CCS/BQ40Z60: How do SOH, RSOC and ASOC update?

Hi,

The TI engineers are at a customer event. Replies to questions will be delayed by 2 days.

Hi Emma,

1. Any case where FCC is updated will get an update for SOH. If FCC is same or higher than design capacity your SOH can get locked to 100%

2. SOH is an indication of how the battery ages by tracking FCC changes

Previously, the SOH of a battery was
typically represented by the actual runtime FullChargeCapacity/Design Capacity (or FCC/DC). Using the
runtime FCC, however, was not a very good representation for the state-of-health because the runtime
FCC reflects the usable capacity under load. A high current load reduces the runtime FCC. If using just
the FCC/DC calculation for SOH, the SOH under high load will be worse than the SOH under typical load.
However, a smaller usable capacity at high load does not mean the SOH of a battery is degraded. This is
the same when FCC is reduced at a lower temperature.
The bq40z60 implementation of state-of-health addresses these issues. It provides the SOH of the
battery through an SBS command, SOH(). The SOH() is calculated using the FCC simulated at 25°C with
current specified by SOH Load Rate. The SOH Load Rate can be set to the typical current of the
application, and it is specified in hour-rate (that is, Design Capacity/SOH Load Rate will be the current
used for the SOH simulation). This data flash setting is used for SOH() calculation only. This SOH FCC is
updated at the same time ASOC and RSOC are updated. Since this implementation removes the variation
of current or temperature, it is a better representation of a battery’s state-of-health. The SOH FCC is
available on MAC StateofHealth().

3. RSOC and ASOC are continuously updated in chg, dsg and when OCV is taken in relax.

Hi Batt:

    Thanks for answering my question once you finished your task!

    1, I got it that SOH will update while RSOC and ASOC update because SOH FCC update time is aligning the time RSOC and AOSC update. Is it right? Is SOH FCC also related to Qmax? SOH FCC only can decrease while Qmax decreases after update? 

2, When does RM update? what condition?

3, When BQ40Z60 is used normally that means after learning cycle in prototype stage, which flag can indicate Qmax update?

Thanks very much!

Emma W

Hi Batt:

    I have some other questions. Could you help give me some idea?

Thanks very much!

Emma