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BQ34110: BQ34110 Simplified Schematic for 12v , 17 Ah Lead Acid Battery Monitoring

Bhavik Chaudhari
Prodigy 80 points
Part Number: BQ34110

Hello,

I want to use BQ34110 IC in my application powered with 12v, 17 AH lead acid Battery.

I am referring schematic provided in datasheet. As my application has specified battery voltages & capacity 12v, 17Ah. I want to use fixed resistor divider pair and remove other component which are not required.

I have simplified schematic as attached. Kindly help me to find out these simplifications are valid or not.

Can I use it without MOSFET & Thermistor specified in datasheet.  

Simplified 

  • 0
    TI__Mastermind 42535 points

    Yeah, you can use a fixed divider. However, please keep the thermistor. It is unlikely that the gauge will be right next to the battery, so you need an external thermistor attached to the battery to protect against temperature conditions.

  • 0
    TI__Guru* 81034 points

    Hi Bhavik,

    These modifications should be fine. The FET controlled by VEN is intended to save power - it enables the resistor divider only when a voltage measurement is taken. It will still work without this circuit, but will waste a little power.

    Best regards,

    Matt

  • 0 in reply to Batt
    Prodigy 80 points

    Hello Batt,

    As I referred datasheet, there is internal temperature sensor in BQ34110.

    Can We use internal instead of external thermistor for protection ??

    Thanks

  • 0 in reply to Bhavik Chaudhari
    TI__Mastermind 42535 points

    Hi Bhavik,

    It's not advised but so long as your gauge is placed in contact with the cell it may be used. However, typically we advise an external thermistor on the cell as it will be more accurate and faster in triggering protection than if the gauge were used, if the gauge is not in contact with the cell.

  • 0 in reply to Batt
    Prodigy 80 points

    Hello Batt,

    I have another query regarding charging Lead Acid battery.

    In my application Lead acid battery is charged through Solar. For that I have Solar charger which I can connect to Battery for charging.

    In my application i want to monitor battery using BQ34110 circuit as above i have simplified. Simultaneously I want to charge my lead acid battery.

    For that can I connect solar charger directly  to BAT+ and BAT- ??  or I need any protection circuit ??

    As mentioned in datasheet  Pack-  and BAT- are connected through small pad.

  • 0 in reply to Bhavik Chaudhari
    TI__Mastermind 42535 points

    Hi Bhavik,

    Yes, ideally you would need a protection circuit. When you are connecting the BAT+ and BAT- terminals, you are bypassing the gauge completely. So it's in effect not able to measure passed charge. However, the problem with solar is that charging V is not constant, therefore you may detect false charge termination.

  • 0 in reply to Batt
    Prodigy 80 points

    Hello Batt,

    So if i need to measure charging voltage & current, I have to connect my solar charger output which is constant to BAT+ and PACK- in BQ34110-EVM module.

    Am I right ?? I yes then it can effect to sense resistor or not. Because high current will be passed from solar charger.

  • 0 in reply to Bhavik Chaudhari
    TI__Mastermind 42535 points

    Your charger goes to PACK+ and PACK-. The sense resistor should detect whatever current passes through the current path. So please choose yours appropriately.