Lithionics Battery NeverDIE User manual

MiniBMS
OptoLoop
UL Ratings
UL 508 - Contactor
UL 991 - BMS
UL 1998 - BMS
UL 1973 - System
TECHNOLOG
NeverDie
®
Advanced BMS
–
User Guide
R8.0. – 10/2 /2018
®
TECHNOLOG
®
®

Notice of Copyright
NeverDie® BMS Product Manual Copyright © 2018 all rights reserved. No part of this document may be reproduced in any form
without the express consent of Lithionics Battery, Clearwater, FL 33765 USA. Lithionics Battery reserves the right to revise this
document and make periodic changes to the contents without obligation or organization of such changes and revisions.
Safety Precautions
All electrical work should be performed in accordance with local and national electrical codes.
Voltage is present at the battery terminals, use insulated tools and gloves while working on the system.
Always turn off equipment connected to the system in addition to turning OFF the Power switch provided on the system to
isolate the batteries from other electrical circuits, before performing any repairs or maintenance on the system.
Always use proper wire sizes to connect the system to inverters, chargers or other equipment.
Always use crimped connections to connect to the battery terminals.
Read and follow the inverter, charger or other equipment manufacturers safety precautions prior to connecting the system
to that equipment.
Index
Table of Contents
Index ................................................................................................................................................................................................2
Overview ..........................................................................................................................................................................................3
Installation ......................................................................................................................................................................................3
Definitions .......................................................................................................................................................................................3
BMS Operation ................................................................................................................................................................................5
SOC Gauge operation ....................................................................................................................................................................6
System Status bits .........................................................................................................................................................................6
Bluetooth Telemetry ......................................................................................................................................................................8
ED Indicators ................................................................................................................................................................................8
BMS Troubleshooting .....................................................................................................................................................................8
Advanced BMS functions ...............................................................................................................................................................9
BMS Configuration....................................................................................................................................................................... 11
Serial Data Interface ................................................................................................................................................................... 12
TCP/IP Data Interface ................................................................................................................................................................ 13
CANBus Data Interface ............................................................................................................................................................... 14
AMPSEA Connector ................................................................................................................................................................... 15
Serial Port Connector .................................................................................................................................................................. 16

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Overview
The main purpose of the NeverDie® BMS is to protect the battery by disconnecting it from the rest of the system when it detects any
potentially harmful conditions, as well as provide emergency energy reserve by saving part of the battery’s capacity during normal
use. Additional functions of the Advanced BMS is to gather battery data and send it over a digital interface to a computer system for
data logging and analysis, as well as display real time data.
Installation
Since Lithionics Battery offers countless battery configurations, this document will not cover detailed installation steps and assumes
that the Battery and BMS are already installed. Please refer to your specific installation guide or contact Lithionics Battery for
installation assistance. Typically, the BMS is installed between the battery and the rest of your system, acting as an intelligent power
switch. NOTE: Do NOT attempt to bypass the BMS or tap any loads directly from any battery modules, as it could lead to permanent
battery damage and voids your battery warranty!!!
Definitions
It’s important to understand some common terms describing a lithium battery’s operation, which are often used in detailed feature
descriptions further in this document. It also helps to visualize a charge/discharge graph of a typical lithium battery, to see various
voltage points and how they relate to state of charge.
 VPC – Volts Per Cell . A Lithium Battery contains several cells connected in series. Battery voltage is a sum of all cell
voltages. LiFePO4 chemistry cells are 3.2VPC nominal (i.e. average voltage during discharge). A typical 12V battery has 4 cells
in series, also known as a “4S” configuration. Respectively, a 24V battery is 8S, while 48V batteries can be 15S or 16S
depending on the model. Since the BMS monitors and acts at the individual cell level as well as pack level, it’s more common
to refer to cell level voltages, abbreviated as VPC. For example, a fully charged and rested cell is at 3.4VPC, which means a
12V (4S) battery would be resting at 13.6V.
Picture on the left illustrates the cell level and the pack level voltages.
