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BQ24650 for Lead acid battery

simone frasanni
Intellectual 285 points
Other Parts Discussed in Thread: BQ24650

Hi to all,

can I use BQ24650 to charge correctly Lead Acid Battery ? I must do a battery charger for solar application and I can utilize both LiFePo4 battery and Lead Acid Battery. For LiFePo4 battery I think it's correct to stop the charge current when the battery is charged. For Lead Acid battery I believe it's important to guarantee a minimum current of keeping for a correct charge.  BQ24650 stops the charge current in any chemistries.

Is LiFePo4 batteries a good choise for high temperature application ? Can I charge it with +60 degree ? Has Li-Ion got better performance for high temperature charging ?

Thanks for the advices.

Regards

Simone

  • 0
    TI__Expert 8690 points

    Hi Simone,

    You can look at the application note www.ti.com/.../slva437a.pdf which explains how to use the bq24650 to charge a lead acid battery. Lead acid capacity diminishes as you increase temperature, usually cuts in half for every 8C of rise in temperature from 25C.

    LiFePO4 can handle more temperature, I've read it can reach up to 70C, but it depends on which one you choose, and is the more safer approach. Look at this app note www.ti.com/.../slua565.pdf .

    Li-ion should not be charged above temperature of  60C, with 45C being the recommended standard to stop charging.

    Regards,
    Steven

  • 0 in reply to Steven Bangdiwala
    Intellectual 285 points

    Hi Steven

    thanks for your cooperation.

    About bq64250 I have an other question : if I have two differents Solar panel, one fixed in a side of the box, and the other fixed in the opposite side (I know it's a bad solution, but the customer imposes this !), How can I connect the two panel to bq24650 ?

    How does MPPSET work in this situation ? If I have irradiation in one panel it's possibile I didn't have in the opposite.

    Can I connect both panels without diode ?

    Thanks in advance

    Regards

    Simone

  • 0 in reply to simone frasanni
    TI__Expert 8690 points
    Simone,

    You should try to separate both through a Diode OR. Connecting two panels with different voltage is bad, as there could be reverse current going into the panel with less voltage and could overheat, eventually damaging the cells. A panel that has poor lighting can get reverse biased, which leads to the reverse current. Unless your panels have shunt diodes to prevent reverse current, I advise that you connect a diode after each panel to prevent the reverse current.

    I have a few questions: What is the end application of the system? What is the battery configuration? If you have information on volume, please provide as well.

    Regards,
    Steven
  • 0 in reply to Steven Bangdiwala
    Intellectual 420 points

    Hiii,

         We are getting problem  in status LED's ,Both LED'S are always ON. we draw a  schematic as you mentioned in  bq24650 datasheet ,How can i overcome it.Please suggest me where i did mistake.

  • 0 in reply to naga reddy
    TI__Expert 8690 points
    Hi Naga,

    Could you share your schematic here? I want to see if there is anything out of place, because the bq24650 itself doesn't have a state where both STAT1 and STAT2 are ON.

    Regards,
    Steven
  • 0 in reply to Steven Bangdiwala
    Intellectual 420 points
    Hii,
    can i reduce the MPPSET value 17.8V to 16V?
    If i changed to 16V what happend?
  • 0 in reply to naga reddy
    TI__Genius 14500 points
    Hi Naga,

    The MPPTSET is set by the solar panel. If the solar panel's maximum power voltage(VMPP) is in 16V, MPPSET could be set on 16V. If VMPP is not on the 16V, it won't get the maximum power from solar panel. Please check if the solar panel you used VMPP is 16V.

    Thanks,
    Ann Lien