BQ34Z100-G1: RUP_DIS Flag asserting at C/5 DSG on learned pack

Designing a 22000mAh battery pack with bq34z100-g1

Expect up to 110A sustained currents as this is a LiPo pack for heavy octocoptors

Design procedure:

• Designed, fabricated, and assembled PCB

• Updated firmware to bq34z100_G1_v0_16_build_17.srec

• Updated bqstudio with the latest chemistry options

• Set the appropriate flash defaults in the bq fuel gauging chip for basic functionality

• Determined a chemistry match by following the insructions for the GPCCHEM tool

• Followed the charge, rest, C/10 discharge profile

• Successfully obtained a sutiable ChemID of 1530 with Max DOD error of 1.63% and Max R deviation ratio 0.8

• Instrumentation was performed with a Yokogawa WT310 power meter for optimal accuracy

• Re-flashed bq part with stock firmware

• Updated chemistry of bq part to 1530

• Updated flash parameters of bq part with a current scaling factor of 4:

• Taper current = 110mA (scaling factor of 4 so this equates to 440mA)

• Min Taper Capacity = 6mAh (scaling factor of 4 so this equates to 24mA)

• Cell Taper Voltage = 40mV

• FC Set% = -1

• CC Threshold = 5500mAh (scaling factor of 4 so this equates to 22000mA)

• Design Capacity = 5500mAh (scaling factor of 4 so this equates to 22000mA)

• Design Energy = 20159mWh ([21793; single cell capacity] / [4; scaling factor] x 3.7V)

• Design Energy Scale = 1 (can’t scale up because max value in register is 32767)

• VOLSEL = 1

• RMFCC = 1

• Number of series cell = 6

• Cell terminate voltage = 3000mV

• Dsg Current Threshold = 25mA (scaling factor of 4 so this equates to 100mA)

• Chg Current Threshold = 25mA (scaling factor of 4 so this equates to 100mA)

• Quit Current = 10mA (scaling factor of 4 so this equates to 40mA)

• Qmax Cell 0 = 5434 (scaling factor of 4 so this equates to 21736mAh)

• Calibrated voltage

• Calibrated current with a scaling factor of 4

• Performed a successful learning cycle by following the instructions

• Started with a fully discharged and rested battery

• Charged at C/2 until taper; FC was asserted and charging was stopped;

• Relaxed 2hrs

• DSG at C/10 until empty

• Relaxed 5 hrs

• Achieved learning status of 0x06

• Ra tables updated appropriately

• Created golden image

• Saved .gg.csv file from above; set update status to 0x02, cycle counts to zero, lifetimes to defaults

• A clean/default srec imported on the device

• Chemistry updated on the device

• Imported .gg.csv file to device

• Calibrated voltage

• Calibrated current with a scaling factor of 4

• Saved this .srec as a golden image

• Re-programmed bq part with this golden image, enabled IT

Validation:

• See if the bq part updates the Ra tables with a C/5 DSG rate

• Started with an empty, rested pack

• Charged at C/2 until FC asserted

• Relaxed 2hrs

• DSG at a C/5 rate and watch Ra tables

PROBLEMS:

• The RUP_DIS flag asserted during DSG at 84% SOC for some reason and remained asserted down to 0%

• Note: After I noticed this I did end up bumping the DSG rate up to 1.3C for a few minutes to just empty the battery and then decided to resume at C/5 just to complete the test. Nonetheless the RUP_DIS flag asserted before this happened.

• Subsequent attempts with this golden image have produced the same problem. I also tried to use the GPCRA0 tool (not including this data right now) to see if I could get better pre-programmed Ra coefficients but the problem persists.

I would like the bq part to work with 5C discharge rates but can't get it to behave with even C/5 rates right now. What would be the next steps to getting it to perform appropriately in this usage scenario?

Included are the golden .srec and the .gg.csv for the bq part before performing the test  and log data from the above test.

/cfs-file/__key/communityserver-discussions-components-files/196/TestFiles.zip