BQ3050EVM-001: Charging and Discharging Fails

Hello Bhupendra,

The load must be connected to Pack+ and Pack -, not to Battery

Same with charger.

Also make sure that the current reading is shown correctly, otherwise it is an indication that something is not connected correctly

yes Shirish,

Load Connected to PACK+ / PACK- Only . Sorry for my wrong Terminology. Here is the Setup, FYR.

Connections are fine and checked Once again.

While Discharging it Takes around 1.9A for just sec and goes into CUV Condition , disabling FET to stop discharge. ( Strange,  CUV Condition occurs without crossing Cell CUV threshold   ). 

IF I connect 4P to PACK+ and 1N to PACK-  ( YELLOW Connector in setup ) then Everything works fine.  

Hello Bhupendra,

Connecting 4P to PACK+ will bypass the FET. Once CUV is triggered, I would check the actual voltages on each of the cells and see if any of them are below CUV threshold. You may need to bypass FET to check this because the voltage will recover quickly after CUV. Bypassing the FET will prevent recovery and allow you enough time to measure.

Hello Shirish,

We checked the Voltage on Every Cell while connecting Load and @ No Load Condition.  Cell voltage are fine and same as we read on BQEVSW Software.
Not able to understand why CUV happens before CUV threshold ? 

Do you want me bypass FET by connecting 4P to PACK+ ? we already have such two ( Bypassed FET ) Battery in the Field. 
Only Difference is PRES pin was NOT Connected to PACK- pin.

Hello Bhupendra,

Can you send a SBS log from bqEVSW when you get into CUV condition? System present must be active when a load is connected.

Hello Shirish,

CUV Condition Remains always. Either Load / Charger is connected OR not connected. Charger is not able to charge as Battery is not detected due to CUV condition ( Discharge FET OFF). 

bq EVSW Version: 0.9.80 for bq3050 v0.02	
Device: bq3050 R0, FW version: V0_02_BLD0003
10/21/2022 11:39:38 AM	
           
Design Capacity: 6900 mAH
Design Voltage: 14400 mV
Specification Info: 0031 hex
Manufacture Date: 01-Jul-2022 
Serial number: 0001 
Manufacturer Name: SPARK 
Device Name: bq3050               
Device Chemistry: LION 

Sample	Stamp	~Elapsed(s)	ManufAccess	RemCapAlarm	RemTimeAlarm	BattMode	@Rate(@)	@TimeFull	@TimeEmpty	@RateOK	Temperature	Voltage	Current	AvgCurr	MaxErr	RSOC	ASOC	RemCap	FullChgCap	RunTimeEmpty	AvgTimeEmpty	AvgTimeFull	ChgCurr	ChgVolt	BattStat	CycleCnt	CellV4	CellV3	CellV2	CellV1	FETStatus	SafetyAlert	SafetyStat	PFAlert	PFStat	OpStat	ChgStat	TempRng	PendEDV	ManuFacStat
1	11:40:13 AM	0	0000	285	10	0081	0	65535	65535	1	31.55	14828	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3720	3704	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000
2	11:40:48 AM	35	0000	285	10	0081	0	65535	65535	1	31.55	14828	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3720	3703	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000
3	11:41:23 AM	70	0000	285	10	0081	0	65535	65535	1	31.65	14828	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3720	3704	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000
4	11:41:58 AM	105	0000	285	10	0081	0	65535	65535	1	31.65	14829	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3720	3704	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000
5	11:42:33 AM	140	0000	285	10	0081	0	65535	65535	1	31.65	14829	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3720	3704	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000
6	11:43:08 AM	175	0000	285	10	0081	0	65535	65535	1	31.65	14827	3	3	100	0	0	0	4596	65535	65535	65535	1600	16500	0AD0	10	3709	3719	3703	3696	0004	0000	0080	0000	0000	8060	0200	0008	13600	0000

SBS Log File attached here with.

To Remove CUV Condition , Tried Charging Battery by connecting 4P and 1N directly to the charger , and charged upto the state where FD is cleared and FC is Set. There may be some glitches , but ignore it as i have some connection trials.

See the Charge Log :  /cfs-file/__key/communityserver-discussions-components-files/196/ChargeSBSLog.log

Then Charger Removed ,4P & 1N connection Removed from PACK+/PACK-  , and 2A RES Load is connected to PACK terminals to create CUV Condition . after connecting LOAD in few Seconds , CUV Condition Occurs.  NSee the Discharge Log : /cfs-file/__key/communityserver-discussions-components-files/196/DischargeSBSLog.log

One Point I noticed here is : In Both the cases Charge / Discharge condition Current values appears wrong on BQEVSW application compared to Ammeter. Actual DisCharging current was 2A but was showing 4.8A.  

Hello Bhupendra,

The discharge and charge voltages do not match.

The logging interval is set to 35 seconds. The default of 4 seconds will capture the condition much better. I would set it to 1s if the CUV condition is seen within 10 seconds

Shirish said:

The discharge and charge voltages do not match.

Pls, Can you elaborate this ? 

Once again i repeated the steps and here is Discharge Cycle Log with 1 Sec interval. Same setup. Then Connecting 2A Load. ( also i have done Current recalibration this time ). Surprisingly , CUV Worked this. VDQ was set at this time. here is the Log File.

 /cfs-file/__key/communityserver-discussions-components-files/196/5127.DischargeSBSLog.log

  One Point I notice here is : Cell balancing , after connecting Load we see 400mV Difference between Cell1-4 to Cell 2-3.   upon CUV Condition all cell voltage seems align. 

Yes Shirish,

Can you point out reason for cell out of balance during discharge only ?  As per cell balance windows it should be around 100mV.

Hello Bhupendra,

Cell balancing is active only during charging. You will need to charge until it balances. There is a limit to how much balancing is possible based on how much current passes through the bleed FETs. It is normal for large imbalances to cause such issues. Are these old cells?

Thanks shirish,

Cell are very much new. Just One month Back purchase.

I think It may be because of Higher discharge LOAD current (>= 2.1A).  Should I change those 2 Cells which has Higher imbalances ?