Texas Instruments bq34210-Q1 Product manual

bq34210-Q1
Technical Reference Manual
Literature Number: SLUUBE8
September 2018

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Contents
Contents
Preface ........................................................................................................................................ 6
1 General Description.............................................................................................................. 7
1.1 Gas Gauging ................................................................................................................. 7
1.1.1 CEDV Gas Gauging Operational Overview ..................................................................... 8
1.1.2 Main Fuel Gauge Registers ....................................................................................... 8
1.1.3 Capacity Learning (FCC Update)................................................................................. 9
1.1.4 End-of-Discharge (EDV) Thresholds and Capacity Correction ............................................... 9
1.1.5 EDV Discharge Rate and Temperature Compensation...................................................... 10
1.1.6 EDV Age Factor ................................................................................................... 11
1.1.7 Self-Discharge..................................................................................................... 11
1.1.8 Battery Electronic Load Compensation......................................................................... 11
1.1.9 Initial Battery Capacity at Device Reset........................................................................ 12
1.1.10 Fuel Gauge Operating Modes.................................................................................. 12
1.1.11 CEDV Smoothing ................................................................................................ 13
1.2 Accumulated Charge Measurement ..................................................................................... 14
1.3 End-Of-Service Determination............................................................................................ 15
1.3.1 Alert Config Registers ............................................................................................ 16
1.3.2 Smoothing Config Register ...................................................................................... 21
1.3.3 End-Of-Service Determination—Detailed Description........................................................ 21
2 Functional Description........................................................................................................ 31
2.1 Device Configuration....................................................................................................... 31
2.1.1 Smoothing Config Register ...................................................................................... 31
2.1.2 Operation Configuration A (Operation Config A) Register................................................... 31
2.2 External Pin Functions..................................................................................................... 32
2.2.1 Wake-Up Comparator ............................................................................................ 32
2.2.2 Autocalibration..................................................................................................... 32
2.3 Temperature Measurement............................................................................................... 33
2.3.1 Overtemperature Indication...................................................................................... 33
2.3.2 Undertemperature Indication..................................................................................... 33
2.4 Battery Condition Warnings............................................................................................... 33
2.4.1 Battery Low Warning.............................................................................................. 33
2.4.2 Battery High Warning............................................................................................. 34
2.4.3 Battery Low SOC Warning....................................................................................... 34
2.4.4 Battery Level Threshold .......................................................................................... 34
2.5 Charging and Charge Termination Indication .......................................................................... 35
2.5.1 Detecting Charge Termination................................................................................... 35
2.5.2 Charge Inhibit...................................................................................................... 35
2.6 Power Modes ............................................................................................................... 35
2.6.1 NORMAL Mode.................................................................................................... 37
2.6.2 SLEEP Mode....................................................................................................... 37
2.6.3 SHUTDOWN Mode ............................................................................................... 37
2.7 CONFIG UPDATE Mode.................................................................................................. 37
2.8 Application-Specific Information.......................................................................................... 37
2.8.1 Battery Profile Storage and Selection .......................................................................... 37
2.8.2 First OCV Measurement.......................................................................................... 38

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2.9 Additional Data Memory Parameter Descriptions...................................................................... 38
2.9.1 Calibration ......................................................................................................... 38
2.9.2 Coulomb Counter Offset (CC Offset)........................................................................... 38
2.9.3 Board Offset ....................................................................................................... 38
2.9.4 Int Temp Offset ................................................................................................... 38
2.9.5 Ext Temp Offset .................................................................................................. 38