Due to manufacturing tolerances and environmental factors
individual cell voltages may not always be the same, so the BMS must
employ both cell level (MiniBMS®) and pack level (NeverDie® BMS)
triggers for protection events such as HVC and LVC. Our BMS also
works to minimize those voltage differences in a process called
“balancing”, which occurs at the end of each full charge cycle.
Pack level triggers are more conservative than cell level triggers to
allow for some natural imbalance in cell voltages at the top and the
bottom of the charge/discharge cycle. BMS events are triggered on
both cell level and pack level, whichever happens first.
In a 12V battery, for example, pack level and cell level triggers are:
HVC Pack Level = 14.80 V
HVC Cell Level = 3. 5 VPC
LVC Pack Level = 11.60 V
LVC Cell Level = 2.50 VPC
 Charge / Discharge Curve . One of the main advantages of a Lithium battery compared to a Lead Acid battery its
flat charge/discharge curve. This means that the battery voltage stays relatively constant for most of the charge/discharge
cycle, with sharp “knees” on both ends where voltage rises and drops very fast. Constant voltage means stable power is
supplied to loads, making them operate more efficiently. However, this also renders voltage-based SOC (state-of-charge)
measurement useless. Voltage based SOC estimates can only be done at the upper and lower “knees” where voltage change
is more pronounced. See the Charge and Discharge Curves below with explanations of usable and reserve power.

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 VC – eserve Voltage Cutoff . Typically set to 3.0VPC on voltage based BMS triggers. At this level the BMS
would shut off the battery power allowing the NeverDie® Reserve Power capacity to be stored in the battery for an
emergency, such as engine cranking. The areas shaded red in the picture below represent the Reserve Power. In Advanced
Series BMS, the RVC level can also be set based on true SOC measurement, using a Coulomb counter, which also allows for a
larger reserve power capacity if desired.
 LVC – Low Voltage Cutoff . Typically set to 2.9VPC at the pack level and 2.5VPC at the cell level. At this voltage the
battery is almost fully discharged, so the BMS shuts off the battery to prevent damage due to over-discharge.
Discharge Curve
 HVC – High Voltage Cutoff . Typically set to 3.75VPC. At this voltage level the cell is not taking any more charge,
so voltage rise becomes exponential and if left unchecked would cause permanent damage to the battery. The BMS shuts off
the battery when any cell reaches this level, allowing voltage to rest down.
 Balancing Stage . As the battery nears the end of charge the cells enter the upper knee of the charge curve, where
voltage rise becomes faster and faster. Due to individual manufacturing differences between cells, some cells reach this stage
earlier than others, causing voltage imbalances between cells. While not harmful in the short term, in the long term such an
imbalance will become more and more pronounced which eventually reduces the useful capacity of the battery. To
counteract this process the BMS performs cell balancing by slightly discharging the higher voltage cells (a process called
“shunting”), this allows the lower cells time to catch up. This process is similar to “equalization” in a Lead Acid battery but
requires more precision and controlled by the BMS on an individual cell level.
Charge Curve

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BMS Operation
The NeverDie® BMS operates by monitoring the voltage and temperature data from each individual cell and battery pack as a whole.
Cell data is then passed on to the BMS via a unique single-wire interface called OptoLoop®. Such an interface allows for a flexible
distributed design for battery packs of various voltages and capacities. OptoLoop® works by establishing circuit continuity which passes
thru all individual BMS monitoring boards installed on each cell inside the battery modules. When continuity is broken by any cell
board or wiring fault, the main BMS unit will open the main contactor as well as not allow it to close until the fault is resolved.
Below flowchart depicts typical BMS operation cycle when battery is fully depleted or at risk of overcharge by a rogue charge source.
The NeverDie® BMS does not need to intervene if the battery is cycled normally.
For simplicity reasons this flowchart only shows basic protective BMS functions based on voltage triggers. Additional BMS functions
based on temperature triggers and other advanced functions based on SOC triggers are not shown in this flowchart.
Please refer to Advanced BMS Functions chapter for details of those functions.
Turn on battery power
by short press of the Power
Button
Normal operation:
3.00 < VPC < 3.65
Press and hold
Power Button for 5
sec to turn off
battery power when
needed
During discharge
voltage drops to RVC
level. BMS triggers
RVC event and
opens the contactor
Short press of the
Power Button
reactivates BMS
contactor to access
reserve energy and
begin charging
Charge Source
activated?
