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BQ20Z45 INIT bit

karen azores
Prodigy 30 points
Other Parts Discussed in Thread: BQ20Z45

Dear Sir,

We would like to inquire regarding the INIT bit for BQ20Z45

Our customer has asked us to simulate our battery pack with high discharge power (178W) under high ambient temperature (60degC). For this pack, we have disabled all PF settings and set our protection values to maximum especially current and temperature just to see if there would be any effect on the battery pack. We were charging at 0.63C and has set to cut-off at 0.01C.

We were able to do a continuous 3 cycle charge-discharge with no rest time in between. 

First Charge : INIT bit OK

First Discharge : INIT bit OK

Second Charge : INIT bit turns OFF when the Current becomes zero

Second Discharge : INIT bit is still OFF and only turns ON when RSOC becomes 95% (based from our Dataflash, we only have a 95% setting for TCA Clear% and FC Clear %)

Third Charge : Same as Second Charge. INIT bit turns OFF when the Current becomes zero

Third Discharge : Same as Second Discharge. INIT bit is OFF and only turns ON when RSOC becomes 95%

Now, we tried doing the same test at ambient temperature of 25degC. After removing the charger, I have allotted a 1-hour rest before I started to do discharge of 178W to see if it would affect the INIT bit but the results are the same. The INIT bit turns OFF when the current becomes zero. During the whole rest period, the iNIT bit is also OFF. INIT bit only turns ON when RSOC becomes 95%.

I have checked our previous learning cycle for this battery pack and based from the log data we never lost the INIT bit throughout the whole cycle which includes charging, rest of 2hours, discharge, 5hours rest time. And we would like to understand why the INIT bit is turning OFF? And what are the effects when this INIT bit is OFF? Will it have any effect on the fuel gauging of our battery pack?

I have attached the DF and the charge-discharge confirmation under 25degC for your reference.

Thank you sir and hoping for your immediate response.

Thank you and Best Regards,

Karen4011.17-AUG PACK1.xlsx

  • 0
    Prodigy 30 points

    Dear Sir,

    We would like to follow up on my previous concern regarding the INIT bit. Kindly help to explain the cause of the INIT bit turning OFF and what are the effects to the IC and ultimately to our battery pack in such a case where the INIT bit is turned OFF.

    In addition to this, we would also like to raise another incident where we lost the INIT bit on a different battery pack. The current set up of our testing is that the charger and the EV kit are both connected to the battery pack. 

    First I changed the DataFlash for TCA Clear %, then after changing I confirmed that INIT bit is still ON. After that, I removed the connector of the charger from the battery pack because I needed to change the charger cut-off from 0.01C to 0.05C. Then when I reconnected the charger, the INIT bit was OFF. I do not understand what exactly caused the INIT bit to disappear. Please kindly help us to understand the INIT bit concept. Would connection problem cause INIT bit to disappear? Then I also noticed that the cycle count went up to a very high number (5900+) which is an unrealistic number since the battery pack has not undergone such number of cycles. I noticed that this is a common occurrence whenever we lose the INIT bit. The cycle count rises to a very high number. Aside from the cycle count being affected, would there be any other abnormalities on the fuel gauging and functionality of the IC? Below is a screen shot of the SBS of no INIT bit however I cannot attach the SENC file.


    Then regarding the extracting of the SENC file, I checked the INIT bit is still OFF. After I finished extracting the SENC file, I entered 08 to the Send SMB command before restarting the EV software. After re-starting, I noticed that the INIT bit is back.

    We tried to reburn the extracted the SENC to the same battery pack just to see if the INIT bit would disappear but INIT bit was ON after burning the SENC. Kindly help us explain if it caused a reset on the IC.

    Thank you sir and hoping for your immediate response.

    Thank you and Best Regards,

    Karen