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Best programmable gas gauge (for my application)

Chintan Pathak4
Intellectual 845 points
Other Parts Discussed in Thread: BQ78Z100, BQ40Z50, BQ40Z60

I have been wandering about the TI website, and youtube video channel, trying to wrap my head around battery management concepts, and I have come so far. 

We need a battery fuel gauge evaluation module, that should be programmable. I have been through the charger selection tool, and narrowed down a few products. I just some community feedback and validation of my choice here.

What we need it to do is : 

1.  Charge a single-cell Li-Ion battery. 

2.  Measure the charging-discharging current

3.  Measure the charging-discharging voltage. 

4.  Allow programmatic control of all settable parameters. 

5.  Maybe also measure temperature. 

Requirement 4 is mentioned as some of the user's guide that I read, didnt detail the I2C interface and I am confused whether they can be used without the EV2300/2400 adapters, as I wont need them, since I would be updating the parameters through my code and not the Battery management studio. 

Now, to the winning contenders, (and this is not a complete list):

1.  BQ78Z100 : This appears at the top of the list, and seems most advanced. Just not sure, if it fulfills requirement 4 stated above. 

2.  BQ-27742-G1: This does say in the description that  it is programmable. 

3.  BQ27GDK000EVM : This is by-far the funkiest looking and most confusing of the options. It looks power-packed, but I am not sure, if it is programmable and will work for us. 

So, to summarise, we need a battery fuel gauge eval board, that we can program, to periodically set charging voltage etc. and that in turn gives us the battery voltage and current etc. with high-accuracy. Additional features are welcome. Most advanced boards are preferred. 

- Thanks and regards, 

Chintan Pathak, 

Research Scholar, 

University of Washington. 

  • 0
    TI__Guru* 76230 points
    Chintan
    The bq78z100 and the bq27742 as well as the bq40z50 are your best bets.

    Differences:
    78z100 supports 1s and 2s cell configuration, is programmable, works via i2c or hdq interface and has protector functionality for safety.
    bq27742 supports only 1s configuration, is programmable, works via i2c or hdq interface as well and has protector functionality for safety.
    bq40z50 supports 1s, 2s, 3s and 4s cell configuration, is programmable, works via smbus interface and has protector functionality for safety. Most robust and advanced gauge and protector solution.

    there is the bq40z60 which is a charger and gauge in one solution.it supports 1s, 2s, 3s and 4s cell configuration, is programmable, works via smbus interface and has protector functionality for safety. Most robust and advanced charger, gauge and protector solution.

    The GDK is just a tool that helps in evaluating our single cell gauges . It isn't a gauge.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Intellectual 845 points

    Hey Onyx,

    You have been the most helpful for such an out of the world request. If I could trouble you a little more.

     I am guessing, since I need a "A single device to both act as a charger, and gauge"  --- the BQ40z60, is the solution I am looking for.

    I read the introduction in the datasheet, and everything looks great, except  - Fully Integrated 2-Series to 4-Series Cell Li-Ion or Li-Polymer Battery Management Unit , which might be a slight problem when I want to use a single battery. You mentioned about 1s cell configuration in your reply, but I dont see it anywhere in the description. Could you just confirm this fact ? If this doesnt support 1s, then which model is the next best ?

    Also, this unit has 16-bit ADC for gauging. Is this enough accuracy ? Is there a model with a better ADC ? 

    And finally, just to be crystal clear - BQ40z60 can be programmed if I connect the I2C SDA, SCL pins of my host to the SMBD and SMBC pins of the gauge respectively. This way I wont need the adapter or Battery management studio to control it.

     

  • 0 in reply to Chintan Pathak4
    TI__Guru* 76230 points
    i apologizse for that error. bq40z60 supports only 2s to 4s. You can use either of the other devices i listed and any single cell charger from our portfolio. Your host will have the ability to read or write to the registers of the charger to control charging as needed.

    The 16 but ADC for gauging is more than enough. We have two ADCs. One that handles voltage and temperature and the other that handles coulomb counting for current. They are delta sigma ADCs. resolution of the current measurment is 1mA and voltage is 1mV which is more than enough for most customer applications. We don't have any other gauges with a better ADC.

    thanks
    Onyx