2.9.6 Pack VOffset ...................................................................................................... 38
2.9.7 Internal Temp Model ............................................................................................. 38
2.9.8 Ext a Coef and Ext b Coef ...................................................................................... 39
2.9.9 RC0 ................................................................................................................. 39
2.9.10 Filter................................................................................................................ 39
2.9.11 Deadband ........................................................................................................ 39
2.9.12 CC Deadband .................................................................................................... 39
2.9.13 SOC Flag Configuration A (SOC Flag Config A) Register ................................................. 39
2.9.14 SOC Flag Configuration B (SOC Flag Config B) Register ................................................. 40
2.9.15 CEDV Gauging Configuration (CEDV Config) Register .................................................... 41
2.9.16 EMF ............................................................................................................... 41
2.9.17 C0 ................................................................................................................. 41
2.9.18 R0 ................................................................................................................. 42
2.9.19 T0 .................................................................................................................. 42
2.9.20 R1 ................................................................................................................. 42
2.9.21 TC ................................................................................................................. 42
2.9.22 C1 ................................................................................................................. 42
2.9.23 Age Factor ........................................................................................................ 42
2.9.24 Fixed EDV0 ...................................................................................................... 42
2.9.25 Fixed EDV1 ...................................................................................................... 42
2.9.26 Fixed EDV2 ...................................................................................................... 42
2.9.27 Battery Low % ................................................................................................... 42
2.9.28 Learning Low Temp ............................................................................................. 42
2.9.29 Overload Current ................................................................................................ 42
2.9.30 Self Discharge Rate ............................................................................................. 42
2.9.31 Electronics Load ................................................................................................. 42
2.9.32 Near Full .......................................................................................................... 42
2.9.33 Reserve Capacity ................................................................................................ 43
2.9.34 Charge Efficiency (Chg Eff)..................................................................................... 43
2.9.35 Discharge Efficiency (Dsg Eff).................................................................................. 43
2.9.36 Depth of Discharge (DOD) at EDV2........................................................................... 43
2.9.37 Design Capacity ................................................................................................. 43
2.9.38 Design Voltage ................................................................................................... 43
2.9.39 Cycle Count % ................................................................................................... 43
2.9.40 Charge Inhibit Temp Low ....................................................................................... 43
2.9.41 Charge Inhibit Temp High ...................................................................................... 44
2.9.42 Temp Hys ......................................................................................................... 44
2.9.43 Charging and Charge Termination............................................................................. 44
2.9.44 Fast Charge Current ............................................................................................ 45
2.9.45 Charging Voltage ................................................................................................ 46
2.9.46 Taper Current..................................................................................................... 46
2.9.47 Taper Voltage..................................................................................................... 46
2.9.48 Sleep Current..................................................................................................... 46
2.9.49 Bus Low Time .................................................................................................... 46
2.9.50 Offset Calibration Inhibit Temperature Low................................................................... 46
2.9.51 Offset Calibration Inhibit Temperature High .................................................................. 46
2.9.52 Sleep Voltage Time.............................................................................................. 47

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2.9.53 Sleep Current Time .............................................................................................. 47
2.9.54 Dsg Current Threshold (Discharge Detection Threshold) .................................................. 47
2.9.55 Chg Current Threshold (Charge Detection Threshold)...................................................... 47
2.9.56 Quit Current ...................................................................................................... 47
2.9.57 Discharge Relax Time .......................................................................................... 47
2.9.58 Charge Relax Time .............................................................................................. 47
2.9.59 Quit Relax Time ................................................................................................. 47
