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BQ2000: Re: Ni-MH Battery charging Characteristic according our Charging Application

denish limbachiya
Prodigy 30 points
Part Number: BQ2000


Hello sir,

We are evaluating BQ2000 Ni-MH charging IC in our product.

For this product we are facing battery charging Issue during charge battery multiple attempts at our end customer side kindly note in this anlisys report we do charging using diode only not implemanteage any charging IC.

After failure this approach we implement BQ200 NI-MH charging ic

We require your fruitful help to understand of issue and get it's issue.  

For more batter way to understand issue and our schematic we attached ref. document . please review those document 

So in our design we will not facing this type of issue or not?

Kindly not for this product our annual quantity is 10K unit and MOQ is 1k to 2K units.

Waiting for your inputs regarding schematic review and our issue resolution review and confirmation.

Thanks & Regards,

Denish Limbachiya

Sr. EDE Er. 
Teksun Microsys Pvt. ltd.

BQ2000NS NI-MH Charger_Testing step and Issue DESCRIPTION_BQ2000NA Charging IC.docx

  • 0
    TI__Mastermind 41475 points

    Hello,

    I see that you do not have a thermistor attached. You say your battery temperature is increasing, but you do not have any temperature monitoring via a thermistor. Your TS network is fixed. Please program a thermistor if you want temperature control of the battery.

    Also, can you collect a waveform of the input voltage, the output voltage, the output current, and the MOD pin when this is happening?

    Thanks,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 30 points

    Hello Michel,

    Thanks for your inputs.

    as i discuss previous for this IC (BQ2000) we are in design phase but want to know that TI charging IC able to detect full charge detection of NI-MH battery and able to cut off charge process of battery if i attached full charge battery with charging IC and  user apply muliple charging process through charger?

    I did not want to our full charge battery again arrive in charging phase for 15 minute for first over load , then again charging process start then not want to battery goes in charging phase for 30 minute and so on...


    once we arrive in testing phase i will share input , output voltage , and charging current waveform with you.

    Yes right we will implement 10K thermistor with TS Pin instead of resistor network at TS pin.It will be work  for temperature 

    Thanks & Regards,

    Denish Limbachiya

  • 0 in reply to denish limbachiya
    TI__Mastermind 41475 points

    Hello,

    The BQ2000 will terminate based on Peak Voltage Detection, Maximum Temperature, or Maximum Charge Time for NiMH. Please refer to the state diagram in Figure 2. "Following fast charge, the battery is topped off, if top-off is selected. The charging cycle ends with a trickle maintenance-charge that continues as long as the voltage on the BAT pin remains below VMCV."

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answers your question.

  • 0 in reply to Michael Emanuel35
    Prodigy 30 points

    Hello Sir,

    I test circuit as per your suggestion. 

    But at current charging status LED is continues blink even i battery not attached. without battery LED pin should be in high state.

    Then in which condition LED is blink because due to 1Hz LED blink my NI-MH battery is not charged .

    So kindly help for to start battery and LED should be continue low state during battery is connected with charger.

  • 0 in reply to denish limbachiya
    TI__Mastermind 41475 points

    Hello,

    Can you please describe your exact steps that lead the LED pin to blink at 1 Hz?

    Thanks,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 30 points

    Hello Michael,

    Thanks for inputs.

    Kindly find below steps for testing LED blink issue and charging suspend.

    We are using 1.2V NI-MH 2 cell s in series. total voltage of cell is 2.5V @ 1600mAh capacity.

    We charge it through 5V @ 1A output current charger for battery charging.

    Testing step:

    Step 1: first we disconnect battery attached only charger with charging IC we got 4.5V at output side and charging status LED is start to blink as per it's characteristic.

    Step 2 : Attached 2.5V NI-MH charged  battery still this LED start blink

    What is reason for that charging IC not able to detect battery? or anything else? 

    When i attached scope at inductor output side then i can able to see only charging pulse which are tacking 6 mA current for 1 second and another 1 second it is of and same as continues for create charging trickle pulse at battery.

    Can you explain in which case i can see fast charging mode and LED continues glow in red color?

    i want to understand charging process of Ni-Mh battery and working charging range of 1.2V Ni-MH charging battery.

    Thanks,

    Denish Limbachiya

  • 0 in reply to denish limbachiya
    TI__Mastermind 41475 points

    Dear Denish,

    A 1 HZ flash on the LED pin happens in charge qualification. This can happen for two reasons.

    First, the BAT pin is below VLBAT. Can you confirm the voltage of the inserted battery?

    Second, if the TS pin voltage is above VLTF during fast charge. What is your TS voltage?

    Also, you say you are using 2 1.2 V cells in series, for a total of 2.5 V. However, you have set your output to 4 V. What is your intended full charge voltage?

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answers your question.

  • 0 in reply to Michael Emanuel35
    Prodigy 30 points

    Hello Sir,

    Yes right we tune TS pin voltage between  0.9V to 2V and it is resolve our issue.

    Thanks for support,

    It is really appreciate for you and TI team.

    Thanks,

    Denish Limbachiya.