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bq24610EVKit Questions

Charles Pakbaz
Prodigy 50 points
Other Parts Discussed in Thread: BQ24610

I'm trying to use the bq24610evkit to charge a 12v lead acid 130AH battery.

As recommended by TI, I added a 10k resistor to TS-GND and i got 12.1v on the V.BAT (with changing R25=490k)

here are my questions:

1. If I'm using a 12V battery, is selection of R25 correct?

1. The battery didn't get fully charged to 12v after 2 days of non-stop charging. the last voltage was read as 10.45v on the battery. this is a new 12v, 130ah Trojan battery which has been discharged only one time. What would be the reason? I'm also using a 19.9V, 10A DC Power Supply as my input to the charger.

2. My AC Power supply is 19.9v, so I get the same voltage on the Load. is there anyway I can reduce the voltage on the Load to 12v as well like the vBat which was done by changing R25?

3. When charger is connected to Electricity, my goal is to be able to charge the battery and in the same time use the AC Power Supply to run my Electronic Device which is connected to the battery. Since the power input of this Device is connected to the battery, by connecting it to the load, I will get a constant voltage to the battery being charged as well. is there any work around for this? (Basically I want to run the device with AC Power when available but have the Battery getting charged in the same time like laptops that are connected to power supplies)   

thanks for your help and support,

Charles

  • 0
    TI__Guru 56650 points

    Question 1. If I'm using a 12V battery, is selection of R25 correct?

    Change R25 can change the VBAT output set point. For example, R25=490k, the VBAT set point is 2.1x (490+100)/100=12.39V. But, what charging voltage is good for that 12V lead acid battery? Please read the battery datasheet and set to a good value.

    bq24610 has a safety timer and pre-charge condition. If the battery voltage is too low in the beginning, the charge only put pre-charge current to battery. Also, if the battery voltage is still lower than VLOW in half hour, the safety time will shut down the charging. Also, if the battery voltage is still lower than VLOW in half hour, but, the battery voltage doesn't reach the set point in the setting time of fast charger safety timer, the safety time will shut down the charging. Please check the charging current and TTC pin setting (Low: disable fast charge safety timer and termination; High: disable fast charge safety timer only).

    2. bq24610 can not regulate the system output voltage.

    3.  I don't quite understand this question. You are saying "Basically I want to run the device with AC Power when available but have the Battery getting charged in the same time like laptops that are connected to power supplies". The bq24610 can run the device with AC Power when available. Are you worry about the battery getting charging current from input, so, input can not power up the device at the same time?  The bq24610 has DPM function. It can handle that condition.

  • 0 in reply to Wang5577
    Prodigy 50 points

    Thank you for the information.

    So I changed R25 to 604k to get 14.7v as the 12v Lead Acid Battery instructions recommend. 

    I also changed the TTC jumper to LOW to disable fast charge timer and termination, but after starting the kit, the STAT1 went off after 30 minutes. I changed the TTC to HI and also w/o jumper and it still terminates charging (STAT1 off) after 30 minutes. Is there any way to keep the charging ON until the battery gets fully charged?

    thanks,

    Charles

  • 0 in reply to Charles Pakbaz
    TI__Guru 56650 points

    Please check the battery voltage (or VFB voltage), if it is lower than Vlowv threshold, the half hour pre-charger timer can turn off the charging. And the pre-charge timer can not be disable.

    The solution is increase pre-charge current (ISET2 voltage). So, the pre-charge current can bring the battery voltage higher than Vlowv threshold in half hour.

  • 0 in reply to Wang5577
    Prodigy 50 points

    Thank you very much for your help Wang. 

    The current Battery voltage is 10.6v. 

    how can I increase the pre-charge current (ISET2 Voltage) and what is the correct value for my case? (I have a 12v lead acid battery and Vbat is set to 14.7v)

     

    thanks again,

    Charles 

  • 0 in reply to Charles Pakbaz
    TI__Guru 56650 points

    Changing R25 to 604kohm can set 14.7Vreg. Changing R15 to 6.49k can set Iset2 to 2V.