2.9.60 OT Charge ........................................................................................................ 47
2.9.61 OT Chg Recovery ............................................................................................... 48
2.9.62 OT Discharge..................................................................................................... 48
2.9.63 OT Dsg Recovery ............................................................................................... 48
3 Communications ............................................................................................................... 49
3.1 I2C Interface................................................................................................................. 49
3.2 I2C Time Out ................................................................................................................ 49
3.3 I2C Command Waiting Time .............................................................................................. 50
3.4 I2C Clock Stretching........................................................................................................ 50
4 Data Commands................................................................................................................. 51
4.1 Control()/CONTROL_STATUS(): 0x00 and 0x01...................................................................... 52
4.1.1 CONTROL_STATUS: 0x0000................................................................................... 53
4.1.2 DEVICE_NUMBER: 0x0001 ..................................................................................... 54
4.1.3 FW_VERSION: 0x0002........................................................................................... 54
4.1.4 BOARD_OFFSET: 0x0009....................................................................................... 54
4.1.5 CC_OFFSET: 0x000A............................................................................................ 54
4.1.6 CC_OFFSET_SAVE: 0x000B ................................................................................... 54
4.1.7 SET_PROFILE_1: 0x0015 ...................................................................................... 54
4.1.8 SET_PROFILE_2: 0x0016 ...................................................................................... 54
4.1.9 SHUTDOWN_ENABLE: 0x001B................................................................................ 54
4.1.10 SHUTDOWN: 0x001C........................................................................................... 54
4.1.11 ACCUM_DSG_EN: 0x001E .................................................................................... 54
4.1.12 ACCUM_CHG_EN: 0x001F .................................................................................... 54
4.1.13 IGNORE_SELFDSG_EN: 0x0020 ............................................................................ 55
4.1.14 PIN_CONTROL_EN: 0x0022................................................................................... 55
4.1.15 CAL_TOGGLE: 0x002D......................................................................................... 55
4.1.16 SEAL: 0x0030 .................................................................................................... 55
4.1.17 EOS_START_LEARN: 0x0039................................................................................. 55
4.1.18 EOS_ABORT_LEARN: 0x003A................................................................................ 55
4.1.19 EOS_RCELL_RRATE_LEARN: 0x003B...................................................................... 55
4.1.20 EOS_WARN_CLEAR: 0x003C................................................................................. 55
4.1.21 EOS_INITIAL_RCELL: 0x003E ................................................................................ 55
4.1.22 EOS_INITIAL_RRATE: 0x003F ................................................................................ 55
4.1.23 RESET: 0x0041 .................................................................................................. 55
4.1.24 ACCUM_RESET: 0x004B....................................................................................... 55
4.1.25 GAUGING_STATUS: 0x0056 .................................................................................. 56
4.1.26 ManufacturingStatus(): 0x57.................................................................................... 56
4.1.27 ALERT_SET: 0x0068............................................................................................ 57
4.1.28 ALERT_RESET: 0x0069........................................................................................ 57
4.1.29 EDV_Threshold: 0x0073 ........................................................................................ 57
4.1.30 EXIT_ CAL: 0x0080.............................................................................................. 57
4.1.31 ENTER_CAL: 0x0081 ........................................................................................... 57
4.1.32 ENTER_CFG_UPDATE: 0x0090............................................................................... 57
4.1.33 EXIT_CFG_UPDATE_REINIT: 0x0091 ....................................................................... 57
4.1.34 EXIT_CFG_UPDATE: 0x0092.................................................................................. 57
4.2 Temperature(): 0x06 and 0x07 ........................................................................................... 57

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4.3 Voltage(): 0x08 and 0x09 ................................................................................................. 58
4.4 BatteryStatus(): 0x0A and 0x0B.......................................................................................... 58
4.5 Current(): 0x0C and 0x0D................................................................................................. 58
4.6 RemainingCapacity(): 0x10 and 0x11 ................................................................................... 58
4.7 FullChargeCapacity(): 0x12 and 0x13................................................................................... 58
4.8 AverageCurrent(): 0x14 and 0x15........................................................................................ 59
4.9 AverageTimeToEmpty(): 0x16 and 0x17................................................................................ 59
4.10 AverageTimeToFull(): 0x18 and 0x19................................................................................... 59
