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BQ27520 EVM Rev A

Akshay Parnami85
Prodigy 80 points
Other Parts Discussed in Thread: BQ27510, BQSTUDIO

Hi,

I am using a q27520 EVM with EV2300. The problem that I am facing is that the current measured is  negative times the actual current (-1*Actual Current). If I am charging the battery, I am seeing negative current and while discharging, I am seeing a positive current in the software. As per the calibration definition in bqeasy, discharging current is supposed to be negative and charging current should be positive. I have used bq27510 module previously and therefore, I am certain that the definition of bqeasy is correct and therefore the discharging current should be negative. 

eg: if the battery is being charged by 300mA, I am seeing the current as -300mA in the software.

Can somebody tell what is going wrong?

  • 0
    TI__Guru* 76230 points

    Hi Akshay,

    pls use bqstudio instead downloadable from ti.com. Make sure to calibrate the cc and board offsets as well as current. This should fix your problem.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 80 points
    Hi,
    I have tried using bqstudio as well. But, the problem remains the same. I have tested it after calibrating also. Calibration is for offset correction from what I understand. What I observe is that the gain of the equation is being taken as -1*Req_Gain. Right now, I have not even applied any load. I am just charging the battery using power supply where Charger+ is connected to V+ on supply and Charger- on V- supply. I can't test with reversing the connections since my battery has no protection circuit.
    Please let me know if there is any other way to fix this.
    Thanks
    Akshay
  • 0 in reply to Akshay Parnami85
    TI__Guru* 76230 points
    Akshay,
    The problem is that you didn't carry out current calibration correctly. calibrate the current using a positive current . Make sure the current across the sense resistor is going from cell - to pack - (which is indicative of charging) and not the other way around.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 80 points

    Hi Onyx,

    It did solve my problem.

    Thanks!

    Akshay