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Suggest IC for monitoring a 12v Lipo battery. I want to monitor Volts, amps with my arduino using I2c. For my robot

John Dolecki98
Prodigy 60 points
Other Parts Discussed in Thread: BQ76920, BQ4050

I want to design and build a battery monitor to measure volts and amps. I read several of the data sheets but I'm still confused. Being a beginner can anyone suggest whic chip to start with? I want to use the I2c interface to read the data with my arduino.

Thanks, john

  • 0
    TI__Guru 54715 points
    Hi John,
    With a 12V battery you likey have 3 or 4 series cells. For simple measurement the bq76920 monitor will allow measurement of the voltage, temperature and current from the battery, all as digital data over I2C. It supports 3-5 cells, and includes some protection features and balancing capability. The current measurement is with a coulomb counter which intergrates current over a 250ms window, so you do not get peak or instantaneous current. The bq76920 will control low side protection FETs, but check how you are interfacing to the remainder of your system to see if switching the ground is OK or if you need high side protection switching. With a monitor part your arduino will need to provide the battery control and determine what to do with the data, with the voltage and current data you can estimate your battery condition. If you do need instant current you may consider a separate current measurement system or a part with analog output and do a conversion.
    If you want to do less processing there are a number of gauges which support 3 or 4 cells, you might look at the bq4050 as a start. The gauges will typically have measuring, balancing and protection built in and can give you state of charge and run time data. Interface is typically SMBus which is a little different than I2C. The gauge forum will have better knowledge if you go that direction.
    Since you are new to batteries you might find the resources at www.ti.com/.../battery-management-bms-university.page helpful, or other information starting at the www.ti.com/battery page.