4.11 AccumulatedCharge(): 0x1A and 0x1B.................................................................................. 59
4.12 AccumulatedChargeTime(): 0x1C and 0x1D ........................................................................... 59
4.13 LastAccumulatedCharge(): 0x1E and 0x1F............................................................................. 59
4.14 LastAccumulatedChargeTime(): 0x20 and 0x21....................................................................... 60
4.15 AveragePower(): 0x24 and 0x25......................................................................................... 60
4.16 InternalTemperature(): 0x28 and 0x29 .................................................................................. 60
4.17 CycleCount(): 0x2A and 0x2B............................................................................................ 60
4.18 RelativeStateOfCharge(): 0x2C and 0x2D.............................................................................. 60
4.19 StateOfHealth(): 0x2E and 0x2F ......................................................................................... 60
4.20 ChargingVoltage(): 0x30 and 0x31 ...................................................................................... 60
4.21 ChargingCurrent(): 0x32 and 0x33....................................................................................... 60
4.22 BLTDischargeSet(): 0x34 and 0x35 ..................................................................................... 60
4.23 BLTChargeSet(): 0x36 and 0x37......................................................................................... 60
4.24 OperationStatus(): 0x3A and 0x3B ...................................................................................... 61
4.25 DesignCapacity(): 0x3C and 0x3D....................................................................................... 61
4.26 ManufacturerAccessControl(): 0x3E and 0x3F......................................................................... 61
4.27 MACData(): 0x40 through 0x5F .......................................................................................... 61
4.28 MACDataSum(): 0x60 ..................................................................................................... 61
4.29 MACDataLen(): 0x61 ...................................................................................................... 62
4.30 EOSLearnStatus(): 0x64 and 0x65 ...................................................................................... 62
4.31 EOSSafetySatus(): 0x66 and 0x67 ...................................................................................... 64
4.32 EOSStatus(): 0x68 ......................................................................................................... 65
4.33 AnalogCount(): 0x79....................................................................................................... 66
4.34 RawCurrent(): 0x7A and 0x7B............................................................................................ 66
4.35 RawVoltage(): 0x7C and 0x7D ........................................................................................... 66
4.36 RawIntTemp(): 0x7E and 0x7F........................................................................................... 66
4.37 RawExtTemp(): 0x80 and 0x81 .......................................................................................... 66
5 Data Memory Interface ........................................................................................................ 67
5.1 Accessing the Data Memory.............................................................................................. 67
5.2 Device Access Modes ..................................................................................................... 67
5.3 Sealing and Unsealing Data Memory Access.......................................................................... 67
6 Data Memory Summary....................................................................................................... 68
7 Application Example........................................................................................................... 81
7.1 Data Memory Parameter Update Example ............................................................................. 81
7.2 GAUGEPARCAL ........................................................................................................... 82
Revision History.......................................................................................................................... 83

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Preface
Read This First
SLUUBE8–September 2018
Preface
This manual discusses the modules and peripherals of the automotive-qualified AEC-Q100, Grade 3
bq34210-Q1 fuel gauge, and how each is used to build a complete battery pack fuel gauge solution. For
further information, refer to the bq34210-Q1 Automotive 1-Series Cell System-Side CEDV Fuel Gauge for
Rarely Discharged Batteries Data Sheet (SLUSCG1).
Formatting in This Document
The following formatting convention is used in this document:
• SBS commands: italics with parentheses and no breaking spaces; for example, RemainingCapacity()
• Data memory: italics,bold, and breaking spaces; for example, Design Capacity
• Register bits and flags: italics and brackets; for example, [TDA]
• Data memory bits: italics and bold; for example, [LED1]
• Modes and states: ALL CAPITALS; for example, UNSEALED
Trademarks
MathCAD is a trademark of MathSoft, Inc.
All other trademarks are the property of their respective owners.
Glossary
http://www.ti.com provides a Battery Glossary on the Battery Management FAQ page and the TI Glossary.
Related Documentation from Texas Instruments
To obtain a copy of any of the following TI documents, click on the links below:
1. bq34210-Q1 Automotive 1-Series Cell System-Side CEDV Fuel Gauge for Rarely Discharged Batteries
Data Sheet (SLUSCG1)
2. Going to Production with the bq275xx Application Report (SLUA449)
3. Host System Calibration Method Application Report (SLUA640)
For more documentation and product information, go to the bq34210-Q1 product page or to the TI Web
site at www.ti.com.

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General Description
Chapter 1
SLUUBE8–September 2018
General Description
The bq34210-Q1 fuel gauge incorporates gas gauging and an End-of-Service (EOS) Determination
function to use with a 1-series Li-Ion or Lithium Iron Phosphate (LiFePO4) rechargeable cell or a Nickel
metal hydride (NiMH) based pack with a configuration of 3-series cells.
