Lithiumate Lite Overview

General description of the digital BMS for EVs

The BMS is powered:

• By the 12 V from the ignition, when the EV is on
• By the AC power whenever the EV is plugged into the wall

The BMS is connected to

• The traction pack
• The charger
• The motor controller

Measurement

• Measures and reports the cell voltages and temperatures in up to 8 banks of cells in a battery pack
• Measures and reports the battery pack current (bidirectional load current up to 900 A; charger current up to 30 A)

Evaluation

• Calculates and reports the State Of Charge of the battery pack

Management

• Balances the pack
  • Dissipative (passive) balancing
  • Top balance, voltage based

Protection

• Turns off charger if any cell voltage exceeds a maximum, or the charging current is excessive
• Requests a reduction of motor drive if the battery is nearly empty
• Requests that motor controller be turned off if any cell voltage drops below a minimum, or the discharging current is excessive
• Disables charging and/or discharging if any cell's temperature is outside a range
• Disables charging and discharging if any cell board or bank stops reporting
• Prevents driving off when the vehicle is still plugged into the AC outlet

AC power connector

• AC Line input from the vehicle's AC plug (85 to 260 Vac)
• LED to indicate that AC power is present

Charger current sensor

• 30 Adc, charger DC output current sensor

No connector assembly required:

• AC power connector is 2-piece, screw clamp, terminal block
• Charger current sensor uses ring terminals mounted on screw terminals

Ignition power input

• 12 V nominal, 50 mA nominal (no external loads)
• LED to indicate that Ignition power is present

Cable mounted current sensor

• Ready to plug-in
• Bidirectional, 900 A max

"Discharge OK" line, normally at 12 V, open when battery cannot deliver current

• Wire to the key input of the motor controller, or use to drive the main contactor
• Wire to a "Ready" lamp on dashboard

"Low Battery" line, normally at 12 V, open when battery charge is low

• Wire to the "Valet" input of the motor controller, to reduce available drive
• Wire to a relay to add resistance to the throttle, to reduce its range
• Wire to a "Reserve" lamp on dashboard

"Throttle Reduce" output, to reduce throttle range (2 or 3-wire pot, not HEPA)

• Insert in the "Wiper" line, between throttle and motor driver (for 3-wire throttle, a resistor must ve added)
• Wire to a relay to add resistance to the throttle, to reduce its range
• Isolated, for compatibility with motor drivers with pack referenced throttle

"Charge OK" line, normally at 12 V, open when battery cannot accept current

• Wire to the "Regen Enable" input of the motor controller, to disable regen
• Wire to brake pedal pot, to disable regen

"Fault" line, normally open, grounded when a fault is detected

• Wire to a "BMS fault" lamp on dashboard
• LED to indicate that there is a fault

No connector assembly required:

• Load current sensor comes with a connector
• Control connector is 2-piece, screw clamp, terminal block

The BMS uses cell boards mounted directly on prismatic cells

• Up to 200 cells in series in a pack
• Divided into banks
• Each bank betweem 2 to 20 cells in series, recommended (users have used up to 25 cells)
• Cells directly in parallel count as one cell and use just inbe cell board
• Each bank has one positive end cell board, one negative end, and the rest are mid bank cell boards
• Each cell board measures its cell's voltage and temperature
• Posive end and negative end cell boards include an isolator, to isolate the high voltage of the pack from the 12 V supply

Bank connectors

• Uses up to 4 each, RJ45 cables
• Each RJ45 cable connects the master to a breakout
• Each RJ45 cable and breakout handles 1 or 2 banks
• A breakout has 4 cables: two for positive end cell boards, 2 for negative end cell boards

No connector assembly required:

• Bank connections use off-the-shelf shielded RJ45 modular Ethernet cables (0.5 to 4 meters, as appropriate for the application)
• Complete modular cables are readily available from numerous sources
• Breakout at other end of modular cable is fully assembled

17 status LEDs on master

• "AC Power in": lit if powered by the AC line
• "Ignition power": lit if powered by the Ignition line
• "Charge OK": lit if charging is enabled
• "Discharge OK": lit if discharging is enabled
• "Warning": lit if the battery is nearly empty
• "Fault": lit if a fault was detected
• "Status": normally fully lit; in case of fault it flashes a code for the fault
• An LED for each bank indicates the satus of the communications for that bank
• Two LEDs by the USB connector flash when data is transmitted and received

Three gauges on dashboard

• Drives standard fuel gauges (emulates fuel tank "sender")
  • Configurable to match sender's characteristics (min and max resistance, direction)
  • May be configured to drive a 5 V full scale meter
• Drives meters: battery current and voltage
  • For 5 V full scale meters
  • Full scale value configurable to match full scale on meter's face plate
  • Designed to operate with popular Westach gauges
• Every controller LED function may be duplicated on dashboard with 12 V lamps

Graphics User Interface

• Computer based monitoring and configuration
• USB port for easy interface to the computer
  • Uses a standard USB cable (no adapter dongle is required)
• Windows™ user interface
  • Basic configuration takes only 4 steps
  • One screen displays the complete status of the battery and the BMS

AC power connector:

• AC power in, 85 to 265 Vac

USB connector:

• For connection to PC, during set-up and for troubleshooting

Current sensor connectors:

• Battery current sensor screw terminals, 30 A max
• Connector for prewired 900 A bidirectional load current sensor

Bank connectors:

• 4 connectors, each for 2 banks
• Each connector has 2 LEDs, one for ach bank, to indicate its status
• Uses standard shielded RJ45 modular cables

Control connector: (clockwise from top)
Two-piece terminal block, screw clamps

• Meter outputs:
  • Pack voltage meter, configurable range, for 5 Vfs voltmeter
  • Pack current meter, configurable range (may go negative), for 5 Vfs voltmeter (may be bidirectional)
  • Pack SOC meter, emulates fuel gauge sender, configurable resistance, or for 5 Vfs voltmeter
• Power outputs:
  • 12 V when powered by the AC line (0.3 A max)
  • 12 V when powered either way (1 A max if powered from the Ignition line, 0.3 A max if powered by the AC line)
  • 5 V when powered either way (50 mA max)
• Power input:
  • 12 V from the Ignition line
• Control outputs:
  • Charge OK: normally 12 V, open if charging is not allowed
  • Discharge OK: normally 12 V, open if discharging is not allowed
  • Fault: normally open, 12 V in case of fault
  • OK: normally 12 V, open in case of fault
  • Warning: normally open, 12 V at the end of battery charge
  • Throttle: normally open, gradually lower resistance at the end of battery charge