BQ35100: Accumulated Capacity

Jorg

Part Number: BQ35100

Dear TI-team,

While studying the ACC mode of the BQ35100 I found one thing unclear.
For calculating the remaining battery capacity you should read the design capacity and distract the accumulated capacity.

As refered to the TRM:

"When the GE pin is asserted, the device will update AccumulatedCapacity() from the value stored in data flash. When ControlStatus() [GA] is set, the device adds each coulomb counter measurement to the value of AccumulatedCapacity(). "

Since accumulatedCapacity(); provides an unsigned integer value with the range of 0 to 4.29E9 µAh (which will not roll over when full). Does that mean that you can only measure a period that consumes less then 4.29uAh at the time, then stop gauging , read the accumulatedCapacity() , calculate the remaining capacity and start gauging again?

Also, where is the remaining capacity stored in the DF, or does it need to be calculated after every gauge stop command?

Thank you for the help!

Sincerely,

Jorg

over 5 years ago

0 Onyx Ahiakwo over 5 years ago

TI__Guru* 76230 points

Hi Jorg

Yes, the gauge can't measure more than 4.19E9uAh. So you will either have to scale the current if you need a larger value than that following the isntructions in the app note below:

remaining capacity can be calculated by reading the accumulate capacity and subtracting it from design capacity. You do not need to send the gauge stop command to to read accumulated capacity.

thanks

Onyx

0 Jorg over 5 years ago in reply to Onyx Ahiakwo

Intellectual 285 points

Thank you!

I will have a look at the instructions.

Sincerely,

Jorg

0 Jorg over 5 years ago in reply to Onyx Ahiakwo

Intellectual 285 points

Dear Onyx,

I have one small question about the ACC mode left.
Discharging a battery will decrease the accumulated capacity from its highest value 4.19e9uAh to 0?

Thank you,

Jorg

0 Onyx Ahiakwo over 5 years ago in reply to Jorg

TI__Guru* 76230 points

Hi Jorg

There is just the charge accumulation register which will increment as charge flows out of the battery. The max it could increment to is the 4.19e9uAh

thanks

Onyx

0 Jorg over 5 years ago in reply to Onyx Ahiakwo

Intellectual 285 points

Dear Onyx,

My accumulated capacity register begins at about 4.29e9 and then slowly decreases every time the current flows out the battery.

There are no errors to be found and I'm using the typical application. The change in charge is fairly accurate, but it schould increment?

Greetz,

Jorg

0 Jorg over 5 years ago in reply to Onyx Ahiakwo

Intellectual 285 points

Dear Onyx,

I found the answer:

This means the accumulated charge is decreasing.

Greetz,

Jorg

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BQ35100: Accumulated Capacity