BQ27520-G4: RUP_DIS set at the end of discharging during learning cycle

Hi Eugene,
Did you get a qmax update occur first? What is your discharge rate? You need to use a value between c/5 and c/10. I prefer using c/7
pls follow these steps for a learning:

- Issue a IT enable command (0x21). Then Issue a reset command (0x41)
- Discharge to empty (terminate voltage) using a constant current value between C/5 and C/7
-Rest for 5 Hours
-Charge the battery to full( charge voltage specified in DS of cell) and make sure you taper to a value below the taper current in DF
-Rest for 2 hours ( Qmax will update at this point). Update status will go from 00 to 01.
Discharge to empty using the same discharge rate as before.
Rest for 5 hours.
At the end of discharge, update status will change to 02 for system side gauge

thanks
Onyx

Hello Onix,

No, qmax update didn't occur - it was updated at relaxation stage after charging last time. And update status is still 1. Discharge rate is c/5.

For this moment (during relaxing after discharging) RUP_DIS and VOK have been cleared. But no qmax update still. I've attached log.

Best regards,

Eugene

dataram2.log

hi Eugene,
Once qmax has updated, resistance update is what needs to occur next and for that you need to use a current between c/5 and c/10. What is your design capacity and what is your discharge current.

Even though qmax updated for the previous cycle. You can just continue from with the new cycle where you discharge the battery to empty, using prefereably c/7 and then rest for 5 hours.
thanks
Onyx

Hi Onyx,

Battery capacity is 630 mAh and discharge current was C/5 at my first attempt. But as I said, RUP_DIS bit has been set and I didn't get the second qmax update.

Since qmax was updated once, following your instructions I charged the battery to full and then discharged it to empty using C/7. I've seen that ra tables have been updated few times during discharging. RUP_DIS hasn't been set this time - that's good. But now there is another problem: battery is relaxed and I'm waiting for more than 6 hours for OCV measurement. But it doesn't occur: VOK is still high. I'm attaching logs.

Best regards,

Eugene

learning2.zip

 

Waited 10 hours more and VOK was still high.

So, I've set Update status to 0 manually. Then sent IT_ENABLE and RESET. And charged battery to full. After about 1 hour of relaxation VOK has been cleared and Update status changed to 2 (not to 1!).

Does it mean, that battery successfully passed learning cycle? If not, how to restart the learning cycle correctly? Should I modify the Update status? And what does Update status mean (reference manual has very little info about it)?

thanks,

Eugene

Hi Onyx,

So, do I need to re-run the learning cycle again? If so, what is the right way to do it? Current Update status value is 2.

Thanks,

Eugene