As reserve gets
depleted voltage
drops to LVC level.
BMS triggers LVC
event and opens the
contactor
es
No
Attach and activate
a charge source
ASAP. Short press
the Power Button to
reactivate BMS
contactor to start
charging
During charge, if a
charge source tries
to overcharge the
battery or if cells are
imbalanced and any
one cell becomes
overcharged
HVC voltage
reached at cell
level?
Signal charge source
to pause charging
until cell voltage
recovers, promoting
cell balancing
HVC voltage
reached at pack
level?
Signal charge source
to stop charging
until battery rests
down to Float level
Did charger
fail to stop?
It’s still charging?
No
BMS triggers HVC
event and opens the
contactor, until
voltage drops or
short press of Power
Button
es
No
es es
No
Did charger
fail to stop?
It’s still charging?
es
No
BMS Operation flowchart

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SOC Gauge operation
The Advanced Series BMS includes an integrated SOC Gauge, designed to track battery state of charge (percent of usable energy left
in the battery) as well as other useful data parameters. Tracking state of charge is accomplished by a Coulomb counter, based on an
internal, high sensitivity hall-effect sensor. The SOC Gauge data will only be correct if the configuration parameters are set correctly,
which are pre-set initially by Lithionics Battery, but are user adjustable with supporting hardware. If they are ever accidently modified
a record of the default values is included in this manual for your reference. The SOC Gauge will also track and display live amperage
(A), live wattage (W), battery voltage (V), temperature (F/C), amp hours (Ah), watt hours (Wh), time remaining (d/h), etc. The meter
will be most accurate if the battery is fully charged on a regular basis. If the battery is always partially charged, then the SOC meter
reading may drift in the long term and will become less accurate. When the most
accurate measurements are required it is recommended to perform a full charge at
least weekly.
SOC Data can be observed on the optional LCD Display pod or extracted from the
BMS data interface.
The LCD Display pod has a 2-line screen capable of showing 2 data points
independently. Pressing the left button scrolls through the available data points on
upper line, pressing right button scrolls through the available data points on the
lower line. Any combination of data is possible on these 2 lines. The following list
explains all available data points:
 E █ █ █ █ █ █ F – Graphical representation of the Battery Gauge. Each of the
6 bars corresponds to approximately 17% of capacity.
 100% BAT – Digital Battery gauge. BAT level is derived from SOC minus the MinSOC setting explained in the Settings
section below, allowing for a hidden reserve
 23.4 A – Amperage. Instant current reading. The “+” sign in front of the value indicates charging current. No sign indicates
discharging current.
 20000 W – Instant Wattage reading. This power value is derived by multiplying current and voltage together. This is
useful to estimate how much instant power is passing through the battery circuit. This value can be manually converted to
horse power by the formula: HP=Watts/745.7
 39.6 V – Instant battery voltage reading.
 82F t1 – Instant temperature reading. Can be set to C or F in the Config menu. Temperature data comes from Temperature
Intervention Sensors, or from BMS internal sensor if external sensors are not present. “t1” indicates how many sensors are
present, up to 8 sensors are supported in large systems with multiple battery modules.
 100.0 Ah – Remaining Amp Hour capacity of the battery.
 3960 Wh – Remaining Watt Hour capacity of the battery. The Watt Hour value is derived by multiplying the Amp Hour
value and the Pack Voltage together. This value will be changing dynamically as voltage fluctuates with load.
 D 22.5h – Remaining time at current load level until battery is depleted. This value will be changing dynamically if load
current changes over time. When battery is charging first letter will change from D to C and displayed value will indicate
remaining time to full charge. Time counter label automatically scales to days (d) or hours (h).
 000000 – System Status Bits value. See chapters below for detailed explanation of this value.
 T0001234 – Total number of AmpHours consumed from the battery since day of manufacture. This value helps estimate
battery State of Health by extrapolating its discharge cycles over the life of the battery.
LCD pod has a backlight feature, which activates for 30 seconds after each button press, to better see the data in the dark environment.