The gas gauge uses Compensated End-of-Discharge Voltage (CEDV) gauging technology to accurately
predict the battery capacity and other operational characteristics of the battery. It can be interrogated by a
system processor to provide cell information, such as remaining capacity, full charge capacity (FCC), time-
to-empty (TTE), and relative state-of-charge (RSOC), and provide an interrupt signal to the processor.
The integrated EOS Determination function is specifically intended for applications where the battery is
rarely discharged, such as eCall systems, uninterruptible power supplies (UPS), enterprise server backup
systems, and telematics or telecommunications backup modules. In such systems, the battery may remain
in a fully (or near fully) charged state for much of its lifetime, with it rarely or never undergoing a significant
discharge. If the health of the battery in such a system is not monitored regularly, then it may degrade
beyond the level required for a system backup/discharge event, and thus fail precisely at the time when it
is needed most. Monitoring the battery enables the system to take action before the failure occurs.
The EOS Determination function monitors the health of the battery by using infrequent learning phases,
which involve a controlled discharge of ~1% capacity, and provides an alert to the system when the
battery is approaching the end of its usable service. By coordinating battery charging with the learning
phases, the battery capacity available to the system can be maintained above a preselected level to avoid
compromising the ability for the battery to support a system discharge event.
Information is accessed through a series of commands, called Data Commands, and indicated by the
general format Command(). Read and write information within the device control and status registers, as
well as its data memory locations are accessed through these commands. Commands are sent from the
system to the gauge using the I2C serial communications engine, and can be run during application
development, system manufacturing, or end-equipment operation.
The fuel gauge measures charge and discharge activity by monitoring the voltage across a small-value
series sense resistor (5 mΩto 20 mΩ, typical), which may be used in a low-side (at the CELL- connection)
or a high-side (at the CELL+ connection) configuration.
The external temperature sensing is optimized with the use of a high-accuracy negative temperature
coefficient (NTC) thermistor with 25°C resistance (R25) = 10.0 kΩ±1% and beta value (B25/85, resistance
at 25°C and at 85°C) = 3435 kΩ± 1% (such as Semitec NTC 103AT). Alternatively, the fuel gauge can be
configured to use its internal temperature sensor or receive temperature data from the host processor.
The fuel gauge uses temperature to monitor the battery-pack environment, which is used for gas gauging
and cell protection functionality.
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL,
SLEEP, and SHUTDOWN. The fuel gauge passes automatically between these modes (except for
SHUTDOWN exit, which needs an external stimulus), depending upon the occurrence of specific events,
though a system processor can initiate some of these modes directly. The device also includes a CONFIG
UPDATE mode, which is generally used during initial setup to update various RAM-based parameters
used by the gauge.
1.1 Gas Gauging
The bq34210-Q1 device features the Compensated End-of-Discharge Voltage (CEDV) gauging algorithm,
capable of gauging a maximum capacity of 32 Ah.
Figure 1-1 shows the operational overview of the bq34210-Q1 fuel gauge.

Charge
Efficiency
Compensation
Charge
Current
+
Inputs
Remaining
Capacity
(RC)
Discharge
Current
Temperature
Compensation
Self-Discharge
Timer
– –
≤
+
Full
Charge
Capacity
(FCC)
Discharge
Count
Register
(DCR)
Qualified
Transfer
Temperature, Other Data
Main Counters and
Capacity Reference (FCC)
Outputs
Chip-Controlled
Available Charge
LED Display
Two-Wire
Serial Port
– ++
Battery Electronics
Load Estimate
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General Description
Figure 1-1. bq34210-Q1 CEDV Gas Gauging Operational Overview
1.1.1 CEDV Gas Gauging Operational Overview
The bq34210-Q1 device accumulates the measured quantities of charge and discharge and estimates
self-discharge of the battery. The bq34210-Q1 device compensates the charge current measurement for
temperature and the state-of-charge of the battery. The device also adjusts the self-discharge estimation
based on temperature. The initial battery state-of-charge estimation on first insertion of the battery pack in
the system may display a factor of the true value; the system must go through a full charge and then a full
discharge cycle before the correct full-charge capacity (FCC) is estimated.
