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Original question:

BQ24773: how to detect a good/bad battery

BQ24773: How to identify discharge and charge completed battery

Rahul Surawase48
Expert 2395 points
Part Number: BQ24773

Hello TI

just looking for confirmation my understanding is correct...

At POR the Auto-Wake-Up is enabled.

After the PACK reaches 6V (or 3V) the charger sets charging current to 0 (good battery); if not (after 30min timeout) the Auto-Wake-Up bit is cleared.

So monitoring these 2 registers should be sufficient to assert the status of the charger.

Before asserting the battery is gone/bad/damaged (i.e. never reaches 3-6V), the amount of time needed to reach 3/6V can be estimated based on battery capacity/size.

is there any -even indicative- flowchart on how to set (Step by step) registers in BQ24773?

thanks a lot in advance

  • 0
    TI__Mastermind 25800 points

    Hey Rahul,

    What do you mean by "status of the charger"?

    Your understanding is correct. if the battery voltage is too low, the charge current will be set to 128mA automatically. And if the battery voltage does not rise high enough in 30min, then the Auto Wakeup bit will be cleared. 

    Yes, you can estimate how long it will take the battery to reach 3V (1S) or 6V (2S and above) based on the capacity and the 128mA auto wakeup current. Keep in mind that the this would be the worst case time, but in reality if you attach a partially charged battery, time will likely be lower. 

    And what do you mean by flow chart to set the registers? The registers are largely based on what parameters you need or wish to set. If you are looking for a flow chart on the inter-dependencies between registers, we do not. I will say, however, that indirectly section 8.6.6 Setting the Charge Current identifies the important factors that will reset the charging current register, which is typically the most critical in a charger. 

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Expert 2395 points

    Hello Joel, 

    I am looking for to disconnect battery automatically when battery is not able to provide sufficient power to load when the system is operated on battery power

    I am using 5000mAh lithium battery to power the system load (Raspberry PI), we observe the that when Raspberry is power on by using battery it's work continuously  upto 5Hr's but after that start rebooting continuously  which is not acceptable, there is any way to disconnect the load when source is not capable to power 

    Thanks, 

    Rahul Surawase

  • 0 in reply to Rahul Surawase48
    TI__Mastermind 25800 points

    Hey Rahul,

    There is no way to disconnect the battery from the system rail unless you have a add a separate load switch between the charger's system output and your actual system load. 

    Because this charger uses a P-CH. MOSFET as the BATFET, the body effect always allows current to flow from the battery to the system. 

    You could potentially utilize the integrated independent comparator to monitor the battery voltage in order to toggle this switch.

    Regards,

    Joel H