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Gas Gauge needed

Alfredo Grajales
Prodigy 10 points
Other Parts Discussed in Thread: BQ24070, BQ27510EVM, BQ27510-G2

I´m using a bq24070 to charge a li-ion batt in a portable app as a college project. I use solar cells to provide energy to the system and the batt. I read a little about  battery gas gauge ICs to monitor the battery. but I really don´t know how to include that technology in may project. Please anyone point me in the right direction. 

  • 0
    TI__Genius 14985 points

    Hi Alfredo,

    Including a gas gauge function in your project means that you could accurately know the remaining capacity (in mAh), state of charge (SOC in %), run-time, and many other details about your battery condition.  Some "smart" batteries such as those in your laptop computer have a gas gauge IC inside them.  We call this a pack-side gauge.  However, there are many "dumb" batteries out there like a simple cell-phone battery.  To accurately gauge them you will need a system-side gauge.  For single-cell applications you could consider the bq27510-G2.  You could order a bq27510EVM, upgrade the firmware to the latest version (currently G2 is v1.23), and use it to prepare a golden dataflash file to match your battery and system requirements.

    Note that adding this feature is not as simple as just adding the gas gauge IC.  You will need to match your battery profile to an existing one in the TI database, configure the gauge dataflash to match your system requirements, and perform a learning cycle on one battery sample so the gauge can optimize the capacity and resistance values stored in the dataflash.

    To take advantage of the gauge's features you will also need something to read the information from the gauge and take some action.  That could be as simple as a microcontroller like an MSP430 that reads the SOC and lights up some LEDs corresponding to the charge level, or it could display it on an LCD, or just give a warning or shut down your system when the level gets low.

    For help getting started with the EVM, there are a lot of app notes in the product folder on ti.com, but we also recently put some videos online that should help:

    Part 1: Setting up the bq275xx EVM - Battery gauge...

    Part 2: Using the bq275XX EVM software - Battery...

    Part 3: Optimizing the bq275xx EVM with bqEASY...

    If you choose to add this feature to your project, please be sure to budget the extra time to configure it properly.  First time users of gauges are sometimes surprised that the learning process can take longer than they expected.  We are working on more tools to help automate the configuration for you, but for now the videos give a good idea of the process you'll need to follow.

    Best wishes on your project, and do let us know how we can help.  Even if everything goes swimmingly, let the community know how it turns out, if you don't mind!

    Best regards,

    David

    P.S.

    I found this old article from the Analog Applications Journal that might help orient you.  Other interesting topics are also at www.ti.com/aaj

    "Host-side gas-gauge-system design considerations for single-cell handheld applications"     

    http://focus.ti.com/lit/an/slyt285/slyt285.pdf