The main charge counter, RemainingCapacity() (RC) register, represents the available capacity or energy
in the battery at any given time. The bq34210-Q1 device adjusts RC for charge, self-discharge, and other
compensation factors. The information in the RC register is accessible through the I2C interface. The
FullChargeCapacity() (FCC) register represents the initial or last measured full discharge of the battery. It
is used as the battery full-charge reference for relative capacity indication. FCC is accessible through the
I2C interface.
1.1.2 Main Fuel Gauge Registers
Remaining Capacity (RC) — Remaining capacity in the battery
RC represents the remaining capacity in the battery. The bq34210-Q1 device computes RC in units
of mAh.
RC counts up during charge to a maximum value of FCC and down during discharge and self-
discharge to a minimum of 0. In addition to charge and self-discharge compensation, the bq34210-
Q1 device calibrates RC at three low-battery-voltage thresholds, EDV2, EDV1, and EDV0. This
provides a voltage-based calibration to the RC counter.
Design Capacity (DC) — User-specified battery full capacity

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General Description
DC is the user-specified battery full capacity. It is calculated from Design Capacity mAh and is
represented in units of mAh. It also represents the full-battery reference for the absolute display
mode.
Full Charge Capacity (FCC) — Last measured discharge capacity of the battery
FCC is the last measured discharge capacity of the battery. It is represented in units of mAh. On
initialization, the bq34210-Q1 device sets FullChargeCapacity() to the data memory value stored in
Full Charge Capacity (FCC). During subsequent discharges, the bq34210-Q1 device updates
FullChargeCapacity() with the last measured discharge capacity of the battery. Once updated, the
bq34210-Q1 device writes the new FullChargeCapacity() value to data memory in mAh to Learned
Full Charge Capacity.FullChargeCapacity() represents the full battery reference for the relative
display mode and relative state-of-charge calculations.
1.1.3 Capacity Learning (FCC Update)
An FCC update occurs if the battery discharges from RC ≥FCC –Near Full to the EDV2 voltage
threshold with the following conditions:
• No valid charge activity occurs during the discharge period. A valid charge is defined as a charge of
10 mAh into the battery.
• No more than 256 mAh of self-discharge or battery load estimation occurs during the discharge period.
• The temperature does not drop below the low temperature thresholds programmed in Low Temp
during the discharge period.
• The battery voltage reaches the EDV2 threshold during the discharge period and the voltage is greater
than or equal to the EDV2 threshold minus 256 mV when the bq34210-Q1 device detected EDV2.
• Current remains ≥3C/32 when EDV2 is reached.
• No overload condition exists when EDV2 threshold is reached or if RC has dropped to
Battery Low % × FCC.
The bq34210-Q1 device sets [VDQ] = 1 in OperationStatus() when a discharge begins. The bq34210-Q1
device sets [VDQ] = 0 if any disqualifying condition occurs. One complication may arise regarding the
state of [VDQ] if [CSYNC] is set in CEDV Gauging Configuration. When [CSYNC] is enabled,
RemainingCapacity() is written to equal FullChargeCapacity() on valid primary charge termination. This
capacity synchronization is done even if the condition RC ≥FCC –Near Full is not satisfied at charge
termination.
FCC cannot be reduced by more than 256 mAh or increased by more than 512 mAh during any single
update cycle. If [FCC_LIMIT] is set in CEDV Gauging Configuration, then FCC cannot learn above the
Design Capacity mAh. The bq34210-Q1 device saves the new FCC value to the data memory within 4 s
of being updated.
1.1.4 End-of-Discharge (EDV) Thresholds and Capacity Correction
The bq34210-Q1 device monitors the battery for three low-voltage thresholds: EDV0, EDV1, and EDV2.
If the [EDV_CMP] bit in CEDV Gauging Configuration is clear, fixed EDV thresholds may be
programmed in Fixed EDV0,Fixed EDV1, and Fixed EDV2 in mV.
