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  • TI Thinks Resolved

BQ27426EVM-738: Battery Learning Cycle is canceled using Battery Management Studio

Prodigy 40 points

Replies: 2

Views: 45

Part Number: BQ27426EVM-738

I'm currently trying to evaluate the Fuel Gauge BQ27426 using the dedicated EVM-Board.

To test the board I'm using a ASR00008 Battery (available from mouser, digikey, etc.) and the battery charger evaluation board BQ25122 EVM.

Though charging/discharging of the battery works in principle, I wanted to use the "Battery Management Studio" to teach the BQ27426 the battery characteristics.

To achieve this I started the "Learning Cycle", using 2 relay circuits.

Discharging the battery works propperly (verified with multimeter/oscilloscope measurements during the cycle).

The "Relaxing" cycle is entered (this works fine in principle, however the maximum time of 360mins seems awfully long for such a small (1100mAh) battery).

Afterwards the charging cycle is started and the battery is charged. However after some time the charge cycle is canceled and the learning cycle is aborted.

The error message is either:

"QMAX_UP:Not Set"

Or:

"RUP_DIS / RDIS: not clear"

The according register settings are shown below:

It seems to me like the QMAX_UP is "0" which should be the case to enter the learning cycle.

What am I missing? Do I need to unseal the device first to enter "learning Mode"?

Or is this the wrong approach to begin with?

  • In reply to Daniel Bruch:

    Hi Daniel

    Did you run our online tool gpcchem to determine if the bq27426 is a good fit for your cells? Learning will fail if  one of the three default chem id is not a good fit.

    Also, when you start the learning cycle, did you set update status to 03.  When learning completes , update status will be 01.

    You can also try learning independent of the plug in, ie try doing the learning manually by:

    discharge to empty

    rest 5 hours,

    charge to full

    rest two hours

    discharge to empty 

    rest 5hours

    5 hours is not too much time for a battery of your capacity to rest.

    thanks

    Onyx

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