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EVSW for bq27425EVM

Daniel Terpstra
Prodigy 80 points

I'm evaluating the bq27425 that I've just received.  The first thing I noticed after opening the evaluation software is that the calibration tab is nowhere to be seen!  How am I supposed to calibrate my pack current, which is offset by 13mA at 1A!

  • 0
    TI__Genius 14985 points

    With no current applied does your gauge read 0mA?  You'll notice that the EVSW has no bqEASY tab or Calibration tab.  We will be releasing a standalone tool shortly called bqConfig that will guide you through the configuration and calibration of the bq27425.  The calibration section will only allow you to calibrate voltage offset and board current offset.  You will not be able to calibrate current gain because...

    This gauge doesn't require current calibration by the user.  Current measurement is calibrated at the factory to the level required for correct operation of the fuel gauging algorithm.

  • 0 in reply to dMax
    Prodigy 80 points

    Yes, with no current applied the EVSW reports 0mA.  It is at C-rate level currents (1.5A for my 1500mAh battery) that the values differ by more than 10mA.  How long might I have to wait for that standalone tool?

    Why is it that the the Dsg Current Threshold, Chg Current Threshold, and Quit Current defaults are 167mA, 133mA, and 250mA (respectively)?  The Quit Current has always been illustrated to be smaller in magnitude than both the Chg and Dsg Current Thresholds, so why the change now?  I had changed them to 90, 113, and 60mA, according to the formulas in SLUSAI6, however they appear to have been reset to the default values.  How can I change these values (again) without the gauge losing any information learned thus far?  I believe I used 0x0013 (SET_CFGUPDATE) and 0x0042(SOFT_REST) before.

    What is the purpose of using "0.1h" as a unit of measurement for these thresholds when mA would suffice and actually be understood?

  • 0 in reply to Daniel Terpstra
    Prodigy 80 points

    Is there a document, similar to SLUA450, which explains the algorithm for the bq27425?  I would like to know (among other things) what the wait times are for entering the different modes of operation.  The Chg Relax Time Period appears to be very long (greater than 30min).  I was charging at 1.5A (C-rate) and stopped at SoC 65% where it has been 'resting' for 50min.  CHG is red, DSG is green, VOK is red, OCVTAKEN is green.  I expect DSG to go red when relaxation mode is entered, which hasn't happened yet.  The change in voltage over time achieved less than 4uV/s after ~20min.

    Fullscreen 1537.May 15 2012 special export.txt Download 
    [Header]
bq EVSW Version = 0.9.86	
DeviceName = bq27425 v2.02
Time = 15/05/2012 1:47:14 PM	


[Safety(Configuration)]
Over Temp = 55.0
Under Temp = 0.0
Temp Hys = 5.0
[Charge Termination(Configuration)]
Min Taper Capacity = 25
Current Taper Window = 40
TCA Set % = 99
TCA Clear % = 95
FC Set % = 100
FC Clear % = 98
[Discharge(Configuration)]
SOC1 Set Threshold = 10
SOC1 Clear Threshold = 15
SOCF Set Threshold = 2
SOCF Clear Threshold = 5
[Power(Configuration)]
Hibernate I = 3
Hibernate V = 2550

[Manufacturer Info(System Data)]
Block A 0 = 00
Block A 1 = 00
Block A 2 = 00
Block A 3 = 00
Block A 4 = 00
Block A 5 = 00
Block A 6 = 00
Block A 7 = 00
Block A 8 = 00
Block A 9 = 00
Block A 10 = 00
Block A 11 = 00

[IT Cfg(Gas Gauging)]
User Rate-mA = 0
User Rate-mW = 0
Reserve Cap-mWh = 0
[Current Thresholds(Gas Gauging)]
Dsg Current Threshold = 90
Chg Current Threshold = 113
Quit Current = 60
[State(Gas Gauging)]
Reserve Cap-mAh = 0
Op Config = 01F8
Design Capacity = 1500
Design Energy = 5550
Terminate Voltage = 3000
Taper Current = 75
Taper Voltage = 4200
Sleep Current = 10

[R_a NVM(Ra Tables)]
Cell0 R_a 0 = 58
Cell0 R_a 1 = 58
Cell0 R_a 2 = 59
Cell0 R_a 3 = 68
Cell0 R_a 4 = 65
Cell0 R_a 5 = 71
Cell0 R_a 6 = 83
Cell0 R_a 7 = 95
Cell0 R_a 8 = 99
Cell0 R_a 9 = 101
Cell0 R_a 10 = 134
Cell0 R_a 11 = 168
Cell0 R_a 12 = 313
Cell0 R_a 13 = 831
Cell0 R_a 14 = 1329
[R_a RAM(Ra Tables)]
Cell0 R_a 0 = 58
Cell0 R_a 1 = 58
Cell0 R_a 2 = 59
Cell0 R_a 3 = 68
Cell0 R_a 4 = 65
Cell0 R_a 5 = 71
Cell0 R_a 6 = 83
Cell0 R_a 7 = 95
Cell0 R_a 8 = 99
Cell0 R_a 9 = 101
Cell0 R_a 10 = 134
Cell0 R_a 11 = 168
Cell0 R_a 12 = 313
Cell0 R_a 13 = 831
Cell0 R_a 14 = 1329

[Data(Calibration)]
CC Delta = 6.892
CC Offset = 0.000
Board Offset = 0.0
Int Temp Offset = 0.0
Pack V Offset = 5
[CC Cal(Calibration)]
CC Gain = 6.92
CC Cal Temp = 301.8

[Codes(Security)]
Sealed to Unsealed = 36720414

  • 0 in reply to Daniel Terpstra
    Prodigy 80 points

    OCVTAKEN just turned red after almost an hour.