After 30 seconds backlight turns off to avoid light pollution if LCD is installed in the sleeping compartment.
System Status bits
One of the data values in the BMS Data Stream is called System Status, where each bit represents one of the basic conditions of a
battery system in real time. In Serial/Ethernet streams this value is labeled ‘R’, located at the end of the data string, it’s 6 characters
long and coded in Hexadecimal digits ‘0-F’. Each HEX digit represents 4 bits of binary data, for a total of 24 bits of data. In CANBus
stream it’s located in the first 3 bytes of the message ID = 0x18FF98FA (Battery State). See CANBus documentation for details.
NOTE: Some of the bits represent optional BMS features, which might not be enabled in your system.

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Description of System Status bits:
HEX Digit 6 HEX Digit 5 HEX Digit 4 HEX Digit 3 HEX Digit 2 HEX Digit 1
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Bit 0 – High Voltage State . Indicates that battery voltage is above HVC, typically 3.70VPC.
Bit 1 – Charge Source Detected . Indicates that charge voltage was detected on the far side of the contactor, allowing contactor
to close even when battery is in Low Voltage state. This bit resets when battery reaches Nominal voltage.
Bit 2 – NeverDie Reserve State . Indicates that battery is in the NeverDie Reserve State, allowing access to reserve energy.
Bit 3 – OptoLoop® Cell Loop is open . Indicates that Cell Loop is open, which means one or more cells is out of normal voltage
range, or broken Cell Loop wiring between battery modules and/or NeverDie BMS unit.
Bit 4 – Reserve Voltage Range . Indicates that battery voltage is below RVC, typically 3.0VPC.
Bit 5 – Low Voltage State . Indicates that battery voltage is below LVC, typically 2.6VPC.
Bit 6 – Battery Protection State . Indicates that battery is recovering from abnormal event, such as short circuit, pre-charge
failure, or contactor failure. See additional bits below for more details.
Bit – Power Off State . Indicates that battery was turned off by a command or a button press.
Bit 8 – AUX Contacts State. State of Auxiliary contacts inside the contactor, reflects actual physical state of the main contactor.
This optional feature requires special model of the contactor with AUX contacts.
Bit 9 – AUX Contacts Error. In case of contactor welding, this bit will indicate discrepancy between expected and actual state of
contactor. It also sets Bit 6 – Battery Protection State.
Bit 10 – Pre-charge Error. Indicates that Pre-charge function failed to detect voltage rise on the load side of BMS, which could
mean a short circuit condition or other issues with load wiring. It also sets Bit 6 – Battery Protection State. This optional feature
requires Pre-charge relay and resistor to be installed inside the BMS unit.
Bit 11 – Contactor Flutter. If BMS contactor changes state 10 times over 5-minute period, BMS enters Power Off state and sets
this bit, so troubleshooting can be performed. This condition could be caused by wiring problems or other hardware issues and requires
service attention.
Bit 12 – AC Power Present. Indicates that BMS detected AC power presence, so BMS expects charging to begin shortly. This
optional feature requires special wiring inside BMS unit to connect to AC grid.
Bit 13 – TSM Charger Present. Indicates that CAN message from TSM charger was detected on CANBus interface. This indicates
TSM charger is present and has AC power. Used for troubleshooting TSM chargers.
Bit 14 – TSM Charger Error. Message received from TSM charger indicating an issue with the charger. Further analysis of CAN
data from the charger is needed to determine exact nature of the problem.
Bit 15 – Temperature Sensor Error. Indicates a problem with temperature sensor installed inside the battery module.
Temperature data from this sensor is used to cutoff battery power under extreme temperatures.
Bit 16 – AGSR State. State of optional AGSR Control circuit, used to start/stop generators when BMS is wired into supported
generator’s auto start interface.
Bit 1 – High Temperature State. Temperature detected by intervention sensor exceeded allowed threshold.
Bit 18 – Low Temperature State. Temperature detected by intervention sensor is below allowed threshold.
Bit 19 – Auxiliary Input 1 State. Reflects the state of AUXIN1 input, which is optional and application specific.
