BQ35100EVM-795: AccumulatorCap() decreasing in value?

craig

Part Number: BQ35100EVM-795
Other Parts Discussed in Thread: EV2400, BQSTUDIO

Hello,

I current have the bq35100evm in ACC (accumulator mode). The device has been calibrated. I current go through the following cycle:

1)GE is on (jumper is on)
2)check initcomp bit and ensure device is initialized
3)check batterystatus
4)gauge_start
5)read accumulatorcap, voltage, current, and temp
6)gauge_stop
7)read accumulatorcap()
//REPEAT forever.

Anyway the voltage is positive the current flowing is negative. The accumulator cap appears to start near the top value 4.29E^9 and decrease from there.

Reading the documentation it sounds like its supposed to go up in value and not down.

What is it supposed to do?

over 1 year ago

0 Diego over 1 year ago

TI__Mastermind 25490 points

Hi,

Please allow me sometime to look into this.

Thanks,

Evan

0 craig over 1 year ago in reply to Diego

Intellectual 510 points

That would be greatly appreciated-Thanks!

0 Diego over 1 year ago in reply to craig

TI__Mastermind 25490 points

Hi,

Are you using BQstudio + EV2400 to calibrate and communicate with the gauge. I would double check that CC offset, is correct this appear to be the root cause of the direction the gauge counts.

The thread linked below had a similar issue and also links some other relevant threads to your issue.

(+) BQ35100: Accumulated Capacity - BIS - Power management forum - Power management - TI E2E support forums

Regards,

Evan

0 craig over 1 year ago in reply to Diego

Intellectual 510 points

Evan,

Mine consistently goes down, unless the current flowing is zero. Are you certain this is not expected behavior-Have you interfaced with the device yourself? The documentation is suspect, and doesn't specifiy how it works in operation.

0 Diego over 1 year ago in reply to craig

TI__Mastermind 25490 points

Hi,

It should start at 0 and count up. This is what I see on my EVM

Remaining capacity can be calculated by reading the accumulate capacity and subtracting it from design capacity.

Regards,

Evan

0 craig over 1 year ago in reply to Diego

Intellectual 510 points

Even after calibrating with bqstudio, I still get a down count. Maybe its a physical calibration issue?

I currently use the power in place of a battery.

I have the power supply 4.8V connected and load = Open circuit (no current flow),

I calibrate the Voltage in this state.

Then CC offset

Then board offset.

I attache the load (8ohm resistor), Current begins flowing around 438mA.

I calibrate the current in this state.

I then calibrate the temp (Open circuit again, not that I belive it matters).

I still get a negative current and the accumulator down counts.

Can you see an obvious issue in my setup?

I'm using the bq35100evm

Rev B 001

0 Diego over 1 year ago in reply to craig

TI__Mastermind 25490 points

Hi,

Your set up seems ok.

Can you share your .srec file.

Regards,

Evan