If the [EDV_CMP] bit in CEDV Gauging Configuration is set, automatic EDV compensation is enabled
and the bq34210-Q1 device computes the EDV0, EDV1, and EDV2 thresholds based on values stored in
the selected CEDV profile in data memory and the battery's current discharge rate and temperature. If the
[FIXED_EDV0] bit in CEDV Gauging Configuration is also set, then the EDV0 threshold will be set to the
programmed Fixed EDV0, and the EDV1 and EDV2 compensated thresholds will not go below the
programmed Fixed EDV0.
The bq34210-Q1 device disables EDV detection if current exceeds the Overload Current threshold. The
bq34210-Q1 device resumes EDV threshold detection after current drops below the Overload Current
threshold. Any EDV threshold detected is reset after charge is applied and [VDQ] is cleared after 10 mAh
of charge.
The bq34210-Q1 device uses the EDV thresholds to apply voltage-based corrections to the RC register
(see Table 1-1).

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General Description
Table 1-1. State-of-Charge Based on Low Battery
Voltage
THRESHOLD RELATIVE STATE OF CHARGE
EDV0 0%
EDV1 3%
EDV2 Battery Low %
The bq34210-Q1 device performs EDV-based RC adjustments with current ≥C/32. No EDVs are set if
current < C/32. The bq34210-Q1 device adjusts RC as it detects each threshold. If the voltage threshold is
reached before the corresponding capacity on discharge, the bq34210-Q1 device reduces RC to the
appropriate amount, as shown in Table 1-1.
If an RC % level is reached on discharge before the voltage reaches the corresponding threshold, then
RC is held at that % level until the threshold is reached. RC is only held if [VDQ] = 1, indicating a valid
learning cycle is in progress. If Battery Low % is set to 0, EDV1 and EDV0 corrections are disabled.
1.1.5 EDV Discharge Rate and Temperature Compensation
If EDV compensation is enabled, the bq34210-Q1 device calculates battery voltage to determine EDV0,
EDV1, and EDV2 thresholds as a function of battery capacity, temperature, and discharge load. The
general equation for EDV0, EDV1, and EDV2 calculation is as follows:
EDV0,1,2 = n (EMF × FBL – |ILOAD| × R0 × FTZ) (1)
• EMF is a no-load cell voltage higher than the highest cell EDV threshold computed. EMF is
programmed in mV in the CEDV profile EMF.
• ILOAD is the current discharge load magnitude.
• n = the number of series cells. In the bq34210-Q1 case, n = 1.
• FBL is the factor that adjusts the EDV voltage for battery capacity and temperature to match the no-
load characteristics of the battery.
FBL = f (C0, C + C1, T) (2)
• C (either 0%, 3%, or Battery Low % for EDV0, EDV1, and EDV2, respectively) and C0 are the
capacity-related EDV adjustment factors. C0 is programmed in the CEDV profile C0. C1 is the desired
residual battery capacity remaining at EDV0 (RC = 0). The C1 factor is stored in the CEDV profile C1.
• T is the current temperature in °K.
• R0 × FTZ represents the resistance of a cell as a function of temperature and capacity.
FTZ = f (R1, T0, C + C1, TC) (3)
• R0 is the first order rate dependency factor stored in the CEDV profile R0.
• T is the current temperature; C is the battery capacity relating to EDV0, EDV1, and EDV2.
• R1 adjusts the variation of impedance with battery capacity. R1 is programmed in the CEDV profile R1.
• T0 adjusts the variation of impedance with battery temperature. T0 is programmed in the CEDV profile
T0.
• TC adjusts the variation of impedance for cold temperatures (T < 23°C). TC is programmed in the
CEDV profile TC.
The graphs below show the calculated EDV0, EDV1, and EDV2 thresholds versus capacity using the
typical compensation values for different temperatures and loads for a Li-Ion 18650 cell. The
compensation values vary widely for different cell types and manufacturers and must be matched exactly
to the unique characteristics for optimal performance.