Bit 20 – Charge Disable State. Signals any charge source to stop charging the battery while this bit is set. This state is determined
by BMS logic based on multiple factors including cell level and pack level protective functions.
Bit 21 – Overcurrent State. BMS detected current higher than preset limit.
Bit 22 – Bit 23. Not used, reserved for future functions.

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Bluetooth Telemetry
Lithionics Battery has developed the Lithionics Battery Monitor application for iOS and Android mobile platforms, which
allows real time monitoring of battery data if the BMS is equipped with the optional Bluetooth BLE module. However, our Status
Code Reader function can be used even without this optional module.
The Status Code Reader function makes it easy to visualize
status of each bit by typing in the System Status value and
observing color coded table of bit values, see example
below. ou can download this application from Apple and
Google application markets on your iPhone, iPad, Android
phone or tablet.
Each active bit description is color coded in green or red,
where green indicates informational bits and red indicates
faults or critical conditions requiring attention, such as
immediate need to charge the battery.
NOTE: All 6 digits of the “R” value must be entered,
including leading zeroes to trigger decoding function.
LED Indicators
NeverDie® BMS has an LED indicator integrated into the Power/On/Off/Re-Set button on the unit itself and in some cases, there are
also optional remote LED indicators. There can be one or two remote LEDs, for Power On/Off/Alarm status and Low Battery status.
Please refer to your specific installation to check which LEDs, if any, you have available in your system.
 Power On/Off/Alarm – This LED indicator is integrated into the Power Button or could be a separate remote LED,
depending on specific installation. LED is off when BMS is turned off and battery power is disabled. LED is on when BMS is on
and battery power is on. LED flashes rapidly when BMS is in alarm state and battery power is disabled. LED blinks briefly when
BMS is on and sending telemetry data, but battery power was turned off by operator, usually this is only available in the dual
stage power up mode.
 Low Battery – This optional LED indicator is typically installed at the control panel, so the operator can see when the
battery is getting low and needs to be charged. LED turns on when battery goes below approx. 20% SOC and can be based on
pack voltage trigger of 3.05VPC or Coulomb counter value of 20%, whichever comes first. When charging is in progress LED
will turn off after voltage rises above 3.30VPC and Coulomb counter value is above 20%.
BMS Troubleshooting
Last ecorded Trouble Code . When BMS is powered on, the LCD display shows the last recorded trouble code and the
firmware version for 5 seconds, before it switches to normal data display. If you missed it, you can power cycle the BMS again and
take a snapshot of the LCD display during first 5 seconds. When contacting Lithionics Battery for support, please write down this last
recorded trouble code and the firmware version and pass this information to your support contact.
Module(s) Voltage . Most Lithionics Battery systems are built as modular assemblies, with series/parallel connected battery
modules and an external NeverDie® BMS enclosure. In such a modular architecture, troubleshooting comes down to simply checking
voltages of individual modules, and, checking continuity of all connections. A healthy and well-maintained battery would exhibit the
same or very similar voltages on all modules of the same configuration, so if you see one module’s voltage is significantly different
from the other modules, it could indicate an imbalance in the State of Charge between modules, which causes unexpected BMS events,

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since BMS protects the individual cells in the difference modules. When contacting Lithionics Battery for support, please write down
the exact voltages of each battery module and note if the measurement was taken at the end of charge or discharge, or somewhere
in between.
Negative eference wire . Make sure the BMS negative reference wire has a good solid connection to the battery’s most
negative terminal. The BMS uses this wire for its own power as well as voltage measurements. If there is a poor or loose connection,
the BMS will have unpredictable behavior. For systems utilizing the Anderson Power Products EURO DIN connector, the negative
reference wire is integrated into the wire harness provided with the system.
OptoLoop® connections . Each battery module has a normally-closed (N.C.) OptoLoop® (a.k.a. Cell Loop) output composed
of 2 light green-colored 18-gauge wires. These wires are “daisy-chained” from one battery module to the next. The OptoLoop®
connection starts and ends at the NeverDie® BMS unit. If there is ever a fault in any battery module, then its Cell Loop will go to an
open-circuit condition which communicates the fault to the NeverDie® BMS. This simple open/closed circuit fault makes diagnosing a
battery system very easy. To check the continuity of the OptoLoop® connection on each module, disconnect the light green wires from
the adjacent modules and check for continuity between the 2 wires using a DVM set to continuity checking mode, which beeps when
there is continuity between probes. Also check for overall continuity across all modules at the BMS connection points. The BMS must
sense continuity of the OptoLoop® in order to operate properly. The Opto-Loop connections points are normally either Delphi
Weatherpack connectors or located in 2 small signal pins of the Anderson EURO DIN connector plug.
