voltage threshold where shunt balancing will
occur. Balancing should only be performed on
cells which are higher than average, so typically
set this to the average maximum charge voltage
of each cell (i.e max charge voltage divided by
number of cells).
Set to 4.51V for dynamic balance voltage or
4.52V for Off.
BMS hysteresis 0.00-0.50V Applies to Stationary Mode only. Adds hysteresis
to min/max voltage reset thresholds, so that
charge and load relays are not switched on and
off too rapidly. For example, after an under-
voltage trip, the LV relay won’t be re-enabled
until the cell recovers to 0.2V above Min
Voltage.
BMS min temp -41C to 100C The minimum allowable temperature for
the battery pack. If a temperature below
this threshold is detected, a warning will be
generated and charging will be disabled.
Set to -41C to disable (will show as “Off”)
BMS max temp 0-101C The maximum allowable temperature for
the battery pack. If a temperature above
this threshold is detected, a warning will be
generated and chargers and loads will both be
disabled.
Set to 101C to disable (will show as “Off”)
Charger voltage 0-70V Applies to CAN bus integration withTC Chargers
or SMA/Goodwe inverters only.
The maximum voltage that the BMS will instruct
the charger/inverter to reach.
Charger current 0-100A Applies to CAN bus integration withTC Chargers
or SMA/Goodwe inverters only.
The maximum current that the BMS will instruct
the charger/inverter to reach.
Stationary mode No/Yes Whether the BMS behaviour should be set for
stationary applications. Please see “Stationary
Mode” section for further explanation.
Reverse current display No/Yes By default, the BMS12i displays discharge amps
as positive / charge amps negative. If preferred,
you can reverse the display so that discharge
amps are negative / charge amps are positive.
Night Brightness 0-100% Adjusts the brightness of the LCD display in
low light mode, to reduce screen glare at
night. Toggle between full brightness and night
brightness by swiping a nger up/down.
Buzzer On Yes/No Selects whether the Monitor should sound the
buzzer for alerts. (Safest to leave this on.)
Use Fahrenheit Yes/No Changes display of temperature units to
Fahrenheit instead of Celcius.
SoC Display Percent or
Amp-Hours
The battery State of Charge value displayed on
the Monitor can either be shown as a percentage
of full charge, or as the number of amp-hours
remaining.
Stationary Mode
The BMS12i has two main modes of operation, either normal (for mobile / EV applications)
or Stationary Mode (for off grid / backup battery type applications). In normal mode, if an
under- or over-voltage is detected, the LV or HV output relay will be disabled respectively,
and will remain off until the device is either power cycled or (more commonly) they are re-
enabled whenever the device wakes from sleep.
In Stationary mode, the outputs will automatically reset if the voltage recovers sufciently.
The BMS Hysteresis setting is used to adjust the amount that the voltage needs to recover
before outputs are re-enabled. For example, if the HV output has been disabled due to an
over-voltage cell, a Hysteresis setting of 0.2V will prevent the output from re-enabling until
the high cell has fallen more than 0.2V below the Max Voltage setting.
Common settings for LiFePO4 cells are a Min Voltage setting of 2.50V, Max Voltage of 3.65V,
and Hysteresis of 0.20V, giving a 2.5V-2.7V band for the LV Relay output and 3.45V-3.65V
band for the HV Relay output. LiCo cells have a more linear charge curve so typically need a
smaller hysteresis band around 0.10V, with a Min Voltage setting of 3.00V and a Max Voltage
setting of 4.2V.
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ZERO EMISSION VEHICLES AUSTRALIA 4-12 CELL LITHIUM BATTERY MANAGEMENT SYSTEM
LED Status Codes
The BMS has a bicolour (red/green) LED
which it uses to display its operating
status. The table to the right summarises
the colour codes for the possible statuses
indicated.
Status Colour
Running (no errors) Green
Sleeping Blinking green
Under-voltage trip Flashing red
Over-voltage trip Steady red
Thermal trip Flashing red/green
BMS Power Consumption Protection
An inherent problem with any BMS which powers itself from the cells it is monitoring is that
the BMS itself can slowly discharge the cells, which can eventually atten cells – particularly
if powering contactors or monitors, and if no charging source is present for an extended
period. To prevent possible damage, the BMS12i is able to switch off its own power supply
if any cells get critically low (under 2.0V). If your BMS has turned off due to a critically low
cell, simply attach a charging source to the batteries then press the power button to re-enable
the BMS.
If the battery system is not in use for a while (days to weeks) it is recommended to put the
BMS to sleep by joining the Sleep terminal to Ground, to reduce power consumption. If the
system will not be used for a long time (weeks or longer) it is recommended to turn the BMS
off, by bringing up Options buttons then tapping Power Off (or unplug the cell connector, if
you have no Monitor).
Tech Support and Warranty Information
All ZEVA products are covered by a 12 month warranty against manufacturing faults or
failures under normal operating conditions. The warranty does not cover misuse of the
product, including but not limited to: excessive voltage or reversed polarity on terminals,
short circuits on outputs, opening of housings and/or modication of internal electronics,
severe impact damage, submersion in water.
We have taken great care to design a safe and reliable product, but faults can happen. If
you believe your product has a fault, please contact us via our website to discuss. If it is
determined that a hardware fault is the likely cause, we will provide an RMA number and
return address to proceed with repairs.
If you have any questions not covered by this manual, please contact us via our website:
http://www.zeva.com.au
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