Advanced BMS functions
When the BMS is initially powered on by the Power button, it performs health checks across the OptoLoop® and also checks the pack
level voltage and the State of Charge (SOC). The BMS then begins to transmit digital data onto its available interfaces, such as CAN,
RS232 or TCP/IP, depending on the specific BMS configuration. If all health checks are successful, BMS will close the main contactor
and allow use of the battery power. Some applications may require dual stage Power Up, where BMS waits for a separate command
to close the contactor. This mode can be enabled in the BMS configuration if desired.
When the main contactor is closed, and the battery is being charged or discharged, the BMS is always monitoring battery health
parameters and will open the contactor if any trouble is detected. ou can also open the contactor by holding the Power button for 3
seconds or by sending the $BATOFF command via its data interface.
Below is a detailed description of advanced BMS features and how they affect the state of the contactor. Some features depend on
setup parameters which are described in detail in the Configuration section of this user guide.
 Power On/Off – Briefly press the Power button to turn on the BMS and enable battery power. The battery can be
turned off by holding the Power button for 3 seconds, or by sending $BATOFF command via its digital interface. If BMS is
configured for dual stage power up, then first button press will turn on the BMS and second press will turn on the battery
power. In this mode the BMS is powered off by holding Power button for 10 seconds while turning off the battery power.
NOTE: Some high voltage battery systems have a separate latching BMS Power Switch used to stop quiescent load from
internal DC/DC converter. Always turn off the BMS with the Power Switch when placing the battery into storage or for
removal and/or transporting of the battery, as well as making any wiring changes!
 eserve Voltage Cutoff ( VC) – NeverDie® function. During discharge the BMS will open its contactor,
disconnecting the battery power when battery reaches the RVC level, which allows the battery to store energy reserve. The
RVC level is defined either by voltage (typically 3.0VPC or 3.1VPC) or by SOC percentage set in the BMS Configuration,
whichever comes first. Once the battery is in the RVC state you can access the reserve capacity by a short press of the Reset
button or by sending the $BATON command via digital interface. If desired, the RVC function can be disabled by setting RVC=0
in the BMS’ Configuration.
 Low Voltage Cutoff (LVC) – During discharge the BMS will open its contactor when the battery reaches the LVC
level. LVC is monitored on both pack level and cell level, using the OptoLoop® interface. The contactor remains open until the
BMS detects a charge voltage, at which point the contactor will close to allow charging. The BMS will monitor the initial charge
for expected voltage rise and will open the contactor again if voltage rise is not detected within 20 minutes, or immediately
if voltage continues to fall below LVC level. Some charging sources require to “see” the battery before allowing charging, in
which case LVC lockout can be temporarily overridden by holding down the Power button for 10 seconds while powering on
the BMS. This override will allow the contactor to close so charging can begin. If voltage rise is not detected within 20 minutes
or voltage continues to fall below LVC level, the contactor will open again to protect the battery.

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 High Voltage Cutoff (HVC) – During charging the BMS will open the contactor if any cell signals HVC voltage level
via the OptoLoop® interface. This should not happen during normal operation if charging sources are setup with correct
voltage levels. Once the charge voltage is removed, battery voltage will slowly lower to resting level, typically 3.4VPC. If your
charging source has a “float” mode, it should be set to 3.4VPC, which is a resting voltage of a fully charged cell. If your charger
has a control interface connected to the BMS, then the BMS will force the charger to stay off until voltage drops below this
“float” level.
 Temperature Based Cutoff – when temperature inside the battery goes below or above preset safe limits BMS
will open the contactor to prevent further use of the battery until temperature returns under safe limits. Different
temperature limits are enforced for charging and discharging due to nature of Lithium chemistry. Discharge safe range is -4F
to 131F, charge safe range is 32F to 113F.
 Field Control Circuit (FCC) – if your BMS is wired to your alternator’s field or regulator circuit, it will disable the
alternator’s output by opening this circuit when HVC condition is detected, to protect the battery from being overcharged.
The BMS will open this circuit 2 seconds prior to opening main contactor, allowing alternator field to discharge which protects
the alternator’s diodes from potential damage. This circuit can also be used to disable other charge sources, such as solar
controllers or inverter/charger’s charge function.
 Short Circuit Protection – The BMS will detect a possible short circuit event if the battery voltage drops below
1.75VPC, immediately disconnecting the contactor. The contactor will stay open until the BMS is power cycled or Power
button is held down for 10 seconds to reset the BMS, or charge voltage is applied to the BMS.
NOTE: The lithium battery is capable of significant power output and may maintain the voltage level during a short circuit
event, producing a very large current, capable of melting or welding connection points and damaging cables and
connectors. Even if the BMS detects short circuit and tries to open the contactor, the contactor itself might weld under
such a very large current. Make sure the battery connection is always properly fused and does not rely on the BMS alone
for short circuit protection!
 Automatic Generator Start/ estart (AGS ) – if your BMS is wired to your generator’s start circuit, it will
close the circuit to start the generator when voltage drops below 3.05VPC or BAT percentage drops below the “AGSR Lvl”
level set in BMS Configuration, whichever comes first. The AGSR circuit will open when the voltage rises above 3.5VPC after
15-minute delay, which simulates a Constant Voltage charge stage. ou can also manually turn AGSR circuit on and off by
briefly pushing Power button while the battery is turned on.
Pre-charge Control – This optional feature requires hardware implementation inside of the BMS unit. The purpose
of this feature is to reduce inrush current when closing the contactor into a capacitive load, such as an inverter or motor
controller. When the BMS is commanded to close the contactor, it will first close a small pre-charge relay in series with a pre-
charge resistor, which limits the current to a safe low level. Such a small current will safely charge the capacitive load, reducing
voltage across main the contactor, then the BMS will close the main contactor without high inrush current. Pre-charge timing
and voltage threshold are configurable, allowing fine tuning of the process in complex systems with mixed capacitive and
resistive loads. If at the end of pre-charge timer voltage threshold has not been reached, BMS will not close the contactor
and will set PRECHARGE_ERROR status flag for troubleshooting purposes. This protects the system in case of pre-charge
circuit failure or short circuit at the Load side of the BMS. NOTE: If load resistance is very low (such as a high-power resistive
load bank) then the BMS will mistake it for a short circuit. In this case you must disable the pre-charge control feature as
it was not designed for resistive loads.
 Auxiliary Contacts – This feature is part of the special type of contactors used inside the BMS unit, which has
mechanically coupled aux contacts on the same arm as the main contacts. This allows monitoring for possible welding of the
contactor in high power systems. The BMS monitors the state of aux contacts when changing state of the main contactor to
make sure there is a match between actual and the expected state of the contactor. If there is a mismatch, the BMS will
attempt to unstick the contactor by repeatedly pulsing the coil up to 10 times. If not successful, the BMS will set the
AUX_ERROR status flag for troubleshooting purposes. During normal operation the BMS will set AUX_STATE flag to indicate
current state of aux contacts, which can be interpreted as the actual state of the main contactor.
 Charger OFF control – When BMS is wired to control a charger, it will disable the charger when battery power is
commanded OFF with a long push of the Power button or the data stream command $BATOFF. This is a safety feature to
prevent chargers from outputting voltage when the battery is disconnected.
Contactor Flutter detection – if any abnormal condition, such as loose wiring or faulty equipment causes the
BMS to turn contactor on/off 10 times in a 10-minute period, then the BMS will enter the Power Off state, preventing
contactor flutter. Once the problem is investigated and addressed, hold down Power button for 10 seconds to reset the BMS,
to return to normal operation.
 Alarm Circuit – An optional wiring circuit from the BMS which can provide an audible or visual alert when BMS detects
any trouble with the battery.